Handle when RTSP track timing is not available.

Issue: google/ExoPlayer#9775

We got a few issues for this on GH already. Some RTSP servers do not provide
track timing in PLAY responses, or the timings are invalid.

Missing timing means the RTSP stream is not seekable. Added method to
1. Update the timeline that seek is not possible
2. Report read discontinuity so that playback can start from the beginning.

PiperOrigin-RevId: 423281439

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/RtspMediaPeriod.java

@@ -69,6 +69,9 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
     /** Called when the {@link RtspSessionTiming} is available. */
     void onSourceInfoRefreshed(RtspSessionTiming timing);
+
+    /** Called when the RTSP server does not support seeking. */
+    default void onSeekingUnsupported() {}
   }
 
   /** The maximum times to retry if the underlying data channel failed to bind. */
@@ -92,6 +95,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   private long pendingSeekPositionUs;
   private long pendingSeekPositionUsForTcpRetry;
   private boolean loadingFinished;
+  private boolean notifyDiscontinuity;
   private boolean released;
   private boolean prepared;
   private boolean trackSelected;
@@ -245,6 +249,14 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
   @Override
   public long readDiscontinuity() {
+    // Discontinuity only happens in RTSP when seeking an unexpectedly un-seekable RTSP server (a
+    // server that doesn't include the required RTP-Info header in its PLAY responses). This only
+    // applies to seeks made before receiving the first RTSP PLAY response. The playback can only
+    // start from time zero in this case.
+    if (notifyDiscontinuity) {
+      notifyDiscontinuity = false;
+      return 0;
+    }
     return C.TIME_UNSET;
   }
 
@@ -357,7 +369,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   // SampleStream methods.
 
   /* package */ boolean isReady(int trackGroupIndex) {
-    return rtspLoaderWrappers.get(trackGroupIndex).isSampleQueueReady();
+    return !suppressRead() && rtspLoaderWrappers.get(trackGroupIndex).isSampleQueueReady();
   }
 
   @ReadDataResult
@@ -366,9 +378,23 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       FormatHolder formatHolder,
       DecoderInputBuffer buffer,
       @ReadFlags int readFlags) {
+    if (suppressRead()) {
+      return C.RESULT_NOTHING_READ;
+    }
     return rtspLoaderWrappers.get(sampleQueueIndex).read(formatHolder, buffer, readFlags);
   }
 
+  /* package */ int skipData(int sampleQueueIndex, long positionUs) {
+    if (suppressRead()) {
+      return C.RESULT_NOTHING_READ;
+    }
+    return rtspLoaderWrappers.get(sampleQueueIndex).skipData(positionUs);
+  }
+
+  private boolean suppressRead() {
+    return notifyDiscontinuity;
+  }
+
   // Internal methods.
 
   @Nullable
@@ -551,7 +577,9 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     @Override
     public void onPlaybackStarted(
         long startPositionUs, ImmutableList<RtspTrackTiming> trackTimingList) {
-      // Validate that the trackTimingList contains timings for the selected tracks.
+
+      // Validate that the trackTimingList contains timings for the selected tracks, and notify the
+      // listener.
       ArrayList<String> trackUrisWithTiming = new ArrayList<>(trackTimingList.size());
       for (int i = 0; i < trackTimingList.size(); i++) {
         trackUrisWithTiming.add(checkNotNull(trackTimingList.get(i).uri.getPath()));
@@ -559,10 +587,13 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       for (int i = 0; i < selectedLoadInfos.size(); i++) {
         RtpLoadInfo loadInfo = selectedLoadInfos.get(i);
         if (!trackUrisWithTiming.contains(loadInfo.getTrackUri().getPath())) {
-          playbackException =
-              new RtspPlaybackException(
-                  "Server did not provide timing for track " + loadInfo.getTrackUri());
-          return;
+          listener.onSeekingUnsupported();
+          if (isSeekPending()) {
+            notifyDiscontinuity = true;
+            pendingSeekPositionUs = C.TIME_UNSET;
+            requestedSeekPositionUs = C.TIME_UNSET;
+            pendingSeekPositionUsForTcpRetry = C.TIME_UNSET;
+          }
         }
       }
 
@@ -699,7 +730,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
     @Override
     public int skipData(long positionUs) {
-      return 0;
+      return RtspMediaPeriod.this.skipData(track, positionUs);
     }
   }
 
@@ -750,6 +781,12 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       return sampleQueue.read(formatHolder, buffer, readFlags, /* loadingFinished= */ canceled);
     }
 
+    public int skipData(long positionUs) {
+      int skipCount = sampleQueue.getSkipCount(positionUs, /* allowEndOfQueue= */ canceled);
+      sampleQueue.skip(skipCount);
+      return skipCount;
+    }
+
     /** Cancels loading. */
     public void cancelLoad() {
       if (!canceled) {

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/RtspMediaSource.java

@@ -257,12 +257,21 @@ public final class RtspMediaSource extends BaseMediaSource {
         allocator,
         rtpDataChannelFactory,
         uri,
-        /* listener= */ timing -> {
+        new RtspMediaPeriod.Listener() {
+          @Override
+          public void onSourceInfoRefreshed(RtspSessionTiming timing) {
             timelineDurationUs = Util.msToUs(timing.getDurationMs());
             timelineIsSeekable = !timing.isLive();
             timelineIsLive = timing.isLive();
             timelineIsPlaceholder = false;
             notifySourceInfoRefreshed();
+          }
+
+          @Override
+          public void onSeekingUnsupported() {
+            timelineIsSeekable = false;
+            notifySourceInfoRefreshed();
+          }
         },
         userAgent,
         socketFactory,