Add sub stream recording with adaptive quality playback (#24009)

* add sub stream recording with adaptive quality playback

Optionally record a second, lower bitrate stream alongside the main
recording stream via a `record_sub` input role and `record.sub` config block, with its own retention windows.
Recordings rows now carry the stream type plus the media details needed to serve both streams from one manifest: video codec, audio presence, audio codec and rate, and a record-time keyframe index.

Playback resolves coverage across both streams and merges them into a single VOD sequence, falling back to a discontinuity manifest with per-clip init segments when the media signatures differ. The player exposes a quality selector, and an auto governor picks the stream from stall time, bandwidth, codec support, and the save-data hint.

* fix tests and i18n

web/e2e/specs/export.spec.ts

@@ -867,6 +867,31 @@ test.describe("Multi-Camera Export from History @high", () => {
     await frigateApp.page.route("**/api/recordings/unavailable**", (route) =>
       route.fulfill({ json: [] }),
     );
+    // registered after the broad recordings route so it wins the match;
+    // coverage is an object, and the array above crashes the player
+    await frigateApp.page.route("**/api/*/recordings/coverage**", (route) =>
+      route.fulfill({
+        json: {
+          spans: [
+            {
+              start_time: playbackTime - 3600,
+              end_time: playbackTime + 600,
+              streams: ["main"],
+            },
+          ],
+          codecs_compatible: true,
+          streams: {
+            main: {
+              video_codec: "h264",
+              audio_rate: null,
+              audio_codec: null,
+              has_audio: false,
+              bitrate: 2_000_000,
+            },
+          },
+        },
+      }),
+    );
 
     await frigateApp.goto(`/review?timestamp=front_door_${playbackTime}`);
   }

web/public/locales/en/components/player.json

@@ -13,6 +13,20 @@
     "desc": "No frames have been received on the {{cameraName}} <code>detect</code> stream, check error logs"
   },
   "cameraOff": "Camera is off",
+  "quality": {
+    "auto": "Auto",
+    "autoLow": "Playing low quality (limited bandwidth)",
+    "autoLowCodec": "Playing low quality (Original not supported by this browser)",
+    "autoLowSaveData": "Playing low quality (data saver)",
+    "main": "Original",
+    "sub": "Low",
+    "notSupportedBrowser": "Not supported by this browser",
+    "label": "Quality",
+    "noAudio": "No audio",
+    "audioRate": "{{rate}} kHz audio",
+    "audioCodecRate": "{{codec}} {{rate}} kHz",
+    "noRecordings": "No recordings in this time range"
+  },
   "stats": {
     "streamType": {
       "title": "Stream Type:",
@@ -46,7 +60,8 @@
       "submittedFrigatePlus": "Successfully submitted frame to Frigate+"
     },
     "error": {
-      "submitFrigatePlusFailed": "Failed to submit frame to Frigate+"
+      "submitFrigatePlusFailed": "Failed to submit frame to Frigate+",
+      "playRecordingsFailed": "Failed to play recordings (error {{code}}): {{message}}"
     }
   }
 }

web/public/locales/en/config/cameras.json

@@ -196,6 +196,10 @@
       "record": {
         "label": "Record output arguments",
         "description": "Default output arguments for record role streams."
+      },
+      "record_sub": {
+        "label": "Sub stream record output arguments",
+        "description": "Output arguments for record_sub role streams. The record output arguments are used when this is not set."
       }
     },
     "retry_interval": {
@@ -522,6 +526,54 @@
         "description": "Preview quality level (very_low, low, medium, high, very_high)."
       }
     },
+    "sub": {
+      "label": "Sub stream recording",
+      "description": "Settings for recording a second, lower quality stream.",
+      "enabled": {
+        "label": "Enable sub stream recording",
+        "description": "Enable recording of a second, lower quality stream for adaptive quality playback and extended retention."
+      },
+      "continuous": {
+        "label": "Sub stream continuous retention",
+        "description": "Number of days to retain sub stream recordings regardless of tracked objects or motion.",
+        "days": {
+          "label": "Retention days",
+          "description": "Days to retain recordings."
+        }
+      },
+      "motion": {
+        "label": "Sub stream motion retention",
+        "description": "Number of days to retain sub stream recordings triggered by motion.",
+        "days": {
+          "label": "Retention days",
+          "description": "Days to retain recordings."
+        }
+      },
+      "alerts": {
+        "label": "Sub stream alert retention",
+        "description": "Retention settings for sub stream recordings of alerts.",
+        "days": {
+          "label": "Retention days",
+          "description": "Number of days to retain recordings of detection events."
+        },
+        "mode": {
+          "label": "Retention mode",
+          "description": "Mode for retention: all (save all segments), motion (save segments with motion), or active_objects (save segments with active objects)."
+        }
+      },
+      "detections": {
+        "label": "Sub stream detection retention",
+        "description": "Retention settings for sub stream recordings of detections.",
+        "days": {
+          "label": "Retention days",
+          "description": "Number of days to retain recordings of detection events."
+        },
+        "mode": {
+          "label": "Retention mode",
+          "description": "Mode for retention: all (save all segments), motion (save segments with motion), or active_objects (save segments with active objects)."
+        }
+      }
+    },
     "enabled_in_config": {
       "label": "Original recording state",
       "description": "Indicates whether recording was enabled in the original static configuration."

web/public/locales/en/config/global.json

@@ -707,6 +707,10 @@
       "record": {
         "label": "Record output arguments",
         "description": "Default output arguments for record role streams."
+      },
+      "record_sub": {
+        "label": "Sub stream record output arguments",
+        "description": "Output arguments for record_sub role streams. The record output arguments are used when this is not set."
       }
     },
     "retry_interval": {
@@ -1048,6 +1052,54 @@
         "description": "Preview quality level (very_low, low, medium, high, very_high)."
       }
     },
+    "sub": {
+      "label": "Sub stream recording",
+      "description": "Settings for recording a second, lower quality stream.",
+      "enabled": {
+        "label": "Enable sub stream recording",
+        "description": "Enable recording of a second, lower quality stream for adaptive quality playback and extended retention."
+      },
+      "continuous": {
+        "label": "Sub stream continuous retention",
+        "description": "Number of days to retain sub stream recordings regardless of tracked objects or motion.",
+        "days": {
+          "label": "Retention days",
+          "description": "Days to retain recordings."
+        }
+      },
+      "motion": {
+        "label": "Sub stream motion retention",
+        "description": "Number of days to retain sub stream recordings triggered by motion.",
+        "days": {
+          "label": "Retention days",
+          "description": "Days to retain recordings."
+        }
+      },
+      "alerts": {
+        "label": "Sub stream alert retention",
+        "description": "Retention settings for sub stream recordings of alerts.",
+        "days": {
+          "label": "Retention days",
+          "description": "Number of days to retain recordings of detection events."
+        },
+        "mode": {
+          "label": "Retention mode",
+          "description": "Mode for retention: all (save all segments), motion (save segments with motion), or active_objects (save segments with active objects)."
+        }
+      },
+      "detections": {
+        "label": "Sub stream detection retention",
+        "description": "Retention settings for sub stream recordings of detections.",
+        "days": {
+          "label": "Retention days",
+          "description": "Number of days to retain recordings of detection events."
+        },
+        "mode": {
+          "label": "Retention mode",
+          "description": "Mode for retention: all (save all segments), motion (save segments with motion), or active_objects (save segments with active objects)."
+        }
+      }
+    },
     "enabled_in_config": {
       "label": "Original recording state",
       "description": "Indicates whether recording was enabled in the original static configuration."

web/public/locales/en/views/events.json

@@ -21,6 +21,7 @@
   },
   "zoomIn": "Zoom In",
   "zoomOut": "Zoom Out",
+  "subOnlyQuality": "Only low quality recordings are available in this time range",
   "events": {
     "label": "Events",
     "aria": "Select events",

web/public/locales/en/views/settings.json

@@ -398,6 +398,7 @@
         "title": "Stream Roles",
         "detect": "Main feed for object detection.",
         "record": "Saves segments of the video feed based on configuration settings.",
+        "record_sub": "Lower quality recordings for adaptive playback and extended retention (typically the camera sub stream).",
         "audio": "Feed for audio based detection."
       },
       "featuresPopover": {
@@ -1528,6 +1529,7 @@
       "manual": "Manual arguments",
       "inherit": "Inherit from camera setting",
       "none": "None",
+      "sameAsRecord": "Same as record output arguments",
       "useGlobalSetting": "Inherit from global setting",
       "selectPreset": "Select preset",
       "manualPlaceholder": "Enter FFmpeg arguments",
@@ -1648,9 +1650,12 @@
     "inputRoles": {
       "summary": "{{count}} roles selected",
       "empty": "No roles available",
+      "roleInUse": "Already assigned to another stream",
+      "recordSubConflict": "A stream cannot have both record and record_sub roles",
       "options": {
         "detect": "Detect",
         "record": "Record",
+        "record_sub": "Record (Sub Stream)",
         "audio": "Audio"
       }
     },
@@ -1952,7 +1957,8 @@
       "modelSizeLarge": "The 'large' model is optimized for multi-line license plates. The 'small' model provides better performance over 'large' and should be used unless your region uses multi-line plate formats."
     },
     "record": {
-      "noRecordRole": "No streams have the record role defined. Recording will not function."
+      "noRecordRole": "No streams have the record role defined. Recording will not function.",
+      "noRecordSubRole": "No streams have the record_sub role defined. Sub stream recording will not function."
     },
     "birdseye": {
       "objectTrackingDetectDisabled": "Birdseye includes tracked objects, but object detection is disabled for this camera. The camera will not appear in Birdseye."

web/src/components/config-form/section-configs/ffmpeg.ts

@@ -20,6 +20,13 @@ const ffmpegArgsWidget = (
   },
 });
 
+const recordSubArgsWidget = () =>
+  ffmpegArgsWidget("output_args.record_sub", {
+    allowInherit: true,
+    forceSplitLayout: true,
+    unsetLabelKey: "configForm.ffmpegArgs.sameAsRecord",
+  });
+
 const ffmpeg: SectionConfigOverrides = {
   base: {
     sectionDocs: "/configuration/ffmpeg_presets",
@@ -75,6 +82,8 @@ const ffmpeg: SectionConfigOverrides = {
       output_args: "/configuration/ffmpeg_presets#output-args-presets",
       "inputs.output_args": "/configuration/ffmpeg_presets#output-args-presets",
       "output_args.record": "/configuration/ffmpeg_presets#output-args-presets",
+      "output_args.record_sub":
+        "/configuration/ffmpeg_presets#output-args-presets",
       "inputs.roles": "/configuration/cameras/#setting-up-camera-inputs",
       apple_compatibility:
         "/configuration/camera_specific#h265-cameras-via-safari",
@@ -112,9 +121,11 @@ const ffmpeg: SectionConfigOverrides = {
       output_args: {
         detect: arrayAsTextWidget,
         record: ffmpegArgsWidget("output_args.record"),
+        record_sub: recordSubArgsWidget(),
         items: {
           detect: arrayAsTextWidget,
           record: ffmpegArgsWidget("output_args.record"),
+          record_sub: recordSubArgsWidget(),
         },
       },
       inputs: {
@@ -148,6 +159,7 @@ const ffmpeg: SectionConfigOverrides = {
             items: {
               detect: arrayAsTextWidget,
               record: ffmpegArgsWidget("output_args.record"),
+              record_sub: recordSubArgsWidget(),
             },
           },
         },
@@ -176,6 +188,7 @@ const ffmpeg: SectionConfigOverrides = {
       output_args: {
         detect: arrayAsTextWidget,
         record: ffmpegArgsWidget("output_args.record"),
+        record_sub: recordSubArgsWidget(),
       },
     },
   },

web/src/components/config-form/section-configs/record.ts

@@ -15,6 +15,19 @@ const record: SectionConfigOverrides = {
           );
         },
       },
+      {
+        key: "no-record-sub-role",
+        messageKey: "configMessages.record.noRecordSubRole",
+        severity: "warning",
+        condition: (ctx) => {
+          if (ctx.level !== "camera" || !ctx.fullCameraConfig) return false;
+          const sub = ctx.formData?.sub as Record<string, unknown> | undefined;
+          if (!sub?.enabled) return false;
+          return !ctx.fullCameraConfig.ffmpeg?.inputs?.some((i) =>
+            i.roles?.includes("record_sub"),
+          );
+        },
+      },
     ],
     fieldDocs: {
       "alerts.pre_capture":
@@ -34,6 +47,7 @@ const record: SectionConfigOverrides = {
       "motion",
       "alerts",
       "detections",
+      "sub",
       "preview",
       "export",
     ],
@@ -67,6 +81,12 @@ const record: SectionConfigOverrides = {
       "detections.retain.mode": {
         "ui:options": { enumI18nPrefix: "retainMode" },
       },
+      "sub.alerts.mode": {
+        "ui:options": { enumI18nPrefix: "retainMode" },
+      },
+      "sub.detections.mode": {
+        "ui:options": { enumI18nPrefix: "retainMode" },
+      },
       preview: {
         "ui:options": { defaultOpen: true, disableCollapsible: true },
         quality: {

web/src/components/config-form/theme/fields/CameraInputsField.tsx

@@ -193,6 +193,25 @@ export function CameraInputsField(props: FieldProps) {
     }
   }, [fieldPathId.path, inputs, onChange]);
 
+  const getRolesUsedByOtherInputs = useCallback(
+    (index: number): string[] => {
+      const used = new Set<string>();
+      inputs.forEach((input, currentIndex) => {
+        if (currentIndex === index || !Array.isArray(input.roles)) {
+          return;
+        }
+
+        input.roles.forEach((role) => {
+          if (typeof role === "string") {
+            used.add(role);
+          }
+        });
+      });
+      return [...used];
+    },
+    [inputs],
+  );
+
   const handleFieldValueChange = useCallback(
     (index: number, fieldName: string, nextValue: unknown) => {
       const nextInputs = cloneDeep(inputs);
@@ -466,7 +485,16 @@ export function CameraInputsField(props: FieldProps) {
                     />
                   </div>
 
-                  <div className="w-full">{renderField(index, "roles")}</div>
+                  <div className="w-full">
+                    {renderField(index, "roles", {
+                      extraUiSchema: {
+                        "ui:options": {
+                          rolesUsedByOtherInputs:
+                            getRolesUsedByOtherInputs(index),
+                        },
+                      },
+                    })}
+                  </div>
 
