Fix preview players at the hour rollover (#24157)

* fix preview players at the hour rollover

* clean up

web/src/components/player/PreviewPlayer.tsx

@@ -10,7 +10,7 @@ import useSWR from "swr";
 import { FrigateConfig } from "@/types/frigateConfig";
 import { Preview } from "@/types/preview";
 import { PreviewPlayback } from "@/types/playback";
-import { isCurrentHour } from "@/utils/dateUtil";
+import { isCurrentOrPreviousHour } from "@/utils/dateUtil";
 import { baseUrl } from "@/api/baseUrl";
 import { isAndroid, isChrome, isMobile } from "react-device-detect";
 import { TimeRange } from "@/types/timeline";
@@ -76,7 +76,7 @@ export default function PreviewPlayer({
     );
   }
 
-  if (isCurrentHour(timeRange.before)) {
+  if (isCurrentOrPreviousHour(timeRange.before)) {
     return (
       <PreviewFramesPlayer
         className={className}
@@ -345,7 +345,7 @@ function PreviewVideoPlayer({
       )}
       {cameraPreviews && !currentPreview && (
         <div className="absolute inset-0 flex items-center justify-center rounded-lg bg-background_alt text-primary dark:bg-black md:rounded-2xl">
-          {t("noPreviewFoundFor", { camera: cameraName })}
+          {t("noPreviewFoundFor", { cameraName: cameraName })}
         </div>
       )}
       {firstLoad && <Skeleton className="absolute aspect-video size-full" />}

web/src/components/player/PreviewThumbnailPlayer.tsx

@@ -1,6 +1,6 @@
 import React, { useCallback, useEffect, useMemo, useState } from "react";
 import { useApiHost } from "@/api";
-import { isCurrentHour } from "@/utils/dateUtil";
+import { isCurrentOrPreviousHour } from "@/utils/dateUtil";
 import {
   ReviewSegment,
   ThreatLevel,
@@ -139,9 +139,19 @@ export default function PreviewThumbnailPlayer({
   const [hoverTimeout, setHoverTimeout] = useState<NodeJS.Timeout | null>();
   const [playback, setPlayback] = useState(false);
   const [tooltipHovering, setTooltipHovering] = useState(false);
+
+  const thumbnailUrl = `${apiHost}${review.thumb_path.replace("/media/frigate/", "")}`;
+
+  // not memoized: depends on the wall clock, and a stale value blanks the card
+  // for a whole hour after a rollover
+  const hasPreviewContent =
+    relevantPreview != undefined || isCurrentOrPreviousHour(review.start_time);
+
+  // playback hides the thumbnail below, and only a mounted player calls
+  // isPlayingBack(false), so entering it empty leaves the card black
   const playingBack = useMemo(
-    () => playback && !tooltipHovering,
-    [playback, tooltipHovering],
+    () => playback && !tooltipHovering && hasPreviewContent,
+    [playback, tooltipHovering, hasPreviewContent],
   );
   const [isHovered, setIsHovered] = useState(false);
 
@@ -208,6 +218,7 @@ export default function PreviewThumbnailPlayer({
             review={review}
             relevantPreview={relevantPreview}
             timeRange={timeRange}
+            defaultImageUrl={thumbnailUrl}
             setReviewed={handleSetReviewed}
             setIgnoreClick={setIgnoreClick}
             isPlayingBack={setPlayback}
@@ -234,7 +245,7 @@ export default function PreviewThumbnailPlayer({
               : undefined
           }
           draggable={false}
-          src={`${apiHost}${review.thumb_path.replace("/media/frigate/", "")}`}
+          src={thumbnailUrl}
           loading={isSafari ? "eager" : "lazy"}
           onLoad={() => {
             onImgLoad();
@@ -394,6 +405,7 @@ type PreviewContentProps = {
   review: ReviewSegment;
   relevantPreview: Preview | undefined;
   timeRange: TimeRange;
+  defaultImageUrl: string;
   setReviewed: () => void;
   setIgnoreClick: (ignore: boolean) => void;
   isPlayingBack: (ended: boolean) => void;
@@ -403,6 +415,7 @@ function PreviewContent({
   review,
   relevantPreview,
   timeRange,
+  defaultImageUrl,
   setReviewed,
   setIgnoreClick,
   isPlayingBack,
@@ -423,13 +436,14 @@ function PreviewContent({
         windowVisible={true}
       />
     );
-  } else if (isCurrentHour(review.start_time)) {
+  } else if (isCurrentOrPreviousHour(review.start_time)) {
     return (
       <InProgressPreview
         camera={review.camera}
         startTime={review.start_time}
         endTime={review.end_time}
         timeRange={timeRange}
+        defaultImageUrl={defaultImageUrl}
         setReviewed={setReviewed}
         setIgnoreClick={setIgnoreClick}
         isPlayingBack={isPlayingBack}
@@ -438,4 +452,7 @@ function PreviewContent({
       />
     );
   }
+
+  // unreachable while the caller gates on hasPreviewContent
+  return <img className="size-full" src={defaultImageUrl} />;
 }

web/src/hooks/use-camera-previews.ts

@@ -2,11 +2,13 @@ import { Preview } from "@/types/preview";
 import { TimeRange } from "@/types/timeline";
 import { useEffect, useMemo, useState } from "react";
 import useSWR from "swr";
+import { useHourRollover } from "@/hooks/use-hour-rollover";
 
 type OptionalCameraPreviewProps = {
   camera?: string;
   autoRefresh?: boolean;
   fetchPreviews?: boolean;
+  refreshOnHourRollover?: boolean;
 };
 export function useCameraPreviews(
   initialTimeRange: TimeRange,
@@ -14,6 +16,7 @@ export function useCameraPreviews(
     camera = "all",
     autoRefresh = true,
     fetchPreviews = true,
+    refreshOnHourRollover = false,
   }: OptionalCameraPreviewProps,
 ) {
   const [timeRange, setTimeRange] = useState(initialTimeRange);
@@ -22,33 +25,52 @@ export function useCameraPreviews(
     setTimeRange(initialTimeRange);
   }, [initialTimeRange]);
 
