Potential for Multiple Non-Internal Discontinuity Events

[skidder]

Version

Media3 1.1.1 / ExoPlayer 2.19.1

More version details

No response

Devices that reproduce the issue

Observed on Android OS 11-14, could include more.

Devices that do not reproduce the issue

No response

Reproducible in the demo app?

Not tested

Reproduction steps

1. Implement a playback scenario with multiple periods or ads, ensuring the playback queue has distinct playing and reading periods.
2. Induce a renderer error during playback, specifically when the playing period differs from the reading period.
3. Observe the handling of discontinuity events following the renderer error, particularly the reporting of non-internal discontinuity reasons (Player.DISCONTINUITY_REASON_AUTO_TRANSITION) in quick succession or across different parts of the playback queue.

It's also manually reproducible in unit tests by instantiating PlaybackInfoUpdate and invoking setPositionDiscontinuity multiple times with non-internal events, i.e.

    // rapidly set position discontinuity
    playbackInfoUpdate.setPositionDiscontinuity(Player.DISCONTINUITY_REASON_SEEK);
    playbackInfoUpdate.setPositionDiscontinuity(Player.DISCONTINUITY_REASON_INTERNAL);
    playbackInfoUpdate.setPositionDiscontinuity(Player.DISCONTINUITY_REASON_SEEK);

Here's a draft PR showing the issue google/ExoPlayer#11392

Expected result

No assert or unit test failures.

Actual result

In production we've seen app crashes with the following stack-trace:

java.lang.IllegalArgumentException: null
    at com.google.android.exoplayer2.util.Assertions.checkArgument
    at com.google.android.exoplayer2.ExoPlayerImplInternal$PlaybackInfoUpdate.setPositionDiscontinuity(SourceFile:121)
    at com.google.android.exoplayer2.ExoPlayerImplInternal.handlePositionDiscontinuity(SourceFile:2489)
    at com.google.android.exoplayer2.ExoPlayerImplInternal.handleMessage(SourceFile:626)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loopOnce(Looper.java:210)
    at android.os.Looper.loop(Looper.java:299)
    at android.os.HandlerThread.run(HandlerThread.java:67)

We began seeing this exception after upgrading from Exoplayer 2.13.3 to 2.19.1. This stack-trace follows a path introduced in commit 79b688e. It occurs across a broad range of Android OS (mostly 11-14) and Android device class.

Media

Not applicable

Bug Report

• You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.

[tonihei]

Thanks for reporting! Reporting multiple non-internal discontinuities is not expected to happen within the same iteration generally, but the logic added in 79b688e is special in that it can run after nearly every other piece of code in this class and needs to handle the potential for other pending events.