                   {renderField(index, "input_args")}
 

web/src/components/config-form/theme/widgets/FfmpegArgsWidget.tsx

@@ -30,6 +30,7 @@ type PresetField =
   | "hwaccel_args"
   | "input_args"
   | "output_args.record"
+  | "output_args.record_sub"
   | "output_args.detect";
 
 const getPresetOptions = (
@@ -49,7 +50,10 @@ const getPresetOptions = (
   }
 
   if (field.startsWith("output_args.")) {
-    const key = field.split(".")[1] as "record" | "detect";
+    const key =
+      field === "output_args.record_sub"
+        ? "record"
+        : (field.split(".")[1] as "record" | "detect");
     return data.output_args?.[key] ?? [];
   }
 
@@ -127,6 +131,7 @@ export function FfmpegArgsWidget(props: WidgetProps) {
   const globalFieldPath =
     (options?.ffmpegGlobalFieldPath as string | undefined) ?? presetField;
   const allowInherit = options?.allowInherit === true;
+  const unsetLabelKey = options?.unsetLabelKey as string | undefined;
   const hideDescription = options?.hideDescription === true;
   const useSplitLayout = options?.splitLayout !== false;
 
@@ -287,6 +292,12 @@ export function FfmpegArgsWidget(props: WidgetProps) {
         : "ffmpeg.output_args.record.description";
     }
 
+    if (presetField === "output_args.record_sub") {
+      return isInputScoped
+        ? "ffmpeg.inputs.output_args.record_sub.description"
+        : "ffmpeg.output_args.record_sub.description";
+    }
+
     if (presetField === "output_args.detect") {
       return isInputScoped
         ? "ffmpeg.inputs.output_args.detect.description"
@@ -345,7 +356,9 @@ export function FfmpegArgsWidget(props: WidgetProps) {
               }
             />
             <label htmlFor={`${id}-inherit`} className="cursor-pointer text-sm">
-              {t("configForm.ffmpegArgs.inherit", { ns: "views/settings" })}
+              {t(unsetLabelKey ?? "configForm.ffmpegArgs.inherit", {
+                ns: "views/settings",
+              })}
             </label>
           </div>
         ) : (
@@ -361,7 +374,9 @@ export function FfmpegArgsWidget(props: WidgetProps) {
               }
             />
             <label htmlFor={`${id}-none`} className="cursor-pointer text-sm">
-              {t("configForm.ffmpegArgs.none", { ns: "views/settings" })}
+              {t(unsetLabelKey ?? "configForm.ffmpegArgs.none", {
+                ns: "views/settings",
+              })}
             </label>
           </div>
         )}

web/src/components/config-form/theme/widgets/InputRolesWidget.tsx

@@ -3,7 +3,14 @@ import { useMemo } from "react";
 import { useTranslation } from "react-i18next";
 import { Switch } from "@/components/ui/switch";
 
-const INPUT_ROLES = ["detect", "record", "audio"] as const;
+const INPUT_ROLES = ["detect", "record", "record_sub", "audio"] as const;
+
+// Recording the sub stream from the same input as record would just
+// re-record the main stream, so the two roles are mutually exclusive.
+const CONFLICTING_ROLES: Partial<Record<string, string>> = {
+  record: "record_sub",
+  record_sub: "record",
+};
 
 function normalizeValue(value: unknown): string[] {
   if (Array.isArray(value)) {
@@ -18,11 +25,18 @@ function normalizeValue(value: unknown): string[] {
 }
 
 export function InputRolesWidget(props: WidgetProps) {
-  const { id, value, disabled, readonly, onChange } = props;
+  const { id, value, disabled, readonly, onChange, options } = props;
   const { t } = useTranslation(["views/settings"]);
 
   const selectedRoles = useMemo(() => normalizeValue(value), [value]);
 
+  // Each role may only be assigned to a single input, so roles already
+  // used by sibling inputs are locked.
+  const rolesUsedByOtherInputs = useMemo(
+    () => normalizeValue(options?.rolesUsedByOtherInputs),
+    [options],
+  );
+
   const toggleRole = (role: string, enabled: boolean) => {
     if (enabled) {
       if (!selectedRoles.includes(role)) {
@@ -39,6 +53,20 @@ export function InputRolesWidget(props: WidgetProps) {
       <div className="grid gap-2">
         {INPUT_ROLES.map((role) => {
           const checked = selectedRoles.includes(role);
+          const usedByOtherInput =
+            !checked && rolesUsedByOtherInputs.includes(role);
+          const conflictingRole = CONFLICTING_ROLES[role];
+          const hasConflict =
+            !checked &&
+            conflictingRole !== undefined &&
+            selectedRoles.includes(conflictingRole);
+          const hint = usedByOtherInput
+            ? t("configForm.inputRoles.roleInUse", { ns: "views/settings" })
+            : hasConflict
+              ? t("configForm.inputRoles.recordSubConflict", {
+                  ns: "views/settings",
+                })
+              : undefined;
           const label = t(`configForm.inputRoles.options.${role}`, {
             ns: "views/settings",
             defaultValue: role,
@@ -49,13 +77,20 @@ export function InputRolesWidget(props: WidgetProps) {
               key={role}
               className="flex items-center justify-between rounded-md px-3 py-0"
             >
-              <label htmlFor={`${id}-${role}`} className="text-sm">
-                {label}
-              </label>
+              <div className="flex flex-col">
+                <label htmlFor={`${id}-${role}`} className="text-sm">
+                  {label}
+                </label>
+                {hint ? (
+                  <span className="text-xs text-muted-foreground">{hint}</span>
+                ) : null}
+              </div>
               <Switch
                 id={`${id}-${role}`}
                 checked={checked}
-                disabled={disabled || readonly}
+                disabled={
+                  disabled || readonly || usedByOtherInput || hasConflict
+                }
                 onCheckedChange={(enabled) => toggleRole(role, !!enabled)}
               />
             </div>

web/src/components/filter/ReviewFilterGroup.tsx

@@ -14,12 +14,10 @@ import { FaCheckCircle, FaFilter, FaRunning } from "react-icons/fa";
 import { isDesktop, isMobile } from "react-device-detect";
 import { Switch } from "../ui/switch";
 import { Label } from "../ui/label";
-import MobileReviewSettingsDrawer, {
-  DrawerFeatures,
-} from "../overlay/MobileReviewSettingsDrawer";
+import MobileReviewSettingsDrawer from "../overlay/MobileReviewSettingsDrawer";
 import useOptimisticState from "@/hooks/use-optimistic-state";
 import FilterSwitch from "./FilterSwitch";
-import { FilterList, GeneralFilter } from "@/types/filter";
+import { DrawerFeatures, FilterList, GeneralFilter } from "@/types/filter";
 import CalendarFilterButton from "./CalendarFilterButton";
 import { CamerasFilterButton } from "./CamerasFilterButton";
 import PlatformAwareDialog from "../overlay/dialog/PlatformAwareDialog";

web/src/components/overlay/MobileReviewSettingsDrawer.tsx

@@ -10,7 +10,12 @@ import {
   DebugReplayContent,
   SaveDebugReplayOverlay,
 } from "./DebugReplayDialog";
-import { ExportMode, GeneralFilter } from "@/types/filter";
+import {
+  DEFAULT_DRAWER_FEATURES,
+  DrawerFeatures,
+  ExportMode,
+  GeneralFilter,
+} from "@/types/filter";
 import ReviewActivityCalendar from "./ReviewActivityCalendar";
 import { SelectSeparator } from "../ui/select";
 import {
@@ -31,6 +36,14 @@ import { StartExportResponse } from "@/types/export";
 import { ShareTimestampContent } from "./ShareTimestampDialog";
 import { useIsAdmin } from "@/hooks/use-is-admin";
 import { cn } from "@/lib/utils";
+import { FaTriangleExclamation } from "react-icons/fa6";
+import { MdHighQuality } from "react-icons/md";
+import { QualitySelectorContent } from "../player/QualitySelector";
+import {
+  AutoQualityReason,
+  PlaybackQuality,
+  RecordingCoverage,
+} from "@/types/record";
 
 type DrawerMode =
   | "none"
@@ -39,25 +52,8 @@ type DrawerMode =
   | "calendar"
   | "filter"
   | "debug-replay"
-  | "share-timestamp";
-
-const DRAWER_FEATURES = [
-  "export",
-  "calendar",
-  "filter",
-  "debug-replay",
-  "share-timestamp",
-  "motion-search",
-] as const;
-export type DrawerFeatures = (typeof DRAWER_FEATURES)[number];
-const DEFAULT_DRAWER_FEATURES: DrawerFeatures[] = [
-  "export",
-  "calendar",
-  "filter",
-  "debug-replay",
-  "share-timestamp",
-  "motion-search",
-];
+  | "share-timestamp"
+  | "quality";
 
 type MobileReviewSettingsDrawerProps = {
   features?: DrawerFeatures[];
@@ -84,6 +80,12 @@ type MobileReviewSettingsDrawerProps = {
   setRange: (range: TimeRange | undefined) => void;
   setMode: (mode: ExportMode) => void;
   setShowExportPreview: (showPreview: boolean) => void;
+  quality?: PlaybackQuality;
+  onSetQuality?: (quality: PlaybackQuality) => void;
+  qualityStreams?: RecordingCoverage["streams"];
+  qualityAutoLow?: boolean;
+  qualityAutoLowReason?: AutoQualityReason;
+  qualityMainUnsupported?: boolean;
 };
 export default function MobileReviewSettingsDrawer({
   features = DEFAULT_DRAWER_FEATURES,
@@ -110,12 +112,19 @@ export default function MobileReviewSettingsDrawer({
   setRange,
   setMode,
   setShowExportPreview,
+  quality,
+  onSetQuality,
+  qualityStreams,
+  qualityAutoLow,
+  qualityAutoLowReason,
+  qualityMainUnsupported,
 }: MobileReviewSettingsDrawerProps) {
   const { t } = useTranslation([
     "views/recording",
     "components/dialog",
     "views/replay",
     "views/events",
+    "components/player",
     "common",
   ]);
   const isAdmin = useIsAdmin();
@@ -395,6 +404,21 @@ export default function MobileReviewSettingsDrawer({
             {t("filter")}
           </Button>
         )}
+        {features.includes("quality") && onSetQuality && (
+          <Button
+            className="flex w-full items-center justify-center gap-2"
+            aria-label={t("quality.label", { ns: "components/player" })}
+            onClick={() => setDrawerMode("quality")}
+          >
+            <div className="relative">
+              <MdHighQuality className="size-5 rounded-md bg-secondary-foreground fill-secondary p-1" />
+              {qualityAutoLow && (
+                <FaTriangleExclamation className="absolute -bottom-1 -right-1 size-2.5 text-danger" />
+              )}
+            </div>
+            {t("quality.label", { ns: "components/player" })}
+          </Button>
+        )}
         {features.includes("share-timestamp") && (
           <Button
             className="flex w-full items-center justify-center gap-2"
@@ -623,6 +647,33 @@ export default function MobileReviewSettingsDrawer({
         }}
       />
     );
+  } else if (drawerMode == "quality") {
+    content = (
+      <div className="flex w-full flex-col">
+        <div className="relative mb-2 h-8 w-full">
+          <div
+            className="absolute left-0 text-selected"
+            onClick={() => setDrawerMode("select")}
+          >
+            {t("button.back", { ns: "common" })}
+          </div>
+          <div className="absolute left-1/2 -translate-x-1/2 text-muted-foreground">
+            {t("quality.label", { ns: "components/player" })}
+          </div>
+        </div>
+        <QualitySelectorContent
+          quality={quality ?? "auto"}
+          onSetQuality={(newQuality) => {
+            onSetQuality?.(newQuality);
+            setDrawerMode("none");
+          }}
+          streams={qualityStreams}
+          autoLow={qualityAutoLow}
+          autoLowReason={qualityAutoLowReason}
+          mainUnsupported={qualityMainUnsupported}
+        />
+      </div>
+    );
   } else if (drawerMode == "share-timestamp") {
     content = (
       <div className="w-full">

web/src/components/player/HlsVideoPlayer.tsx

@@ -26,7 +26,7 @@ import { useIsAdmin } from "@/hooks/use-is-admin";
 // Android native hls does not seek correctly
 const USE_NATIVE_HLS = false;
 const HLS_MIME_TYPE = "application/vnd.apple.mpegurl" as const;
-const unsupportedErrorCodes = [
+const unsupportedErrorCodes: number[] = [
   MediaError.MEDIA_ERR_SRC_NOT_SUPPORTED,
   MediaError.MEDIA_ERR_DECODE,
 ];
@@ -58,6 +58,14 @@ type HlsVideoPlayerProps = {
   onSnapshot?: (playTime: number) => Promise<void> | void;
   toggleFullscreen?: () => void;
   onError?: (error: RecordingPlayerError) => void;
+  onStallStart?: () => void;
+  onStallEnd?: () => void;
+  onSeekStart?: () => void;
+  onBandwidthSample?: (estimateBps: number, levelBitrateBps?: number) => void;
+  onFatalNetworkError?: () => boolean;
+  onFatalCodecError?: () => boolean;
+  initialBandwidthEstimate?: number;
+  bufferLength?: number;
   isDetailMode?: boolean;
   camera?: string;
   currentTimeOverride?: number;
@@ -86,6 +94,14 @@ export default function HlsVideoPlayer({
   onSnapshot,
   toggleFullscreen,
   onError,
+  onStallStart,
+  onStallEnd,
+  onSeekStart,
+  onBandwidthSample,
+  onFatalNetworkError,
+  onFatalCodecError,
+  initialBandwidthEstimate,
+  bufferLength,
   isDetailMode = false,
   camera,
   currentTimeOverride,
@@ -101,9 +117,37 @@ export default function HlsVideoPlayer({
   // playback
 