-  const { data: allPreviews } = useSWR<Preview[]>(
+  const { data: allPreviews, mutate: refreshPreviews } = useSWR<Preview[]>(
     fetchPreviews
       ? `preview/${camera}/start/${Math.round(timeRange.after)}/end/${Math.round(timeRange.before)}`
       : null,
     { revalidateOnFocus: autoRefresh, revalidateOnReconnect: autoRefresh },
   );
 
+  // an hour's mp4 is written after that hour ends, so it is never in the
+  // response the page loaded with
+  useHourRollover(refreshPreviews, refreshOnHourRollover && fetchPreviews);
+
   return fetchPreviews ? allPreviews : [];
 }
 
-// we need to add a buffer of 5 seconds to the end preview times
-// this ensures that if preview generation is running slowly
-// and the previews are generated 1-5 seconds late
-// it is not falsely thrown out.
-const PREVIEW_END_BUFFER = 5; // seconds
-
 export function getPreviewForTimeRange(
   allPreviews: Preview[],
   camera: string,
   timeRange: TimeRange,
 ) {
-  return allPreviews.find(
-    (preview) =>
-      preview.camera == camera &&
-      Math.ceil(preview.start) >= timeRange.after &&
-      Math.floor(preview.end) <= timeRange.before + PREVIEW_END_BUFFER,
-  );
+  let best: Preview | undefined = undefined;
+  let bestOverlap = 0;
+
+  for (const preview of allPreviews) {
+    // a preview belongs to the hour it starts in. a camera whose feed drops
+    // across the boundary produces one ending minutes into the next hour, and
+    // without this it would claim that hour's slot as well.
+    if (
+      preview.camera != camera ||
+      Math.ceil(preview.start) < timeRange.after
+    ) {
+      continue;
+    }
+
+    // the slot for the live hour is stamped at page load and never grows, so
+    // an hour-long preview never fits inside it. rank by overlap instead.
+    const overlap =
+      Math.min(preview.end, timeRange.before) -
+      Math.max(preview.start, timeRange.after);
+
+    if (overlap > bestOverlap) {
+      bestOverlap = overlap;
+      best = preview;
+    }
+  }
+
+  return best;
 }
 
 export function usePreviewForTimeRange(

web/src/hooks/use-hour-rollover.ts

@@ -0,0 +1,53 @@
+import { useEffect, useRef } from "react";
+
+// the mp4 lands some way past :00 (first frame after the boundary, then an
+// encode), and background tabs clamp timers to ~1min, so ladder rather than
+// fire once.
+const RETRY_OFFSETS = [15, 45, 120, 300]; // seconds past the hour
+
+/** Runs `callback` several times past each hour boundary; must be idempotent. */
+export function useHourRollover(callback: () => void, enabled: boolean = true) {
+  const callbackRef = useRef(callback);
+  callbackRef.current = callback;
+
+  useEffect(() => {
+    if (!enabled) {
+      return;
+    }
+
+    let timeouts: ReturnType<typeof setTimeout>[] = [];
+
+    const scheduleNextHour = () => {
+      // every prior timeout has fired by the time this reschedules itself
+      timeouts = [];
+
+      const now = Date.now();
+      const nextHour = new Date(now);
+      nextHour.setUTCMinutes(0, 0, 0);
+      nextHour.setUTCHours(nextHour.getUTCHours() + 1);
+      const msUntilBoundary = nextHour.getTime() - now;
+
+      RETRY_OFFSETS.forEach((offset) => {
+        timeouts.push(
+          setTimeout(
+            () => callbackRef.current(),
+            msUntilBoundary + offset * 1000,
+          ),
+        );
+      });
+
+      // repeat the ladder next hour
+      timeouts.push(
+        setTimeout(
+          scheduleNextHour,
+          msUntilBoundary +
+            (RETRY_OFFSETS[RETRY_OFFSETS.length - 1] + 1) * 1000,
+        ),
+      );
+    };
+
+    scheduleNextHour();
+
+    return () => timeouts.forEach(clearTimeout);
+  }, [enabled]);
+}

web/src/pages/Events.tsx

@@ -518,6 +518,7 @@ export default function Events() {
     previewTimes ?? { after: 0, before: 0 },
     {
       fetchPreviews: previewTimes != undefined,
+      refreshOnHourRollover: true,
     },
   );
 

web/src/utils/dateUtil.ts

@@ -385,6 +385,16 @@ export function isCurrentHour(timestamp: number) {
   return timestamp > now.getTime() / 1000;
 }
 
+// a just-ended hour has no mp4 yet but may still have cached frames, so it
+// stays eligible for the frame-based players
+export function isCurrentOrPreviousHour(timestamp: number) {
+  const previousHour = new Date();
+  previousHour.setUTCMinutes(0, 0, 0);
+  previousHour.setUTCHours(previousHour.getUTCHours() - 1);
+
+  return timestamp > previousHour.getTime() / 1000;
+}
+
 export const convertLocalDateToTimestamp = (dateString: string): number => {
   // Ensure the date string is in the correct format (8 digits)
   if (!/^\d{8}$/.test(dateString)) {

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

@@ -153,6 +153,7 @@ export default function MotionSearchView({
   const allPreviews = useCameraPreviews(timeRange, {
     camera: selectedCamera ?? undefined,
     fetchPreviews: !isSearchDialogOpen,
+    refreshOnHourRollover: true,
   });
 
   // ROI state