Bug 302160 – [MSE][GStreamer] Early reset m_isEndReached (EOS) when about to seek

• Component: New Bugs
• Status: RESOLVED FIXED

[Enrique Ocaña]

When a video has reached End Of Stream and a (backwards) seek is done, the media player won't ever complete the seek in some cases because the EOS condition is still in place and no buffers are ever going to be pushed. A Successful seek completion would reset the EOS condition, but that won't happen since the seek won't even start.

See: https://github.com/WebPlatformForEmbedded/WPEWebKit/pull/1568

Unfortunately, this problem can be only reproduced downstream, so any patch submitted will only work there and having it upstream will only be a preventive measure for upgrades to future versions.

[Enrique Ocaña]

Pull request: https://github.com/WebKit/WebKit/pull/53592

[Enrique Ocaña]

Created attachment 477391 [details]
Test case that triggers the original problem downstream

This test case is a modification of the one provided in https://github.com/WebPlatformForEmbedded/WPEWebKit/pull/1568, with some more extra console.log() to help undertand better the different steps exercised.

[Enrique Ocaña]

Created attachment 477392 [details]
Annotated filtered log of the test case

Annotated filtered log of the provided test case, ran on a Raspberry Pi 3 using downstream debug branch https://github.com/WebPlatformForEmbedded/WPEWebKit/commits/eocanha/eocanha-debug-158/ , based on wpe-2.48 plus a bunch of extra log lines and the m_isEndReached reset fix commented out to trigger the error again on purpose.

This file has ANSI color codes. View it by using `cat` on a terminal emulator.

This file shows how m_isEndReached being true triggers a series of events that end up on both HTMLMediaElement and MediaPlayerPrivateGStreamer/MediaPlayerPrivateGStreamerMSE paused and without any intention to play again after a seek.

The proposed patch would have reset m_isEndReached after a seek to a position lower than the duration. This would have prevented the series of events happening and the video would have properly played after the seek.

[EWS]

Committed 303186@main (4b36b57f5261): <https://commits.webkit.org/303186@main>

Reviewed commits have been landed. Closing PR #53592 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/164973649>