   const hlsRef = useRef<Hls>(undefined);
-  const [useHlsCompat, setUseHlsCompat] = useState(false);
+  // kept in a ref so changing callback identities do not recreate the
+  // Hls instance; the setup effect must only re-run on source changes
+  const qualitySignalsRef = useRef({
+    onStallStart,
+    onStallEnd,
+    onSeekStart,
+    onBandwidthSample,
+    onFatalNetworkError,
+    onFatalCodecError,
+    initialBandwidthEstimate,
+  });
+  // must resolve before the first render: a mount-effect flip would run
+  // the first source effect in native mode, briefly handing iOS a native
+  // HLS src that hls.js then tears away mid-load
+  const [useHlsCompat, setUseHlsCompat] = useState(() => {
+    if (
+      USE_NATIVE_HLS &&
+      document.createElement("video").canPlayType(HLS_MIME_TYPE)
+    ) {
+      return false;
+    }
+    return Hls.isSupported();
+  });
   const [loadedMetadata, setLoadedMetadata] = useState(false);
   const [bufferTimeout, setBufferTimeout] = useState<NodeJS.Timeout>();
+  // native HLS playback has no MSE, so it recovers from pipeline errors
+  // by reloading the source; one attempt per source
+  const nativeRetryRef = useRef(0);
+  // a ref rather than an effect-scoped counter so the element error
+  // handler can hold its toast while a recovery is still possible
+  const mediaRecoveryBudgetRef = useRef(0);
 
   const applyVideoDimensions = useCallback(
     (width: number, height: number) => {
@@ -153,27 +197,38 @@ export default function HlsVideoPlayer({
   }, [videoRef, applyVideoDimensions]);
 
   useEffect(() => {
-    if (!videoRef.current) {
-      return;
-    }
-
-    if (USE_NATIVE_HLS && videoRef.current.canPlayType(HLS_MIME_TYPE)) {
-      return;
-    } else if (Hls.isSupported()) {
-      setUseHlsCompat(true);
-    }
-  }, [videoRef]);
+    qualitySignalsRef.current = {
+      onStallStart,
+      onStallEnd,
+      onSeekStart,
+      onBandwidthSample,
+      onFatalNetworkError,
+      onFatalCodecError,
+      initialBandwidthEstimate,
+    };
+  }, [
+    onStallStart,
+    onStallEnd,
+    onSeekStart,
+    onBandwidthSample,
+    onFatalNetworkError,
+    onFatalCodecError,
+    initialBandwidthEstimate,
+  ]);
 
   useEffect(() => {
     if (!videoRef.current) {
       return;
     }
 
-    setLoadedMetadata(false);
-
+    // loadedMetadata is intentionally NOT reset here: on a source swap
+    // the element already holds a decoded frame, and keeping it visible
+    // bridges the gap while the new source loads
     const currentPlaybackRate = videoRef.current.playbackRate;
 
     if (!useHlsCompat) {
+      nativeRetryRef.current = 0;
+      mediaRecoveryBudgetRef.current = 0;
       videoRef.current.src = currentSource.playlist;
       videoRef.current.load();
       return;
@@ -181,14 +236,68 @@ export default function HlsVideoPlayer({
 
     // Base HLS configuration
     const hlsConfig: Partial<HlsConfig> = {
-      maxBufferLength: 10,
+      maxBufferLength: bufferLength ?? 10,
       maxBufferSize: 20 * 1000 * 1000,
       startPosition: currentSource.startPosition,
     };
 
-    hlsRef.current = new Hls(hlsConfig);
-    hlsRef.current.attachMedia(videoRef.current);
-    hlsRef.current.loadSource(currentSource.playlist);
+    // every quality switch and chunk change recreates the instance, so
+    // seed it to keep measured throughput across source swaps
+    const seedEstimate = qualitySignalsRef.current.initialBandwidthEstimate;
+    if (seedEstimate !== undefined && seedEstimate > 0) {
+      hlsConfig.abrEwmaDefaultEstimate = seedEstimate;
+    }
+
+    const hls = new Hls(hlsConfig);
+    hlsRef.current = hls;
+    let networkRecoveryAttempts = 0;
+    mediaRecoveryBudgetRef.current = 1;
+    hls.on(Hls.Events.ERROR, (_event, data) => {
+      if (data.fatal) {
+        if (data.type === Hls.ErrorTypes.NETWORK_ERROR) {
+          // prefer a quality downswitch; fall back to restarting loading
+          const handled =
+            qualitySignalsRef.current.onFatalNetworkError?.() ?? false;
+          if (!handled && networkRecoveryAttempts < 2) {
+            networkRecoveryAttempts += 1;
+            hls.startLoad();
+          }
+        } else if (data.type === Hls.ErrorTypes.MEDIA_ERROR) {
+          // retrying the same codec cannot succeed, so a codec error
+          // prefers a quality downswitch over recovery
+          const isCodecError =
+            data.details ===
+              Hls.ErrorDetails.BUFFER_INCOMPATIBLE_CODECS_ERROR ||
+            data.details === Hls.ErrorDetails.BUFFER_ADD_CODEC_ERROR;
+          if (isCodecError && qualitySignalsRef.current.onFatalCodecError?.()) {
+            return;
+          }
+          if (!isCodecError && mediaRecoveryBudgetRef.current > 0) {
+            mediaRecoveryBudgetRef.current -= 1;
+            hls.recoverMediaError();
+          }
+        }
+        return;
+      }
+
+      // hls.js reports each stall episode only once, so STALL_RESOLVED
+      // below is what closes it
+      if (data.details === Hls.ErrorDetails.BUFFER_STALLED_ERROR) {
+        qualitySignalsRef.current.onStallStart?.();
+      }
+    });
+    hls.on(Hls.Events.STALL_RESOLVED, () => {
+      qualitySignalsRef.current.onStallEnd?.();
+    });
+    hls.on(Hls.Events.FRAG_LOADED, () => {
+      // manifests are single-variant, so the bitrate is always level 0
+      qualitySignalsRef.current.onBandwidthSample?.(
+        hls.bandwidthEstimate,
+        hls.levels?.[0]?.bitrate || undefined,
+      );
+    });
+    hls.attachMedia(videoRef.current);
+    hls.loadSource(currentSource.playlist);
     videoRef.current.playbackRate = currentPlaybackRate;
 
     return () => {
@@ -199,7 +308,7 @@ export default function HlsVideoPlayer({
         hlsRef.current.destroy();
       }
     };
-  }, [videoRef, hlsRef, useHlsCompat, currentSource]);
+  }, [videoRef, hlsRef, useHlsCompat, currentSource, bufferLength]);
 
   // state handling
 
@@ -481,21 +590,38 @@ export default function HlsVideoPlayer({
                 );
               }
             }}
-            onPlaying={onPlaying}
+            onPlaying={() => {
+              qualitySignalsRef.current.onStallEnd?.();
+              onPlaying?.();
+            }}
             onPause={() => {
               setIsPlaying(false);
               clearTimeout(bufferTimeout);
 
+              // paused time must never count as stall time
+              qualitySignalsRef.current.onStallEnd?.();
+
               if (isMobile && mobileCtrlTimeout) {
                 clearTimeout(mobileCtrlTimeout);
               }
             }}
+            onSeeking={() => {
+              // iOS ManagedMediaSource gates hls.js fragment loading off
+              // while paused and never resumes it on seek, so a seek
+              // into unbuffered media would never complete
+              hlsRef.current?.resumeBuffering();
+              qualitySignalsRef.current.onSeekStart?.();
+            }}
             onWaiting={() => {
-              if (onError != undefined) {
-                if (videoRef.current?.paused) {
-                  return;
-                }
+              if (videoRef.current?.paused) {
+                return;
+              }
 
+              // the only stall signal under native HLS playback, which
+              // emits no hls.js events
+              qualitySignalsRef.current.onStallStart?.();
+
+              if (onError != undefined) {
                 setBufferTimeout(
                   setTimeout(() => {
                     if (
@@ -551,23 +677,52 @@ export default function HlsVideoPlayer({
               }
             }}
             onError={(e) => {
-              if (
-                !hlsRef.current &&
-                // @ts-expect-error code does exist
-                unsupportedErrorCodes.includes(e.target.error.code) &&
-                videoRef.current
-              ) {
-                setLoadedMetadata(false);
-                setUseHlsCompat(true);
-              } else {
-                toast.error(
-                  // @ts-expect-error code does exist
-                  `Failed to play recordings (error ${e.target.error.code}): ${e.target.error.message}`,
-                  {
-                    position: "top-center",
-                  },
-                );
+              const mediaError = (e.target as HTMLVideoElement).error;
+
+              if (!mediaError) {
+                return;
               }
+
+              // an intentional source swap aborts the in-flight load;
+              // that abort is not an error the user can act on
+              if (mediaError.code === MediaError.MEDIA_ERR_ABORTED) {
+                return;
+              }
+
+              // hold the toast while the fatal handler still has a retry
+              // left; a failed recovery raises a second element error
+              if (hlsRef.current && mediaRecoveryBudgetRef.current > 0) {
+                return;
+              }
+
+              if (!hlsRef.current && videoRef.current) {
+                if (
+                  unsupportedErrorCodes.includes(mediaError.code) &&
+                  Hls.isSupported()
+                ) {
+                  setLoadedMetadata(false);
+                  setUseHlsCompat(true);
+                  return;
+                }
+
+                // native pipeline errors around source swaps are usually
+                // transient, and hls.js is no fallback without MSE
+                if (nativeRetryRef.current < 1) {
+                  nativeRetryRef.current += 1;
+                  videoRef.current.load();
+                  return;
+                }
+              }
+
+              toast.error(
+                t("toast.error.playRecordingsFailed", {
+                  code: mediaError.code,
+                  message: mediaError.message,
+                }),
+                {
+                  position: "top-center",
+                },
+              );
             }}
           />
         </div>

web/src/components/player/QualitySelector.tsx

@@ -0,0 +1,245 @@
+import { useCallback, useMemo } from "react";
+import { useTranslation } from "react-i18next";
+import { isDesktop } from "react-device-detect";
+import { FaTriangleExclamation } from "react-icons/fa6";
+import { MdHighQuality } from "react-icons/md";
+import { Button } from "@/components/ui/button";
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuRadioGroup,
+  DropdownMenuRadioItem,
+  DropdownMenuTrigger,
+} from "@/components/ui/dropdown-menu";
+import {
+  AutoQualityReason,
+  PLAYBACK_QUALITIES,
+  PlaybackQuality,
+  RecordingCoverage,
+  StreamMediaSummary,
+} from "@/types/record";
+
+const CODEC_DISPLAY_NAMES: Record<string, string> = {
+  h264: "H.264",
+  hevc: "H.265",
+  h265: "H.265",
+  av1: "AV1",
+};
+
+const AUDIO_CODEC_DISPLAY_NAMES: Record<string, string> = {
+  aac: "AAC",
+  pcm_alaw: "PCM-A",
+  pcm_mulaw: "PCM-U",
+  opus: "Opus",
+  mp3: "MP3",
+};
+
+type QualitySubtitleProps = {
+  streams?: RecordingCoverage["streams"];
+  autoLow?: boolean;
+  autoLowReason?: AutoQualityReason;
+  mainUnsupported?: boolean;
+};
+
+type QualitySelectorProps = QualitySubtitleProps & {
+  quality: PlaybackQuality;
+  onSetQuality: (quality: PlaybackQuality) => void;
+  setControlsOpen?: (open: boolean) => void;
+  containerRef?: React.MutableRefObject<HTMLDivElement | null>;
+};
+
+function useQualitySubtitles({
+  streams,
+  autoLow,
+  autoLowReason,
+  mainUnsupported,
+}: QualitySubtitleProps) {
+  const { t } = useTranslation(["components/player"]);
+
+  const streamSubtitle = useCallback(
+    (summary?: StreamMediaSummary) => {
+      if (!summary) {
+        return undefined;
+      }
+
+      const parts: string[] = [];
+
+      if (summary.video_codec != null) {
+        parts.push(
+          CODEC_DISPLAY_NAMES[summary.video_codec] ??
+            summary.video_codec.toUpperCase(),
+        );
+      }
+
+      // the codec decides whether the browser plays sound at all (AAC
+      // decodes, G.711 does not), so lead with it when known
+      const audioCodec =
+        summary.audio_codec != null
+          ? (AUDIO_CODEC_DISPLAY_NAMES[summary.audio_codec] ??
+            summary.audio_codec.toUpperCase())
+          : null;
+
+      if (summary.has_audio === false) {
+        parts.push(t("quality.noAudio"));
+      } else if (audioCodec != null && summary.audio_rate != null) {
+        parts.push(
+          t("quality.audioCodecRate", {
+            codec: audioCodec,
+            rate: summary.audio_rate / 1000,
+          }),
+        );
+      } else if (audioCodec != null) {
+        parts.push(audioCodec);
+      } else if (summary.audio_rate != null) {
+        parts.push(t("quality.audioRate", { rate: summary.audio_rate / 1000 }));
+      }
+
+      return parts.length ? parts.join(" · ") : undefined;
+    },
+    [t],
+  );
+
+  const subtitles = useMemo<Partial<Record<PlaybackQuality, string>>>(
+    () => ({
+      auto: autoLow
+        ? t(
+            autoLowReason === "codec"
+              ? "quality.autoLowCodec"
+              : autoLowReason === "saveData"
+                ? "quality.autoLowSaveData"
+                : "quality.autoLow",
+          )
+        : undefined,
+      // a stream absent from the summary has no footage in this range,
+      // and a pin is never silently substituted
+      main:
+        streams && !streams.main
+          ? t("quality.noRecordings")
+          : mainUnsupported
+            ? t("quality.notSupportedBrowser")
+            : streamSubtitle(streams?.main),
+      sub:
+        streams && !streams.sub
+          ? t("quality.noRecordings")
+          : streamSubtitle(streams?.sub),
+    }),
+    [autoLow, autoLowReason, mainUnsupported, streamSubtitle, streams, t],
+  );
+
+  return subtitles;
+}
+
+export default function QualitySelector({
+  quality,
+  onSetQuality,
+  setControlsOpen,
+  containerRef,
+  streams,
+  autoLow,
+  autoLowReason,
+  mainUnsupported,
+}: QualitySelectorProps) {
+  const { t } = useTranslation(["components/player"]);
+  const subtitles = useQualitySubtitles({
+    streams,
+    autoLow,
+    autoLowReason,
+    mainUnsupported,
+  });
+
+  const itemContent = useCallback(
+    (q: PlaybackQuality) => (
+      <div className="flex flex-col">
+        <span>{t(`quality.${q}`)}</span>
+        {subtitles[q] && (
+          <span className="text-xs text-muted-foreground">{subtitles[q]}</span>
+        )}
+      </div>
+    ),
+    [subtitles, t],
+  );
+
+  const trigger = (
+    <Button
+      className="flex items-center gap-2.5 rounded-lg"
+      aria-label={t("quality.label")}
+      size="sm"
+    >
+      <div className="relative">
+        <MdHighQuality className="size-5 text-secondary-foreground" />
+        {autoLow && (
+          <FaTriangleExclamation className="absolute -bottom-0.5 -right-1 size-3 text-danger" />
+        )}
+      </div>
+      {isDesktop && <div className="text-primary">{t("quality.label")}</div>}
+    </Button>
+  );
+
+  return (
+    <DropdownMenu
+      onOpenChange={(open) => {
+        if (setControlsOpen) {
+          setControlsOpen(open);
+        }
+      }}
+    >
+      <DropdownMenuTrigger asChild>{trigger}</DropdownMenuTrigger>
+      <DropdownMenuContent
+        portalProps={{
+          container: containerRef?.current,
+        }}
+      >
+        <DropdownMenuRadioGroup
+          value={quality}
+          onValueChange={(value) => onSetQuality(value as PlaybackQuality)}
+        >
+          {PLAYBACK_QUALITIES.map((q) => (
+            <DropdownMenuRadioItem key={q} value={q} className="cursor-pointer">
+              {itemContent(q)}
+            </DropdownMenuRadioItem>
+          ))}
+        </DropdownMenuRadioGroup>
+      </DropdownMenuContent>
+    </DropdownMenu>
+  );
+}
+
+type QualitySelectorContentProps = QualitySubtitleProps & {
+  quality: PlaybackQuality;
+  onSetQuality: (quality: PlaybackQuality) => void;
+};
+
+// drawer-friendly variant of the selector for the mobile settings drawer
+export function QualitySelectorContent({
+  quality,
+  onSetQuality,
+  streams,
+  autoLow,
+  autoLowReason,
+  mainUnsupported,
+}: QualitySelectorContentProps) {
+  const { t } = useTranslation(["components/player"]);
+  const subtitles = useQualitySubtitles({
+    streams,
+    autoLow,
+    autoLowReason,
+    mainUnsupported,
+  });
+
+  return (
+    <div className="flex w-full flex-col items-center gap-2">
+      {PLAYBACK_QUALITIES.map((q) => (
+        <div
+          key={q}
+          className={`w-full cursor-pointer rounded-lg py-2 text-center ${quality == q ? "bg-secondary" : ""}`}
+          onClick={() => onSetQuality(q)}
+        >
+          <div className="smart-capitalize">{t(`quality.${q}`)}</div>
+          {subtitles[q] && (
+            <div className="text-xs text-muted-foreground">{subtitles[q]}</div>
+          )}
+        </div>
+      ))}
+    </div>
+  );
+}

