Video freeze and segment repeat after starting a short HLS event playlist

spirgiuz commented 1 year ago

Media3 Version

ExoPlayer 2.18.6

Devices that reproduce the issue

Xiaomi MiTV running AndroidTV 9 Emulator running any AndroidTV 8 Emulator running Android 11 Sony Bravia VH21 running AndroidTV 10

Devices that do not reproduce the issue

So far all devices tested reproduce the issue.

Reproducible in the demo app?

Yes

Reproduction steps

Start playing an HLS event playlist that has not ended yet and is under a minute long
Play for 30-40 seconds

Expected result

The media plays without any freezes or audio loops.

Actual result

The video freezes, sound loops back to an already played segment. When audio catches up to video, playback normalizes. The logs show a AudioSink$UnexpectedDiscontinuityException:

Audio sink error
com.google.android.exoplayer2.audio.AudioSink$UnexpectedDiscontinuityException: Unexpected audio track timestamp discontinuity: expected 1000033816011, got 1000025816000
at com.google.android.exoplayer2.audio.DefaultAudioSink.handleBuffer(DefaultAudioSink.java:999)
atc om.google.android.exoplayer2.audio.MediaCodecAudioRenderer.processOutputBuffer(MediaCodecAudioRenderer.java:709)
at com.google.android.exoplayer2.mediacodec.MediaCodecRenderer.drainOutputBuffer(MediaCodecRenderer.java:1889)
at com.google.android.exoplayer2.mediacodec.MediaCodecRenderer.render(MediaCodecRenderer.java:782)
at com.google.android.exoplayer2.ExoPlayerImplInternal.doSomeWork(ExoPlayerImplInternal.java:1007)
at com.google.android.exoplayer2.ExoPlayerImplInternal.handleMessage(ExoPlayerImplInternal.java:502)
at android.os.Handler.dispatchMessage(Handler.java:101)
at android.os.Looper.loop(Looper.java:164)
at android.os.HandlerThread.run(HandlerThread.java:65)

and some frame drops: droppedFrames [eventTime=34.04, mediaPos=43.76, window=0, period=0, 167]

On Sony Bravia VH21, after the bug audio/video desync appears.

Playing the same URL after a few minutes, when the event stream is longer than a minute does not reproduce this error anymore.

This issue is not new, it has been present since at least r2.15.1 but probably even earlier.

Media

I will provide URL of a stream that this happens on by email, though it doesn't seem to depend on the stream and happens as long as it's an HLS event stream shorter than a minute.

Bug Report

[ ] You will email the zip file produced by adb bugreport to dev.exoplayer@gmail.com after filing this issue.

spirgiuz commented 1 year ago

@tianyif sorry to bother you, have you had the chance to look at this?

spirgiuz commented 10 months ago

After some debugging I've found that the server adds an additional segment to the start of the playlist when adding the 5th segment. That moves all the existing segments over by 1 and probably explains why the audio discontinuity is about 8 seconds (our target segment size). I'm guessing this is likely not ExoPlayer's problem, because as I recall according to HLS spec, you can only add segments at the end in event playlists.

androidx / media