sync Tracking Details timeline with keyframe-snapped vod clip start (#22454)

web/src/components/overlay/detail/TrackingDetails.tsx

@@ -40,6 +40,7 @@ import ImageLoadingIndicator from "@/components/indicators/ImageLoadingIndicator
 import ObjectTrackOverlay from "../ObjectTrackOverlay";
 import { useIsAdmin } from "@/hooks/use-is-admin";
 import { VideoResolutionType } from "@/types/live";
+import { VodManifest } from "@/types/playback";
 
 type TrackingDetailsProps = {
   className?: string;
@@ -117,19 +118,64 @@ export function TrackingDetails({
     },
   );
 
+  // Fetch the VOD manifest JSON to get the actual clipFrom after keyframe
+  // snapping. The backend may snap clipFrom backwards to a keyframe, making
+  // the video start earlier than the requested time.
+  const vodManifestUrl = useMemo(() => {
+    if (!event.camera) return null;
+    const startTime =
+      event.start_time + annotationOffset / 1000 - REVIEW_PADDING;
+    const endTime =
+      (event.end_time ?? Date.now() / 1000) +
+      annotationOffset / 1000 +
+      REVIEW_PADDING;
+    return `vod/clip/${event.camera}/start/${startTime}/end/${endTime}`;
+  }, [event, annotationOffset]);
+
+  const { data: vodManifest } = useSWR<VodManifest>(vodManifestUrl, null, {
+    revalidateOnFocus: false,
+    revalidateOnReconnect: false,
+    dedupingInterval: 30000,
+  });
+
+  // Derive the actual video start time from the VOD manifest's first clip.
+  // Without this correction the timeline-to-player-time mapping is off by
+  // the keyframe preroll amount.
+  const actualVideoStart = useMemo(() => {
+    const videoStartTime = eventStartRecord - REVIEW_PADDING;
+
+    if (!vodManifest?.sequences?.[0]?.clips?.[0] || !recordings?.length) {
+      return videoStartTime;
+    }
+
+    const firstClip = vodManifest.sequences[0].clips[0];
+
+    // Guard: clipFrom is only expected when the first recording starts before
+    // the requested start. If this doesn't hold, fall back.
+    if (recordings[0].start_time >= videoStartTime) {
+      return recordings[0].start_time;
+    }
+
+    if (firstClip.clipFrom !== undefined) {
+      // clipFrom is in milliseconds from the start of the first recording
+      return recordings[0].start_time + firstClip.clipFrom / 1000;
+    }
+
+    // clipFrom absent means the full recording is included (keyframe probe failed)
+    return recordings[0].start_time;
+  }, [vodManifest, recordings, eventStartRecord]);
+
   // Convert a timeline timestamp to actual video player time, accounting for
   // motion-only recording gaps. Uses the same algorithm as DynamicVideoController.
   const timestampToVideoTime = useCallback(
     (timestamp: number): number => {
       if (!recordings || recordings.length === 0) {
         // Fallback to simple calculation if no recordings data
-        return timestamp - (eventStartRecord - REVIEW_PADDING);
+        return timestamp - actualVideoStart;
       }
 
-      const videoStartTime = eventStartRecord - REVIEW_PADDING;
-
-      // If timestamp is before video start, return 0
-      if (timestamp < videoStartTime) return 0;
+      // If timestamp is before actual video start, return 0
+      if (timestamp < actualVideoStart) return 0;
 
       // Check if timestamp is before the first recording or after the last
       if (
@@ -143,10 +189,10 @@ export function TrackingDetails({
       // Calculate the inpoint offset - the HLS video may start partway through the first segment
       let inpointOffset = 0;
       if (
-        videoStartTime > recordings[0].start_time &&
-        videoStartTime < recordings[0].end_time
+        actualVideoStart > recordings[0].start_time &&
+        actualVideoStart < recordings[0].end_time
       ) {
-        inpointOffset = videoStartTime - recordings[0].start_time;
+        inpointOffset = actualVideoStart - recordings[0].start_time;
       }
 
       let seekSeconds = 0;
@@ -164,7 +210,7 @@ export function TrackingDetails({
           if (segment === recordings[0]) {
             // For the first segment, account for the inpoint offset
             seekSeconds +=
-              timestamp - Math.max(segment.start_time, videoStartTime);
+              timestamp - Math.max(segment.start_time, actualVideoStart);
           } else {
             seekSeconds += timestamp - segment.start_time;
           }
@@ -174,7 +220,7 @@ export function TrackingDetails({
 
       return seekSeconds;
     },
-    [recordings, eventStartRecord],
+    [recordings, actualVideoStart],
   );
 
   // Convert video player time back to timeline timestamp, accounting for
@@ -183,19 +229,16 @@ export function TrackingDetails({
     (playerTime: number): number => {
       if (!recordings || recordings.length === 0) {
         // Fallback to simple calculation if no recordings data
-        const videoStartTime = eventStartRecord - REVIEW_PADDING;
-        return playerTime + videoStartTime;
+        return playerTime + actualVideoStart;
       }
 
-      const videoStartTime = eventStartRecord - REVIEW_PADDING;
-
       // Calculate the inpoint offset - the video may start partway through the first segment
       let inpointOffset = 0;
       if (
-        videoStartTime > recordings[0].start_time &&
-        videoStartTime < recordings[0].end_time
+        actualVideoStart > recordings[0].start_time &&
+        actualVideoStart < recordings[0].end_time
       ) {
-        inpointOffset = videoStartTime - recordings[0].start_time;
+        inpointOffset = actualVideoStart - recordings[0].start_time;
       }
 
       let timestamp = 0;
@@ -212,7 +255,7 @@ export function TrackingDetails({
           if (segment === recordings[0]) {
             // For the first segment, add the inpoint offset
             timestamp =
-              Math.max(segment.start_time, videoStartTime) +
+              Math.max(segment.start_time, actualVideoStart) +
               (playerTime - totalTime);
           } else {
             timestamp = segment.start_time + (playerTime - totalTime);
@@ -225,7 +268,7 @@ export function TrackingDetails({
 
       return timestamp;
     },
-    [recordings, eventStartRecord],
+    [recordings, actualVideoStart],
   );
 
   eventSequence?.map((event) => {

web/src/components/player/HlsVideoPlayer.tsx

@@ -352,7 +352,7 @@ export default function HlsVideoPlayer({
       >
         {isDetailMode &&
           camera &&
-          currentTime &&
+          currentTime != null &&
           loadedMetadata &&
           videoDimensions.width > 0 &&
           videoDimensions.height > 0 && (

web/src/types/playback.ts

@@ -11,3 +11,7 @@ export type PreviewPlayback = {
   preview: Preview | undefined;
   timeRange: TimeRange;
 };
+
+export type VodManifest = {
+  sequences: { clips: { clipFrom?: number }[] }[];
+};