web/src/components/player/dynamic/AutoQualityGovernor.ts

@@ -0,0 +1,372 @@
+/**
+ * Policy engine for auto playback quality downswitching.
+ *
+ * Stall time is measured rather than counted: hls.js reports
+ * BUFFER_STALLED_ERROR only once per episode (the flag resets only when
+ * playback resumes), so counting events makes the worst networks, where
+ * one freeze never resolves, the least likely to ever downswitch.
+ */
+
+export type DownswitchReason =
+  | "stall"
+  | "bandwidth"
+  | "fatal-error"
+  | "startup"
+  | "codec";
+
+// stalls just after a seek are expected on any network (the target
+// position is rarely buffered), so they get a longer budget and are
+// kept out of the cumulative window
+const SEEK_GRACE_MS = 2000;
+// a single unresolved stall episode this long triggers a downswitch
+const SINGLE_STALL_DOWNSWITCH_MS = 4000;
+// seek-adjacent episodes only trigger once clearly beyond load latency
+const GRACED_STALL_DOWNSWITCH_MS = 10000;
+// total (non-graced) stall time within the rolling window that triggers
+const CUMULATIVE_STALL_DOWNSWITCH_MS = 7000;
+// rolling window for cumulative stall accounting; long enough to catch
+// chronic short stalls, short enough that ancient history ages out
+const STALL_WINDOW_MS = 60000;
+// a throughput sample below bitrate * margin counts as evidence the
+// connection cannot sustain the stream
+const PREDICTIVE_BANDWIDTH_MARGIN = 1.1;
+// consecutive low samples required for a predictive (pre-stall) downswitch
+const PREDICTIVE_SAMPLE_COUNT = 3;
+// measured throughput must clear the original stream's bitrate by this
+// margin before a downswitched player retries full quality
+const RETRY_BANDWIDTH_MARGIN = 1.5;
+// the stall clock is blind before playback starts (the player is still
+// paused), so the initial load needs its own budget
+const STARTUP_DOWNSWITCH_MS = 10000;
+// no realistic original recording stream plays comfortably below this,
+// so a camera whose bitrate is not yet known starts low
+const KNOWN_SLOW_START_FLOOR_BPS = 3_000_000;
+// the first sample is biased toward the seeded default estimate
+const PROBE_MIN_SUB_SAMPLES = 2;
+
+type StallEpisode = {
+  start: number;
+  end: number;
+};
+
+export class AutoQualityGovernor {
+  // returns false when quality is pinned, sub is unavailable, or the
+  // player is already low
+  private requestDownswitch: (reason: DownswitchReason) => boolean;
+  private requestUpswitch: (() => void) | undefined;
+
+  private episodes: StallEpisode[] = [];
+  private openEpisode: { start: number; graced: boolean } | null = null;
+  private stallTimer: ReturnType<typeof setTimeout> | undefined;
+  private startupTimer: ReturnType<typeof setTimeout> | undefined;
+  private lastSeekTs = 0;
+  private consecutiveLowSamples = 0;
+  private upswitchProbeArmed = false;
+  private probeSampleCount = 0;
+  private mainUnplayable = false;
+  private holdLow = false;
+
+  // network facts survive stall-history resets: a manual pin or camera
+  // switch does not change what the connection can carry
+  private bandwidthEstimateBps: number | undefined;
+  private mainBitrateBps: number | undefined;
+
+  constructor(
+    requestDownswitch: (reason: DownswitchReason) => boolean,
+    requestUpswitch?: () => void,
+  ) {
+    this.requestDownswitch = requestDownswitch;
+    this.requestUpswitch = requestUpswitch;
+  }
+
+  get bandwidthEstimate(): number | undefined {
+    return this.bandwidthEstimateBps;
+  }
+
+  /** Seed the connection estimate persisted from earlier sessions. */
+  seed(bandwidthEstimateBps: number | undefined) {
+    if (this.bandwidthEstimateBps === undefined) {
+      this.bandwidthEstimateBps = bandwidthEstimateBps;
+    }
+  }
+
+  /**
+   * Suppresses every path that would route playback back onto the
+   * original stream.
+   */
+  markMainUnplayable() {
+    this.mainUnplayable = true;
+  }
+
+  get isMainUnplayable(): boolean {
+    return this.mainUnplayable;
+  }
+
+  /**
+   * Hold playback on the low stream regardless of measured headroom
+   * (user preference such as data saver, not a bandwidth fact).
+   */
+  setHoldLow(hold: boolean) {
+    this.holdLow = hold;
+  }
+
+  /**
+   * Record the original stream's advertised bitrate learned outside of
+   * playback (e.g. parsed from its master playlist). Live measurements
+   * take precedence.
+   */
+  learnMainBitrate(bitrateBps: number) {
+    if (this.mainBitrateBps === undefined && bitrateBps > 0) {
+      this.mainBitrateBps = bitrateBps;
+    }
+  }
+
+  /**
+   * Starts the time-to-first-frame budget: no stall episode can exist
+   * before playback starts, so a first segment too large for the
+   * connection would otherwise spin forever.
+   */
+  sourceLoadStarted() {
+    clearTimeout(this.startupTimer);
+    this.startupTimer = setTimeout(
+      () => this.triggerDownswitch("startup"),
+      STARTUP_DOWNSWITCH_MS,
+    );
+  }
+
+  sourceLoadEnded() {
+    clearTimeout(this.startupTimer);
+    this.startupTimer = undefined;
+  }
+
+  /**
+   * Arm the one-shot upswitch probe after a conservative low start.
+   * Stays armed until it fires or a manual pin resets it, so a
+   * connection that improves later still recovers mid-chunk.
+   */
+  armUpswitchProbe() {
+    this.upswitchProbeArmed = true;
+    this.probeSampleCount = 0;
+  }
+
+  noteSeek() {
+    this.lastSeekTs = Date.now();
+  }
+
+  /**
+   * A stall episode began (hls.js BUFFER_STALLED_ERROR or a video
+   * element waiting event). Idempotent while an episode is open, so the
+   * two signal sources need no cross-coordination.
+   */
+  stallStarted() {
+    if (this.openEpisode) {
+      return;
+    }
+
+    const now = Date.now();
+    const graced = now - this.lastSeekTs < SEEK_GRACE_MS;
+    this.openEpisode = { start: now, graced };
+
+    // fire mid-stall: either this episode alone exceeds its budget, or
+    // it pushes the window's cumulative stall time over the threshold
+    const singleBudget = graced
+      ? GRACED_STALL_DOWNSWITCH_MS
+      : SINGLE_STALL_DOWNSWITCH_MS;
+    const cumulativeBudget = graced
+      ? Number.POSITIVE_INFINITY
+      : Math.max(0, CUMULATIVE_STALL_DOWNSWITCH_MS - this.windowStallMs(now));
+    this.stallTimer = setTimeout(
+      () => this.triggerDownswitch("stall"),
+      Math.min(singleBudget, cumulativeBudget),
+    );
+  }
+
+  /**
+   * Playback resumed (STALL_RESOLVED, playing, timeupdate) or paused.
+   * Closes any open episode; graced episodes never enter the window.
+   */
+  stallEnded() {
+    if (!this.openEpisode) {
+      return;
+    }
+
+    clearTimeout(this.stallTimer);
+    this.stallTimer = undefined;
+
+    const now = Date.now();
+    if (!this.openEpisode.graced && now > this.openEpisode.start) {
+      this.episodes.push({ start: this.openEpisode.start, end: now });
+    }
+    this.openEpisode = null;
+    this.pruneEpisodes(now);
+  }
+
+  /**
+   * A segment finished loading. Records throughput, refreshes the
+   * original stream's bitrate while playing it, and downswitches
+   * predictively when sustained throughput cannot carry the stream.
+   */
+  bandwidthSample(
+    estimateBps: number,
+    levelBitrateBps: number | undefined,
+    playingMain: boolean,
+  ) {
+    if (!Number.isFinite(estimateBps) || estimateBps <= 0) {
+      return;
+    }
+
+    this.bandwidthEstimateBps = estimateBps;
+
+    if (!playingMain) {
+      this.consecutiveLowSamples = 0;
+      this.probeSampleCount += 1;
+      if (
+        this.upswitchProbeArmed &&
+        !this.mainUnplayable &&
+        !this.holdLow &&
+        this.probeSampleCount >= PROBE_MIN_SUB_SAMPLES &&
+        this.mainBitrateBps !== undefined &&
+        estimateBps > this.mainBitrateBps * RETRY_BANDWIDTH_MARGIN
+      ) {
+        this.upswitchProbeArmed = false;
+        this.requestUpswitch?.();
+      }
+      return;
+    }
+
+    if (levelBitrateBps === undefined || levelBitrateBps <= 0) {
+      return;
+    }
+
+    this.mainBitrateBps = levelBitrateBps;
+
+    if (estimateBps < levelBitrateBps * PREDICTIVE_BANDWIDTH_MARGIN) {
+      this.consecutiveLowSamples += 1;
+      if (this.consecutiveLowSamples >= PREDICTIVE_SAMPLE_COUNT) {
+        this.consecutiveLowSamples = 0;
+        this.triggerDownswitch("bandwidth");
+      }
+    } else {
+      this.consecutiveLowSamples = 0;
+    }
+  }
+
+  /**
+   * hls.js gave up loading (retries exhausted). Returns whether a
+   * downswitch happened so the player knows to attempt recovery instead.
+   */
+  fatalNetworkError(): boolean {
+    return this.triggerDownswitch("fatal-error");
+  }
+
+  /**
+   * Unlike bandwidth signals a codec failure is proof, so the original
+   * stream is marked unplayable before the downswitch. Returns whether
+   * a downswitch happened.
+   */
+  fatalCodecError(): boolean {
+    this.mainUnplayable = true;
+    return this.triggerDownswitch("codec");
+  }
+
+  /**
+   * Whether a downswitched player should retry full quality at the next
+   * chunk boundary. Native HLS playback reports no segment stats, so
+   * without bandwidth evidence this falls back to a clean stall window.
+   */
+  shouldRetryMain(): boolean {
+    if (this.mainUnplayable || this.holdLow) {
+      return false;
+    }
+
+    if (
+      this.bandwidthEstimateBps !== undefined &&
+      this.mainBitrateBps !== undefined
+    ) {
+      return (
+        this.bandwidthEstimateBps > this.mainBitrateBps * RETRY_BANDWIDTH_MARGIN
+      );
+    }
+
+    return this.windowStallMs(Date.now()) === 0;
+  }
+
+  /**
+   * Whether playback should begin on the low quality stream based on
+   * persisted network knowledge. A fully-cold device returns false; the
+   * owner handles that case with a conservative start plus the probe.
+   */
+  shouldStartLow(): boolean {
+    if (this.bandwidthEstimateBps === undefined) {
+      return false;
+    }
+
+    if (this.mainBitrateBps !== undefined) {
+      return (
+        this.bandwidthEstimateBps <
+        this.mainBitrateBps * PREDICTIVE_BANDWIDTH_MARGIN
+      );
+    }
+
+    // unknown camera bitrate: above the floor, start on the original
+    // and let the startup budget correct a wrong guess
+    return this.bandwidthEstimateBps < KNOWN_SLOW_START_FLOOR_BPS;
+  }
+
+  /** A manual pin invalidates stall history but not network facts. */
+  resetStallHistory() {
+    clearTimeout(this.stallTimer);
+    this.stallTimer = undefined;
+    clearTimeout(this.startupTimer);
+    this.startupTimer = undefined;
+    this.openEpisode = null;
+    this.episodes = [];
+    this.consecutiveLowSamples = 0;
+    this.upswitchProbeArmed = false;
+    this.probeSampleCount = 0;
+  }
+
+  /**
+   * A camera switch additionally invalidates the per-camera facts: the
+   * stream bitrate and codec playability. The holdLow preference is
+   * device-level and survives.
+   */
+  resetForCamera() {
+    this.resetStallHistory();
+    this.mainBitrateBps = undefined;
+    this.mainUnplayable = false;
+  }
+
+  destroy() {
+    this.resetStallHistory();
+  }
+
+  private triggerDownswitch(reason: DownswitchReason): boolean {
+    const handled = this.requestDownswitch(reason);
+    if (handled) {
+      // the low stream starts with a clean record
+      this.resetStallHistory();
+    }
+    return handled;
+  }
+
+  private windowStallMs(now: number): number {
+    this.pruneEpisodes(now);
+    const windowStart = now - STALL_WINDOW_MS;
+    let total = 0;
+    for (const episode of this.episodes) {
+      total += episode.end - Math.max(episode.start, windowStart);
+    }
+    if (this.openEpisode && !this.openEpisode.graced) {
+      total += now - Math.max(this.openEpisode.start, windowStart);
+    }
+    return total;
+  }
+
+  private pruneEpisodes(now: number) {
+    const windowStart = now - STALL_WINDOW_MS;
+    this.episodes = this.episodes.filter(
+      (episode) => episode.end > windowStart,
+    );
+  }
+}

web/src/components/player/dynamic/DynamicVideoController.ts

@@ -10,6 +10,10 @@ import { playWithTemporaryMuteFallback } from "@/utils/videoUtil.ts";
 
 type PlayerMode = "playback" | "scrubbing";
 
+// how long a seek may wait for its `seeked` event before playback starts
+// anyway; long enough that a normally completing seek always wins
+const SEEK_PLAY_FALLBACK_MS = 1000;
+
 export class DynamicVideoController {
   // main state
   public camera = "";
@@ -24,7 +28,6 @@ export class DynamicVideoController {
   private timeRange: TimeRange = { after: 0, before: 0 };
   private inpointOffset: number = 0;
   private annotationOffset: number;
-  private timeToStart: number | undefined = undefined;
 
   constructor(
     camera: string,
@@ -51,11 +54,6 @@ export class DynamicVideoController {
       this.timeRange.after,
       this.recordings[0],
     );
-
-    if (this.timeToStart) {
-      this.seekToTimestamp(this.timeToStart);
-      this.timeToStart = undefined;
-    }
   }
 
   play() {
@@ -71,8 +69,11 @@ export class DynamicVideoController {
   }
 
   seekToTimestamp(time: number, play: boolean = false) {
+    // a seek outside the current playback window is a no-op: the view
+    // moves its anchor and chunk on such seeks, and the rebuilt source
+    // resumes at the anchor (startPosition plus the post-load seek).
+    // Seeking here would only reposition the outgoing source's media
     if (time < this.timeRange.after || time > this.timeRange.before) {
-      this.timeToStart = time;
       return;
     }
 
@@ -91,22 +92,33 @@ export class DynamicVideoController {
       return;
     }
 
-    if (seekSeconds != 0) {
-      this.playerController.currentTime = seekSeconds;
-
+    if (this.playerController.currentTime === seekSeconds) {
+      // seeking to the current position fires no seeked event, so apply
+      // the play intent directly (this includes position 0, which the
+      // player sits at before its first seek)
       if (play) {
-        this.waitAndPlay();
+        playWithTemporaryMuteFallback(this.playerController);
       } else {
         this.playerController.pause();
       }
+      return;
+    }
+
+    this.playerController.currentTime = seekSeconds;
+
+    if (play) {
+      this.waitAndPlay();
     } else {
-      // no op
+      this.playerController.pause();
     }
   }
 
   waitAndPlay() {
     return new Promise((resolve) => {
+      let fallback: NodeJS.Timeout | undefined;
+
       const onSeekedHandler = () => {
+        clearTimeout(fallback);
         this.playerController.removeEventListener("seeked", onSeekedHandler);
         playWithTemporaryMuteFallback(this.playerController);
         resolve(undefined);
@@ -115,6 +127,12 @@ export class DynamicVideoController {
       this.playerController.addEventListener("seeked", onSeekedHandler, {
         once: true,
       });
+
+      // iOS ManagedMediaSource pauses hls.js buffering, so `seeked` may
+      // never fire; playing is what prompts WebKit to resume streaming
+      if ("ManagedMediaSource" in window) {
+        fallback = setTimeout(onSeekedHandler, SEEK_PLAY_FALLBACK_MS);
+      }
     });
   }
 
@@ -126,20 +144,26 @@ export class DynamicVideoController {
 
   getProgress(playerTime: number): number {
     // take a player time in seconds and convert to timestamp in timeline
-    let timestamp = 0;
+    const recordings = this.recordings || [];
     let totalTime = 0;
-    (this.recordings || []).every((segment) => {
+    for (const segment of recordings) {
       if (totalTime + segment.duration > playerTime) {
-        // segment is here
-        timestamp = segment.start_time + (playerTime - totalTime);
-        return false;
-      } else {
-        totalTime += segment.duration;
-        return true;
+        // playlist media from before the span's wall start (keyframe
+        // back-snap lead-in) clamps to the span start
+        const wallLength = segment.end_time - segment.start_time;
+        const leadIn = Math.max(0, segment.duration - wallLength);
+        return (
+          segment.start_time + Math.max(0, playerTime - totalTime - leadIn)
+        );
       }
-    });
+      totalTime += segment.duration;
+    }
 
-    return timestamp;
+    // past the modeled total: clamp to the covered end rather than
+    // reporting wall-clock zero
+    return recordings.length > 0
+      ? recordings[recordings.length - 1].end_time
+      : 0;
   }
 
   scrubToTimestamp(time: number, saveIfNotReady: boolean = false) {
@@ -149,7 +173,10 @@ export class DynamicVideoController {
       this.previewController.setNewPreviewStartTime(time);
     }
 
-    if (scrubResult && this.playerMode != "scrubbing") {
+    // pause even when no preview can render this range: a hidden player
+    // left running reports stale times once the drag releases, bouncing
+    // the handlebar back and sometimes swallowing the release seek
+    if (this.playerMode != "scrubbing") {
       this.playerMode = "scrubbing";
       this.playerController.pause();
     }

web/src/components/player/dynamic/DynamicVideoPlayer.tsx

@@ -9,7 +9,12 @@ import {
 import { useApiHost } from "@/api";
 import useSWR from "swr";
 import { FrigateConfig } from "@/types/frigateConfig";
-import { Recording } from "@/types/record";
+import {
+  AutoQualityReason,
+  PlaybackQuality,
+  Recording,
+  RecordingCoverage,
+} from "@/types/record";
 import { Preview } from "@/types/preview";
 import PreviewPlayer, { PreviewController } from "../PreviewPlayer";
 import { DynamicVideoController } from "./DynamicVideoController";
@@ -32,6 +37,13 @@ import {
   grabVideoSnapshot,
 } from "@/utils/snapshotUtil";
 import { isFirefox } from "react-device-detect";
+import { AutoQualityGovernor } from "./AutoQualityGovernor";
+import { isCodecFamilySupported } from "@/utils/codecSupport";
+import { useUserPersistence } from "@/hooks/use-user-persistence";
+
+// forward buffer while playing the low quality stream; low bitrate makes
+// a longer buffer cheap and it rides out connection variance better
+const SUB_STREAM_BUFFER_LENGTH_S = 30;
 
 /**
  * Dynamically switches between video playback and scrubbing preview player.
@@ -55,6 +67,11 @@ type DynamicVideoPlayerProps = {
   toggleFullscreen: () => void;
   containerRef?: React.MutableRefObject<HTMLDivElement | null>;
   transformedOverlay?: ReactNode;
+  quality?: PlaybackQuality;
+  onAutoQualityChange?: (
+    lowQuality: boolean,
+    reason: AutoQualityReason | undefined,
+  ) => void;
 };
 export default function DynamicVideoPlayer({
   className,
@@ -75,6 +92,8 @@ export default function DynamicVideoPlayer({
   toggleFullscreen,
   containerRef,
   transformedOverlay,
+  quality,
+  onAutoQualityChange,
 }: DynamicVideoPlayerProps) {
   const { t } = useTranslation(["components/player", "views/live"]);
   const apiHost = useApiHost();
@@ -128,7 +147,7 @@ export default function DynamicVideoPlayer({
 
   const [isLoading, setIsLoading] = useState(false);
   const [isBuffering, setIsBuffering] = useState(false);
-  const [loadingTimeout, setLoadingTimeout] = useState<NodeJS.Timeout>();
+  const loadingTimeoutRef = useRef<NodeJS.Timeout | undefined>(undefined);
 
   // Don't set source until recordings load - we need accurate startPosition
   // to avoid hls.js clamping to video end when startPosition exceeds duration
@@ -138,32 +157,80 @@ export default function DynamicVideoPlayer({
 
   useEffect(() => {
     if (!isScrubbing) {
-      setLoadingTimeout(setTimeout(() => setIsLoading(true), 1000));
+      loadingTimeoutRef.current = setTimeout(() => setIsLoading(true), 1000);
     }
 
     return () => {
-      if (loadingTimeout) {
-        clearTimeout(loadingTimeout);
+      if (loadingTimeoutRef.current) {
+        clearTimeout(loadingTimeoutRef.current);
       }
     };
-    // we only want trigger when scrubbing state changes
-    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [camera, isScrubbing]);
 
+  // wall-clock position to resume from once the current source finishes
+  // loading. A seek landing mid-load must win over the position the
+  // source was built around, or the post-load seek drags playback back
+  const sourceAnchorRef = useRef<number | undefined>(undefined);
+
+  useEffect(() => {
+    sourceAnchorRef.current = startTimestamp;
+  }, [startTimestamp]);
+  // a recordings change refined the seek model without changing the
+  // playlist, so the playback effect skips its loading indicator
+  const modelOnlyUpdateRef = useRef(false);
+
   const onPlayerLoaded = useCallback(() => {
-    if (!controller || !startTimestamp) {
+    sourceLoadedRef.current = true;
+    governorRef.current?.sourceLoadEnded();
+
+    const anchor = sourceAnchorRef.current;
+
+    if (!controller || !anchor) {
       return;
     }
 
-    controller.seekToTimestamp(startTimestamp, true);
-  }, [startTimestamp, controller]);
+    // an anchor outside this chunk is stale (e.g. a natural clip
+    // advance); the playlist already starts where playback should
+    if (anchor < timeRange.after || anchor > timeRange.before) {
+      return;
+    }
+
+    // while the handlebar is down only position the hidden player, never
+    // start it: a mid-drag chunk prefetch can audibly blip before
+    // onPlaying pauses it. The release seek starts playback
+    controller.seekToTimestamp(anchor, !isScrubbing);
+  }, [controller, timeRange, isScrubbing]);
+
+  // used to re-anchor the source when an auto quality switch rebuilds
+  // the playlist mid-playback
+  const lastPlayedTimestampRef = useRef<number | undefined>(undefined);
+
+  // the range the controller's playback model was last built for; while
+  // a chunk change awaits its coverage, the outgoing source reports
+  // times that would map through the stale model
+  const modelTimeRangeRef = useRef<TimeRange | undefined>(undefined);
 
   const onTimeUpdate = useCallback(
     (time: number) => {
+      // safety net for stall or startup signals the player missed
+      governorRef.current?.stallEnded();
+      if (!sourceLoadedRef.current) {
+        sourceLoadedRef.current = true;
+        governorRef.current?.sourceLoadEnded();
+      }
+
       if (isScrubbing || !controller || !onTimestampUpdate || time == 0) {
         return;
       }
 
+      // drop reports until the controller's model matches this chunk
+      if (
+        modelTimeRangeRef.current?.after !== timeRange.after ||
+        modelTimeRangeRef.current?.before !== timeRange.before
+      ) {
+        return;
+      }
+
       if (isLoading) {
         setIsLoading(false);
       }
@@ -172,9 +239,18 @@ export default function DynamicVideoPlayer({
         setIsBuffering(false);
       }
 
-      onTimestampUpdate(controller.getProgress(time));
+      const progress = controller.getProgress(time);
+      lastPlayedTimestampRef.current = progress;
+      onTimestampUpdate(progress);
     },
-    [controller, onTimestampUpdate, isBuffering, isLoading, isScrubbing],
+    [
+      controller,
+      onTimestampUpdate,
+      isBuffering,
+      isLoading,
+      isScrubbing,
+      timeRange,
+    ],
   );
 
   const onUploadFrameToPlus = useCallback(
@@ -238,45 +314,350 @@ export default function DynamicVideoPlayer({
     () => ({
       before: timeRange.before,
       after: timeRange.after,
+      timelines: true,
     }),
     [timeRange],
   );
-  const { data: recordings } = useSWR<Recording[]>(
-    [`${camera}/recordings`, recordingParams],
+  const { data: coverage } = useSWR<RecordingCoverage>(
+    [`${camera}/recordings/coverage`, recordingParams],
     { revalidateOnFocus: false },
   );
 
+  // auto quality plays the default route until the governor downswitches
+  // to the pinned sub route; manual pins bypass this entirely
+  const [autoLowQuality, setAutoLowQuality] = useState(false);
+  const [autoLowReason, setAutoLowReason] = useState<
+    AutoQualityReason | undefined
+  >(undefined);
+  const autoLowQualityRef = useRef(false);
+
+  const subAvailable = useMemo(
+    () =>
+      coverage?.spans?.some((span) => span.streams.includes("sub")) ?? false,
+    [coverage],
+  );
+
+  const resolvedQuality = quality ?? "auto";
+
+  // the ref indirection keeps these reading fresh state while the
+  // governor stays a single instance for the component's lifetime
+  const tryDownswitchRef = useRef<(reason: string) => boolean>(() => false);
+  const tryUpswitchRef = useRef<() => void>(() => {});
+  const governorRef = useRef<AutoQualityGovernor | null>(null);
+  if (governorRef.current === null) {
+    governorRef.current = new AutoQualityGovernor(
+      (reason) => tryDownswitchRef.current(reason),
+      () => tryUpswitchRef.current(),
+    );
+  }
+  const governor = governorRef.current;
+
+  // callers pass an inline callback, so keeping it out of the notify
+  // effect's deps stops the notification's re-render from re-firing it
+  const onAutoQualityChangeRef = useRef(onAutoQualityChange);
+
   useEffect(() => {
+    onAutoQualityChangeRef.current = onAutoQualityChange;
+  }, [onAutoQualityChange]);
+
+  useEffect(() => {
+    autoLowQualityRef.current = autoLowQuality;
+    onAutoQualityChangeRef.current?.(
+      autoLowQuality,
+      autoLowQuality ? autoLowReason : undefined,
+    );
+  }, [autoLowQuality, autoLowReason]);
+
+  useEffect(() => {
+    tryDownswitchRef.current = (reason: string) => {
+      if (
+        resolvedQuality !== "auto" ||
+        !subAvailable ||
+        autoLowQualityRef.current
+      ) {
+        return false;
+      }
+      setAutoLowQuality(true);
+      setAutoLowReason(reason === "codec" ? "codec" : "bandwidth");
+      // so a recovered connection (or a wrong downswitch) returns to
+      // full quality mid-chunk rather than at the next boundary
+      governor.armUpswitchProbe();
+      return true;
+    };
+    tryUpswitchRef.current = () => {
+      if (resolvedQuality === "auto" && autoLowQualityRef.current) {
+        setAutoLowQuality(false);
+        setAutoLowReason(undefined);
+      }
+    };
+  }, [resolvedQuality, subAvailable, governor]);
+
+  // persisted across sessions so a device on a known-slow connection
+  // starts low instead of paying the first stall to find out
+  const [persistedEstimate, setPersistedEstimate, estimateLoaded] =
+    useUserPersistence<number>("playbackBandwidthEstimate");
+
+  const persistGovernor = useCallback(() => {
+    const estimate = governor.bandwidthEstimate;
+    if (estimate !== undefined) {
+      setPersistedEstimate(Math.round(estimate));
+    }
+  }, [governor, setPersistedEstimate]);
+  const persistGovernorRef = useRef(persistGovernor);
+
+  useEffect(() => {
+    persistGovernorRef.current = persistGovernor;
+  }, [persistGovernor]);
+
+  useEffect(() => {
+    // returning to auto starts fresh on the default route, except when
+    // this browser already proved it cannot decode the original stream
+    governor.resetStallHistory();
+    setAutoLowQuality(governor.isMainUnplayable);
+    setAutoLowReason(governor.isMainUnplayable ? "codec" : undefined);
+    // we only want to reset when the pinned quality changes
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [quality]);
+
+  useEffect(() => {
+    // measured connection throughput carries over across cameras
+    governor.resetForCamera();
+    setAutoLowQuality(false);
+    setAutoLowReason(undefined);
+    // we only want to reset when the camera changes
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [camera]);
+
+  // seed the governor once per camera, then decide the starting quality
+  const seededCameraRef = useRef<string | null>(null);
+  useEffect(() => {
+    if (seededCameraRef.current === camera || !estimateLoaded || !coverage) {
+      return;
+    }
+    seededCameraRef.current = camera;
+
+    const mainSummary = coverage.streams?.main;
+    if (mainSummary?.bitrate) {
+      governor.learnMainBitrate(mainSummary.bitrate);
+    }
+    governor.seed(persistedEstimate);
+
+    if (resolvedQuality !== "auto" || !subAvailable) {
+      return;
+    }
+
+    // data saver is a user preference, not a bandwidth fact: hold the
+    // low stream and never auto-upswitch against it (a manual pin to
+    // Original still wins as an explicit action)
+    const saveData =
+      (navigator as Navigator & { connection?: { saveData?: boolean } })
+        .connection?.saveData === true;
+    if (saveData) {
+      governor.setHoldLow(true);
+    }
+
+    // a browser that cannot decode the original codec can never play
+    // the merged route. This probe fails open (unknown codecs count as
+    // supported); the reactive fatal-codec path is the real authority
+    const mainSupported = isCodecFamilySupported(mainSummary?.video_codec);
+    const subSupported = isCodecFamilySupported(
+      coverage.streams?.sub?.video_codec,
+    );
+    if (!mainSupported && subSupported) {
+      governor.markMainUnplayable();
+      setAutoLowQuality(true);
+      setAutoLowReason("codec");
+      return;
+    }
+
+    if (saveData) {
+      setAutoLowQuality(true);
+      setAutoLowReason("saveData");
+      return;
+    }
+
+    // a fully cold device also starts low: the conservative start shows
+    // a first frame in seconds and the armed probe recovers full
+    // quality within a few segment loads on connections that allow it
+    const coldStart = governor.bandwidthEstimate === undefined;
+    if (!coldStart && !governor.shouldStartLow()) {
+      return;
+    }
+
+    setAutoLowQuality(true);
+    setAutoLowReason("bandwidth");
+    governor.armUpswitchProbe();
+  }, [
+    camera,
+    coverage,
+    estimateLoaded,
+    persistedEstimate,
+    resolvedQuality,
+    subAvailable,
+    governor,
+  ]);
+
+  // time-to-first-frame budget; the stall clock is blind before
+  // playback starts, so an oversized first segment would spin forever
+  const sourceLoadedRef = useRef(false);
+  useEffect(() => {
+    sourceLoadedRef.current = false;
+  }, [source]);
+  useEffect(() => {
+    if (!source || isScrubbing || sourceLoadedRef.current) {
+      governor.sourceLoadEnded();
+      return;
+    }
+    governor.sourceLoadStarted();
+  }, [source, isScrubbing, governor]);
+
+  useEffect(() => {
+    // a chunk boundary is where full quality may be retried, and a
+    // natural point to persist what the governor has learned
+    setAutoLowQuality((prev) => prev && !governor.shouldRetryMain());
+    persistGovernorRef.current();
+    // we only want to re-evaluate when the playback chunk changes
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [timeRange]);
+
+  useEffect(() => {
+    return () => {
+      persistGovernorRef.current();
+      governor.destroy();
+    };
+    // governor is a stable per-mount instance
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  const effectiveQuality: PlaybackQuality =
+    resolvedQuality === "auto" && autoLowQuality ? "sub" : resolvedQuality;
+
+  const onStallStart = useCallback(() => governor.stallStarted(), [governor]);
+  const onStallEnd = useCallback(() => governor.stallEnded(), [governor]);
+  const onSeekStart = useCallback(() => governor.noteSeek(), [governor]);
+  const onFatalNetworkError = useCallback(
+    () => governor.fatalNetworkError(),
+    [governor],
+  );
+  const onFatalCodecError = useCallback(
+    () => governor.fatalCodecError(),
+    [governor],
+  );
+  const onBandwidthSample = useCallback(
+    (estimateBps: number, levelBitrateBps?: number) =>
+      governor.bandwidthSample(
+        estimateBps,
+        levelBitrateBps,
+        // the merged default route leads with the original stream, so
+        // its samples measure original-quality sustainability
+        effectiveQuality !== "sub",
+      ),
+    [governor, effectiveQuality],
+  );
+
+  // the realized timelines mirror the vod manifests exactly, including
+  // keyframe back-snap lead-in at cross-stream hand-offs. Walking wall
+  // lengths instead drifts ~0.5s per hand-off, since the playlist
+  // contains lead-in media the model never knew about
+  const recordings = useMemo<Recording[] | undefined>(() => {
+    const timeline =
+      coverage?.timelines?.[
+        effectiveQuality === "main" || effectiveQuality === "sub"
+          ? effectiveQuality
+          : "auto"
+      ];
+
+    if (!timeline) {
+      return undefined;
+    }
+
+    return timeline.map((span) => ({
+      start_time: span.start_time,
+      end_time: span.end_time,
+      duration: span.duration / 1000,
+    })) as Recording[];
+  }, [coverage, effectiveQuality]);
+
+  // lets the effect below tell quality rebuilds apart from chunk changes
+  const prevEffectiveQualityRef = useRef(effectiveQuality);
+
+  useEffect(() => {
+    const qualityChanged = prevEffectiveQualityRef.current !== effectiveQuality;
+    prevEffectiveQualityRef.current = effectiveQuality;
+
     if (!recordings?.length) {
       if (recordings?.length == 0) {
+        // drop any stale source so the previous playlist unmounts
+        // instead of playing under the no-recording state
+        setSource(undefined);
         setNoRecording(true);
+        // with no source nothing will play to clear a pending
+        // camera-switch load, hiding the message behind a preview frame
+        if (loadingTimeoutRef.current) {
+          clearTimeout(loadingTimeoutRef.current);
+        }
+        setIsLoading(false);
       }
 
       return;
     }
 
+    // an identical playlist means coverage only refined the seek model;
+    // skip the rebuild so the player is not torn down
+    const streamPath =
+      effectiveQuality === "main" || effectiveQuality === "sub"
+        ? `/${effectiveQuality}`
+        : "";
+    const playlist = `${apiHost}vod/${camera}${streamPath}/start/${recordingParams.after}/end/${recordingParams.before}/master.m3u8`;
+    if (!qualityChanged && source?.playlist === playlist) {
+      modelOnlyUpdateRef.current = true;
+      return;
+    }
+
+    // a quality switch rebuilds mid-playback, so anchor to the live
+    // playhead rather than the chunk-stale startTimestamp prop. The
+    // controller still holds the OUTGOING timeline here (newPlayback
+    // runs in a later effect), and the timeupdate-throttled lastPlayed
+    // ref lags the frame on screen by up to ~250ms
+    const liveTime = playerRef.current?.currentTime;
+    const livePlayed =
+      qualityChanged && controller && liveTime !== undefined && liveTime > 0
+        ? controller.getProgress(liveTime)
+        : undefined;
+    const lastPlayed = livePlayed ?? lastPlayedTimestampRef.current;
+    const anchorTimestamp =
+      qualityChanged &&
+      lastPlayed !== undefined &&
+      lastPlayed >= timeRange.after &&
+      lastPlayed <= timeRange.before
+        ? lastPlayed
+        : startTimestamp;
+    sourceAnchorRef.current = anchorTimestamp;
+
     let startPosition = undefined;
 
-    if (startTimestamp) {
+    if (anchorTimestamp) {
       const inpointOffset = calculateInpointOffset(
         recordingParams.after,
         (recordings || [])[0],
       );
 
       startPosition = calculateSeekPosition(
-        startTimestamp,
+        anchorTimestamp,
         recordings,
         inpointOffset,
       );
     }
 
     setSource({
-      playlist: `${apiHost}vod/${camera}/start/${recordingParams.after}/end/${recordingParams.before}/master.m3u8`,
+      playlist,
       startPosition,
     });
 
+    // we only want to rebuild the source when the playlist itself changes;
+    // startTimestamp, timeRange, and the anchor refs are read as-of-rebuild
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [recordings]);
+  }, [recordings, effectiveQuality]);
 
   useEffect(() => {
     if (!controller || !recordings?.length) {
@@ -287,12 +668,28 @@ export default function DynamicVideoPlayer({
       playerRef.current.autoplay = !isScrubbing;
     }
 
-    setLoadingTimeout(setTimeout(() => setIsLoading(true), 1000));
+    const modelOnlyUpdate = modelOnlyUpdateRef.current;
+    modelOnlyUpdateRef.current = false;
+
+    // on a source swap the element already has a decoded frame; keep it
+    // visible under the buffering indicator rather than hiding it
+    // behind the preview player like the initial load does
+    const hasDecodedFrame =
+      (playerRef.current?.readyState ?? 0) >=
+      HTMLMediaElement.HAVE_CURRENT_DATA;
+
+    if (!modelOnlyUpdate) {
+      loadingTimeoutRef.current = setTimeout(
+        () => (hasDecodedFrame ? setIsBuffering(true) : setIsLoading(true)),
+        1000,
+      );
+    }
 
     controller.newPlayback({
       recordings: recordings ?? [],
       timeRange,
     });
+    modelTimeRangeRef.current = timeRange;
 
     // we only want this to change when controller or recordings update
     // eslint-disable-next-line react-hooks/exhaustive-deps
@@ -356,8 +753,8 @@ export default function DynamicVideoPlayer({
               playerRef.current?.pause();
             }
 
-            if (loadingTimeout) {
-              clearTimeout(loadingTimeout);
+            if (loadingTimeoutRef.current) {
+              clearTimeout(loadingTimeoutRef.current);
             }
 
             setNoRecording(false);
@@ -372,6 +769,16 @@ export default function DynamicVideoPlayer({
               setIsBuffering(true);
             }
           }}
+          onStallStart={onStallStart}
+          onStallEnd={onStallEnd}
+          onSeekStart={onSeekStart}
+          onBandwidthSample={onBandwidthSample}
+          onFatalNetworkError={onFatalNetworkError}
+          onFatalCodecError={onFatalCodecError}
+          initialBandwidthEstimate={governor.bandwidthEstimate}
+          bufferLength={
+            effectiveQuality === "sub" ? SUB_STREAM_BUFFER_LENGTH_S : undefined
+          }
           isDetailMode={isDetailMode}
           camera={contextCamera || camera}
           currentTimeOverride={currentTime}

web/src/components/settings/wizard/Step3StreamConfig.tsx

@@ -45,6 +45,13 @@ import {
   CommandList,
 } from "@/components/ui/command";
 
+// Recording the sub stream from the same stream as record would just
+// re-record the main stream, so the two roles are mutually exclusive.
+const CONFLICTING_ROLES: Partial<Record<StreamRole, StreamRole>> = {
+  record: "record_sub",
+  record_sub: "record",
+};
+
 type Step3StreamConfigProps = {
   wizardData: Partial<WizardFormData>;
   onUpdate: (data: Partial<WizardFormData>) => void;
@@ -163,9 +170,12 @@ export default function Step3StreamConfig({
         const newRoles = stream.roles.filter((r) => r !== role);
         updateStream(streamId, { roles: newRoles });
       } else {
-        // Check if role is already used in another stream
         const usedRoles = getUsedRolesExcludingStream(streamId);
-        if (!usedRoles.has(role)) {
+        const conflictingRole = CONFLICTING_ROLES[role];
+        const hasConflict = conflictingRole
+          ? stream.roles.includes(conflictingRole)
+          : false;
+        if (!usedRoles.has(role) && !hasConflict) {
           // Allow adding the role
           const newRoles = [...stream.roles, role];
           updateStream(streamId, { roles: newRoles });
@@ -617,6 +627,10 @@ export default function Step3StreamConfig({
                             <strong>record</strong> -{" "}
                             {t("cameraWizard.step3.rolesPopover.record")}
                           </div>
+                          <div>
+                            <strong>record_sub</strong> -{" "}
+                            {t("cameraWizard.step3.rolesPopover.record_sub")}
+                          </div>
                           <div>
                             <strong>audio</strong> -{" "}
                             {t("cameraWizard.step3.rolesPopover.audio")}
@@ -639,25 +653,35 @@ export default function Step3StreamConfig({
                 </div>
                 <div className="rounded-lg bg-background p-3">
                   <div className="flex flex-wrap gap-2">
-                    {(["detect", "record", "audio"] as const).map((role) => {
-                      const isUsedElsewhere = getUsedRolesExcludingStream(
-                        stream.id,
-                      ).has(role);
-                      const isChecked = stream.roles.includes(role);
-                      return (
-                        <div
-                          key={role}
-                          className="flex w-full items-center justify-between"
-                        >
-                          <span className="text-sm capitalize">{role}</span>
-                          <Switch
-                            checked={isChecked}
-                            onCheckedChange={() => toggleRole(stream.id, role)}
-                            disabled={!isChecked && isUsedElsewhere}
-                          />
-                        </div>
-                      );
-                    })}
+                    {(["detect", "record", "record_sub", "audio"] as const).map(
+                      (role) => {
+                        const isUsedElsewhere = getUsedRolesExcludingStream(
+                          stream.id,
+                        ).has(role);
+                        const conflictingRole = CONFLICTING_ROLES[role];
+                        const hasConflict = conflictingRole
+                          ? stream.roles.includes(conflictingRole)
+                          : false;
+                        const isChecked = stream.roles.includes(role);
+                        return (
+                          <div
+                            key={role}
+                            className="flex w-full items-center justify-between"
+                          >
+                            <span className="text-sm capitalize">{role}</span>
+                            <Switch
+                              checked={isChecked}
+                              onCheckedChange={() =>
+                                toggleRole(stream.id, role)
+                              }
+                              disabled={
+                                !isChecked && (isUsedElsewhere || hasConflict)
+                              }
+                            />
+                          </div>
+                        );
+                      },
+                    )}
                   </div>
                 </div>
               </div>

web/src/components/timeline/MotionReviewTimeline.tsx

@@ -42,6 +42,7 @@ export type MotionReviewTimelineProps = {
   events: ReviewSegment[];
   motion_events: MotionData[];
   noRecordingRanges?: RecordingSegment[];
+  subOnlyRanges?: Pick<RecordingSegment, "start_time" | "end_time">[];
   contentRef: RefObject<HTMLDivElement | null>;
   timelineRef?: RefObject<HTMLDivElement | null>;
   onHandlebarDraggingChange?: (isDragging: boolean) => void;
@@ -76,6 +77,7 @@ export function MotionReviewTimeline({
   events,
   motion_events,
   noRecordingRanges,
+  subOnlyRanges,
   contentRef,
   timelineRef,
   onHandlebarDraggingChange,
@@ -122,6 +124,17 @@ export function MotionReviewTimeline({
     [noRecordingRanges],
   );
 
+  const getIsSubOnly = useCallback(
+    (time: number): boolean => {
+      if (subOnlyRanges == undefined) return false;
+
+      return subOnlyRanges.some(
+        (range) => time >= range.start_time && time < range.end_time,
+      );
+    },
+    [subOnlyRanges],
+  );
+
   const segmentTimes = useMemo(() => {
     const segments = [];
     let segmentTime = timelineStartAligned;
@@ -245,6 +258,7 @@ export function MotionReviewTimeline({
         motionOnly={motionOnly}
         getMotionSegmentValue={getMotionSegmentValue}
         getRecordingAvailability={getRecordingAvailability}
+        getIsSubOnly={getIsSubOnly}
         alwaysShowMotionLine={alwaysShowMotionLine}
       />
     </ReviewTimeline>

web/src/components/timeline/MotionSegment.tsx

@@ -5,6 +5,7 @@ import React, { useCallback, useEffect, useMemo, useRef } from "react";
 import { MinimapBounds, Tick, Timestamp } from "./segment-metadata";
 import { useMotionSegmentUtils } from "@/hooks/use-motion-segment-utils";
 import { isMobile } from "react-device-detect";
+import { useTranslation } from "react-i18next";
 import useTapUtils from "@/hooks/use-tap-utils";
 import { cn } from "@/lib/utils";
 
@@ -16,6 +17,7 @@ type MotionSegmentProps = {
   firstHalfMotionValue: number;
   secondHalfMotionValue: number;
   hasRecording?: boolean;
+  isSubOnly?: boolean;
   prevIsNoRecording?: boolean;
   nextIsNoRecording?: boolean;
   motionOnly: boolean;
@@ -36,6 +38,7 @@ export function MotionSegment({
   firstHalfMotionValue,
   secondHalfMotionValue,
   hasRecording,
+  isSubOnly,
   prevIsNoRecording,
   nextIsNoRecording,
   motionOnly,
@@ -47,6 +50,7 @@ export function MotionSegment({
   dense,
   alwaysShowMotionLine = false,
 }: MotionSegmentProps) {
+  const { t } = useTranslation("views/events");
   const severityType = "all";
   const { getSeverity, getReviewed, displaySeverityType } =
     useEventSegmentUtils(segmentDuration, events, severityType);
@@ -194,8 +198,10 @@ export function MotionSegment({
             segmentClasses,
             severity[0] && "bg-gradient-to-r",
             severity[0] && severityColorsBg[severity[0]],
+            isSubOnly && "bg-background/50",
             hasRecording == false && "bg-background",
           )}
+          title={isSubOnly ? t("subOnlyQuality") : undefined}
           onClick={segmentClick}
           onTouchEnd={(event) => handleTouchStart(event, segmentClick)}
         >

web/src/components/timeline/VirtualizedMotionSegments.tsx

@@ -25,6 +25,7 @@ type VirtualizedMotionSegmentsProps = {
   motionOnly: boolean;
   getMotionSegmentValue: (timestamp: number) => number;
   getRecordingAvailability: (timestamp: number) => boolean | undefined;
+  getIsSubOnly: (timestamp: number) => boolean;
   alwaysShowMotionLine: boolean;
 };
 
@@ -58,6 +59,7 @@ export const VirtualizedMotionSegments = forwardRef<
       motionOnly,
       getMotionSegmentValue,
       getRecordingAvailability,
+      getIsSubOnly,
       alwaysShowMotionLine,
     },
     ref,
@@ -161,6 +163,7 @@ export const VirtualizedMotionSegments = forwardRef<
         );
 
         const hasRecording = getRecordingAvailability(segmentTime);
+        const isSubOnly = getIsSubOnly(segmentTime);
 
         // Check if previous and next segments have recordings
         // This is important because in motionOnly mode, the segments array is filtered
@@ -195,6 +198,7 @@ export const VirtualizedMotionSegments = forwardRef<
               firstHalfMotionValue={firstHalfMotionValue}
               secondHalfMotionValue={secondHalfMotionValue}
               hasRecording={hasRecording}
+              isSubOnly={isSubOnly}
               prevIsNoRecording={prevIsNoRecording}
               nextIsNoRecording={nextIsNoRecording}
               segmentDuration={segmentDuration}
@@ -216,6 +220,7 @@ export const VirtualizedMotionSegments = forwardRef<
         events,
         getMotionSegmentValue,
         getRecordingAvailability,
+        getIsSubOnly,
         motionOnly,
         segmentDuration,
         showMinimap,

web/src/hooks/use-draggable-element.ts

@@ -1,4 +1,5 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { isIOS } from "react-device-detect";
 import { useTimelineUtils } from "./use-timeline-utils";
 import { FrigateConfig } from "@/types/frigateConfig";
 import useSWR from "swr";
@@ -10,6 +11,11 @@ import useUserInteraction from "./use-user-interaction";
 
 const DRAG_STATE_COMMIT_MS = 100;
 
+// iOS Safari synthesizes a click shortly after a drag's touchend even
+// though the touchend handler calls preventDefault; clicks observed in
+// traces arrive ~50ms after release
+const GHOST_CLICK_WINDOW_MS = 400;
+
 type DraggableElementProps = {
   contentRef: React.RefObject<HTMLElement | null>;
   timelineRef: React.RefObject<HTMLDivElement | null>;
@@ -164,9 +170,28 @@ function useDraggableElement({
           setDraggableElementTime(pendingDragTimeRef.current);
           pendingDragTimeRef.current = null;
         }
+
+        // iOS Safari synthesizes a click after touchend despite the
+        // preventDefault, hit-tested at the drag origin where a segment
+        // now sits; its onClick would yank the handlebar back
+        if (isIOS && "TouchEvent" in window && e instanceof TouchEvent) {
+          const swallow = (clickEvent: MouseEvent) => {
+            cleanup();
+            if (timelineRef.current?.contains(clickEvent.target as Node)) {
+              clickEvent.preventDefault();
+              clickEvent.stopPropagation();
+            }
+          };
+          const cleanup = () => {
+            document.removeEventListener("click", swallow, true);
+            window.clearTimeout(timer);
+          };
+          const timer = window.setTimeout(cleanup, GHOST_CLICK_WINDOW_MS);
+          document.addEventListener("click", swallow, true);
+        }
       }
     },
-    [isDragging, setIsDragging, setDraggableElementTime],
+    [isDragging, setIsDragging, setDraggableElementTime, timelineRef],
   );
 
   const timestampToPixels = useCallback(

web/src/types/cameraWizard.ts

@@ -75,7 +75,7 @@ export const CAMERA_BRAND_VALUES = CAMERA_BRANDS.map(
 
 export type CameraBrand = (typeof CAMERA_BRANDS)[number]["value"];
 
-export type StreamRole = "detect" | "record" | "audio";
+export type StreamRole = "detect" | "record" | "record_sub" | "audio";
 
 export type StreamConfig = {
   id: string;

web/src/types/filter.ts

@@ -11,6 +11,25 @@ export type FilterList = {
 
 export const LAST_24_HOURS_KEY = "last24Hours";
 
+const DRAWER_FEATURES = [
+  "export",
+  "calendar",
+  "filter",
+  "debug-replay",
+  "share-timestamp",
+  "motion-search",
+  "quality",
+] as const;
+export type DrawerFeatures = (typeof DRAWER_FEATURES)[number];
+export const DEFAULT_DRAWER_FEATURES: DrawerFeatures[] = [
+  "export",
+  "calendar",
+  "filter",
+  "debug-replay",
+  "share-timestamp",
+  "motion-search",
+];
+
 export type GeneralFilter = {
   showAll?: boolean;
   labels?: string[];

web/src/types/frigateConfig.ts

@@ -96,6 +96,7 @@ export interface CameraConfig {
     output_args: {
       detect: string[];
       record: string;
+      record_sub: string | string[];
       rtmp: string;
     };
     retry_interval: number;
@@ -235,6 +236,9 @@ export interface CameraConfig {
       days: number;
       mode: string;
     };
+    sub: {
+      enabled: boolean;
+    };
   };
   review: {
     alerts: {
@@ -492,6 +496,7 @@ export interface FrigateConfig {
     output_args: {
       detect: string[];
       record: string;
+      record_sub: string | string[];
       rtmp: string;
     };
     retry_interval: number;

web/src/types/record.ts

@@ -45,6 +45,48 @@ export type RecordingStartingPoint = {
 
 export type RecordingPlayerError = "stalled" | "startup";
 
+export type RecordingCoverageSpan = {
+  start_time: number;
+  end_time: number;
+  streams: ("main" | "sub")[];
+};
+
+export type StreamMediaSummary = {
+  video_codec: string | null;
+  audio_rate: number | null;
+  audio_codec: string | null;
+  has_audio: boolean | null;
+  bitrate: number | null;
+};
+
+// why auto quality is currently resolved to the low stream
+export type AutoQualityReason = "bandwidth" | "codec" | "saveData";
+
+// one span of a vod route's realized playlist. duration is in ms and
+// exceeds the wall length when the clip carries keyframe back-snap
+// lead-in; 0 means the clip is omitted from the playlist entirely
+export type PlaybackTimelineSpan = {
+  start_time: number;
+  end_time: number;
+  duration: number;
+};
+
+export type RecordingCoverage = {
+  spans: RecordingCoverageSpan[];
+  // informational, kept for API consumers; the UI no longer gates on it
+  codecs_compatible: boolean;
+  streams: { main?: StreamMediaSummary; sub?: StreamMediaSummary };
+  // opt-in (?timelines=true); absent on requests that skip them
+  timelines?: {
+    auto: PlaybackTimelineSpan[];
+    main: PlaybackTimelineSpan[];
+    sub: PlaybackTimelineSpan[];
+  };
+};
+
+export type PlaybackQuality = "auto" | "main" | "sub";
+export const PLAYBACK_QUALITIES: PlaybackQuality[] = ["auto", "main", "sub"];
+
 export const ASPECT_VERTICAL_LAYOUT = 1.5;
 export const ASPECT_PORTRAIT_LAYOUT = 1.333;
 export const ASPECT_WIDE_LAYOUT = 2;

web/src/utils/codecSupport.ts

@@ -0,0 +1,73 @@
+/**
+ * Best-effort probe for whether this browser can decode a video codec
+ * family.
+ *
+ * Frigate only stores the codec family from ffprobe (no profile or
+ * level), so the probe tests representative MIME samples per family.
+ * The result is a hint, not proof: a 10-bit stream can fail on a
+ * browser that passes the Main-profile sample, so callers must keep a
+ * reactive fallback for fatal codec errors. Unknown or NULL codecs
+ * (legacy rows) always report supported - a wrong "unsupported" answer
+ * silently degrades quality, which is worse than a failed attempt the
+ * reactive path recovers from.
+ */
+
+declare global {
+  interface Window {
+    ManagedMediaSource?: typeof MediaSource;
+  }
+}
+
+// any one supported sample marks the family playable
+const CODEC_MIME_SAMPLES: Record<string, string[]> = {
+  h264: ['video/mp4; codecs="avc1.42E01E"', 'video/mp4; codecs="avc1.64001F"'],
+  hevc: [
+    'video/mp4; codecs="hvc1.1.6.L120.90"',
+    'video/mp4; codecs="hev1.1.6.L120.90"',
+  ],
+  av1: ['video/mp4; codecs="av01.0.05M.08"'],
+};
+
+const FAMILY_ALIASES: Record<string, string> = {
+  avc: "h264",
+  avc1: "h264",
+  h265: "hevc",
+  hev1: "hevc",
+  hvc1: "hevc",
+  av01: "av1",
+};
+
+function canPlayMimeType(mimeType: string): boolean {
+  if (window.ManagedMediaSource?.isTypeSupported(mimeType)) {
+    return true;
+  }
+
+  if (window.MediaSource?.isTypeSupported(mimeType)) {
+    return true;
+  }
+
+  // native playback fallback for browsers without MSE
+  return document.createElement("video").canPlayType(mimeType) !== "";
+}
+
+/**
+ * Fails open: unknown codecs and NULL (legacy) codecs report supported,
+ * since wrongly downgrading quality is worse than a recoverable failure.
+ */
+export function isCodecFamilySupported(
+  codecName: string | null | undefined,
+): boolean {
+  if (!codecName) {
+    return true;
+  }
+
+  const normalized = codecName.toLowerCase().trim();
+  const family = FAMILY_ALIASES[normalized] ?? normalized;
+  const samples = CODEC_MIME_SAMPLES[family];
+
+  if (!samples) {
+    return true;
+  }
+
+  return samples.some(canPlayMimeType);
+}

web/src/utils/videoUtil.ts

@@ -61,15 +61,18 @@ export function calculateSeekPosition(
       return false;
     }
 
+    // playlist duration exceeds wall length when the clip carries
+    // keyframe back-snap lead-in
+    const wallLength = segment.end_time - segment.start_time;
+    const leadIn = Math.max(0, segment.duration - wallLength);
+
     if (segment.end_time < timestamp) {
-      // Add the full duration of this segment
-      seekSeconds += segment.end_time - segment.start_time;
+      seekSeconds += segment.duration;
       return true;
     }
 
     // We're in this segment - calculate position within it
-    seekSeconds +=
-      segment.end_time - segment.start_time - (segment.end_time - timestamp);
+    seekSeconds += leadIn + (timestamp - segment.start_time);
     return true;
   });
 

web/src/views/motion-search/MotionSearchView.tsx

@@ -615,16 +615,16 @@ export default function MotionSearchView({
   }, [selectedRangeIdx, chunkedTimeRange]);
 
   const updateSelectedSegment = useCallback(
-    (nextTime: number, updateStartTime: boolean) => {
+    (nextTime: number) => {
       const index = chunkedTimeRange.findIndex(
         (segment) => segment.after <= nextTime && segment.before >= nextTime,
       );
 
       if (index != -1) {
-        if (updateStartTime) {
-          setPlaybackStart(nextTime);
-        }
-
+        setPlaybackStart(nextTime);
+        // the outgoing chunk's player runs until the new source replaces
+        // it, reporting old positions while the new chunk loads
+        mainControllerRef.current?.pause();
         setSelectedRangeIdx(index);
       }
     },
@@ -638,7 +638,10 @@ export default function MotionSearchView({
         currentTime > currentTimeRange.before + 60 ||
         currentTime < currentTimeRange.after - 60
       ) {
-        updateSelectedSegment(currentTime, false);
+        // the player rebuilds its source against playbackStart, and a
+        // stale anchor resolves to no startPosition, dropping playback
+        // at the start of the hour instead of the drag target
+        updateSelectedSegment(currentTime);
         return;
       }
 
@@ -678,9 +681,12 @@ export default function MotionSearchView({
           currentTimeRange.after <= currentTime &&
           currentTimeRange.before >= currentTime
         ) {
+          // a source reload mid-seek resumes from playbackStart, so the
+          // anchor has to follow explicit seeks
+          setPlaybackStart(currentTime);
           mainControllerRef.current?.seekToTimestamp(currentTime, true);
         } else {
-          updateSelectedSegment(currentTime, true);
+          updateSelectedSegment(currentTime);
         }
       } else if (playerTime != currentTime) {
         mainControllerRef.current?.play();
@@ -700,9 +706,12 @@ export default function MotionSearchView({
       setCurrentTime(time);
 
       if (currentTimeRange.after <= time && currentTimeRange.before >= time) {
+        // a source reload mid-seek resumes from playbackStart, so the
+        // anchor has to follow explicit seeks
+        setPlaybackStart(time);
         mainControllerRef.current?.seekToTimestamp(time, play);
       } else {
-        updateSelectedSegment(time, true);
+        updateSelectedSegment(time);
       }
     },
     [currentTimeRange, updateSelectedSegment],

web/src/views/recording/RecordingView.tsx

@@ -8,13 +8,15 @@ import PreviewPlayer, {
 } from "@/components/player/PreviewPlayer";
 import { DynamicVideoController } from "@/components/player/dynamic/DynamicVideoController";
 import DynamicVideoPlayer from "@/components/player/dynamic/DynamicVideoPlayer";
+import QualitySelector from "@/components/player/QualitySelector";
 import MotionReviewTimeline from "@/components/timeline/MotionReviewTimeline";
 import DetailStream from "@/components/timeline/DetailStream";
 import { Button } from "@/components/ui/button";
 import { ToggleGroup, ToggleGroupItem } from "@/components/ui/toggle-group";
 import { useOverlayState } from "@/hooks/use-overlay-state";
+import { usePersistence } from "@/hooks/use-persistence";
 import { useResizeObserver } from "@/hooks/resize-observer";
-import { ExportMode } from "@/types/filter";
+import { DEFAULT_DRAWER_FEATURES, ExportMode } from "@/types/filter";
 import { FrigateConfig } from "@/types/frigateConfig";
 import { Preview } from "@/types/preview";
 import {
@@ -57,9 +59,13 @@ import { VideoResolutionType } from "@/types/live";
 import {
   ASPECT_VERTICAL_LAYOUT,
   ASPECT_WIDE_LAYOUT,
+  AutoQualityReason,
+  PlaybackQuality,
+  RecordingCoverage,
   RecordingSegment,
   RecordingStartingPoint,
 } from "@/types/record";
+import { isCodecFamilySupported } from "@/utils/codecSupport";
 import { cn } from "@/lib/utils";
 import { useFullscreen } from "@/hooks/use-fullscreen";
 import { useTimezone } from "@/hooks/use-date-utils";
@@ -141,6 +147,15 @@ export function RecordingView({
     },
   ]);
 
+  // feeds the quality selector's per-stream subtitles
+  const { data: coverage } = useSWR<RecordingCoverage>([
+    `${mainCamera}/recordings/coverage`,
+    {
+      before: timeRange.before,
+      after: timeRange.after,
+    },
+  ]);
+
   // controller state
 
   const mainControllerRef = useRef<DynamicVideoController | null>(null);
@@ -280,14 +295,14 @@ export function RecordingView({
   const [playerTime, setPlayerTime] = useState(startTime);
 
   const updateSelectedSegment = useCallback(
-    (currentTime: number, updateStartTime: boolean) => {
+    (currentTime: number) => {
       const index = findChunkIndex(chunkedTimeRange, currentTime);
 
       if (index != -1) {
-        if (updateStartTime) {
-          setPlaybackStart(currentTime);
-        }
-
+        setPlaybackStart(currentTime);
+        // the outgoing chunk's player runs until the new source replaces
+        // it, reporting old positions while the new chunk loads
+        mainControllerRef.current?.pause();
         setSelectedRangeIdx(index);
       }
     },
@@ -300,7 +315,10 @@ export function RecordingView({
         currentTime > currentTimeRange.before + 60 ||
         currentTime < currentTimeRange.after - 60
       ) {
-        updateSelectedSegment(currentTime, false);
+        // the player rebuilds its source against playbackStart, and a
+        // stale anchor resolves to no startPosition, dropping playback
+        // at the start of the hour instead of the drag target
+        updateSelectedSegment(currentTime);
         return;
       }
 
@@ -328,9 +346,12 @@ export function RecordingView({
       setCurrentTime(time);
 
       if (currentTimeRange.after <= time && currentTimeRange.before >= time) {
+        // a source reload mid-seek resumes from playbackStart, so the
+        // anchor has to follow explicit seeks
+        setPlaybackStart(time);
         mainControllerRef.current?.seekToTimestamp(time, play);
       } else {
-        updateSelectedSegment(time, true);
+        updateSelectedSegment(time);
       }
     },
     [currentTimeRange, updateSelectedSegment],
@@ -388,13 +409,15 @@ export function RecordingView({
               shouldPlayback = mainControllerRef.current.isPlaying();
             }
 
+            // see manuallySetCurrentTime
+            setPlaybackStart(currentTime);
             mainControllerRef.current.seekToTimestamp(
               currentTime,
               shouldPlayback,
             );
           }
         } else {
-          updateSelectedSegment(currentTime, true);
+          updateSelectedSegment(currentTime);
         }
       } else if (playerTime != currentTime && timelineType != "detail") {
         mainControllerRef.current?.play();
@@ -409,6 +432,58 @@ export function RecordingView({
     height: 0,
   });
 
+  // playback quality
+
+  const [quality, setQuality] = usePersistence<PlaybackQuality>(
+    "recordingQuality",
+    "auto",
+  );
+
+  // lets the selector surface a downswitch instead of a mysterious drop
+  const [autoQualityLow, setAutoQualityLow] = useState<{
+    low: boolean;
+    reason?: AutoQualityReason;
+  }>({ low: false });
+
+  // the player re-notifies on every mount and quality reset, so keep the
+  // same state object when nothing changed
+  const onAutoQualityChange = useCallback(
+    (low: boolean, reason: AutoQualityReason | undefined) =>
+      setAutoQualityLow((prev) =>
+        prev.low === low && prev.reason === reason ? prev : { low, reason },
+      ),
+    [],
+  );
+
+  // shown on the Original pin so a doomed selection is labeled
+  const mainCodecUnsupported = useMemo(
+    () =>
+      coverage?.streams?.main
+        ? !isCodecFamilySupported(coverage.streams.main.video_codec)
+        : false,
+    [coverage],
+  );
+
+  // the pin is persisted globally, but the selector is hidden on cameras
+  // without a sub stream, leaving an inherited "sub" pin unable to unpin
+  const playerQuality = useMemo<PlaybackQuality | undefined>(
+    () =>
+      config && !config.cameras[mainCamera]?.record.sub.enabled
+        ? "auto"
+        : quality,
+    [config, mainCamera, quality],
+  );
+
+  // a quality change swaps the playlist source, so anchor playback start
+  // the same way camera switching does to resume in place
+  const onSetQuality = useCallback(
+    (newQuality: PlaybackQuality) => {
+      setPlaybackStart(currentTime);
+      setQuality(newQuality);
+    },
+    [currentTime, setQuality],
+  );
+
   const onSelectCamera = useCallback(
     (newCam: string) => {
       if (allowedCameras.includes(newCam)) {
@@ -768,6 +843,18 @@ export function RecordingView({
                 }}
               />
             )}
+            {!isMobileOnly &&
+              config?.cameras[mainCamera]?.record.enabled &&
+              config?.cameras[mainCamera]?.record.sub.enabled && (
+                <QualitySelector
+                  quality={quality ?? "auto"}
+                  onSetQuality={onSetQuality}
+                  streams={coverage?.streams}
+                  autoLow={(quality ?? "auto") === "auto" && autoQualityLow.low}
+                  autoLowReason={autoQualityLow.reason}
+                  mainUnsupported={mainCodecUnsupported}
+                />
+              )}
             {isDesktop ? (
               <ToggleGroup
                 className="*:rounded-md *:px-3 *:py-4"
@@ -807,6 +894,23 @@ export function RecordingView({
               />
             )}
             <MobileReviewSettingsDrawer
+              // tablets keep the header selector, so only phones get
+              // quality in the drawer
+              features={
+                isMobileOnly &&
+                config?.cameras[mainCamera]?.record.enabled &&
+                config?.cameras[mainCamera]?.record.sub.enabled
+                  ? [...DEFAULT_DRAWER_FEATURES, "quality"]
+                  : DEFAULT_DRAWER_FEATURES
+              }
+              quality={quality ?? "auto"}
+              onSetQuality={onSetQuality}
+              qualityStreams={coverage?.streams}
+              qualityAutoLow={
+                (quality ?? "auto") === "auto" && autoQualityLow.low
+              }
+              qualityAutoLowReason={autoQualityLow.reason}
+              qualityMainUnsupported={mainCodecUnsupported}
               camera={mainCamera}
               filter={filter}
               currentTime={currentTime}
@@ -929,6 +1033,8 @@ export function RecordingView({
                   setFullResolution={setFullResolution}
                   toggleFullscreen={toggleFullscreen}
                   containerRef={mainLayoutRef}
+                  quality={playerQuality}
+                  onAutoQualityChange={onAutoQualityChange}
                 />
               </div>
               {isDesktop && effectiveCameras.length > 1 && (
@@ -1131,6 +1237,20 @@ function Timeline({
     },
   ]);
 
+  const { data: coverage } = useSWR<RecordingCoverage>([
+    `${mainCamera}/recordings/coverage`,
+    {
+      before: alignedBefore,
+      after: alignedAfter,
+    },
+  ]);
+
+  const subOnlyRanges = useMemo(
+    () =>
+      coverage?.spans?.filter((span) => !span.streams.includes("main")) ?? [],
+    [coverage],
+  );
+
   const [exportStart, setExportStartTime] = useState<number>(0);
   const [exportEnd, setExportEndTime] = useState<number>(0);
 
@@ -1200,6 +1320,7 @@ function Timeline({
             events={mainCameraReviewItems}
             motion_events={motionData ?? []}
             noRecordingRanges={noRecordings ?? []}
+            subOnlyRanges={subOnlyRanges}
             contentRef={contentRef}
             onHandlebarDraggingChange={setScrubbing}
             isZooming={isZooming}