1496529 - [webrtc]H264 video decoding cause a crash/failure when using playback decoder.

Status: RESOLVED FIXED

(Core :: WebRTC: Audio/Video, enhancement, P3)

Description

[Jean-Yves Avenard [:jya]]

It crashes there:
https://searchfox.org/mozilla-central/rev/924e3d96d81a40d2f0eec1db5f74fc6594337128/dom/media/platforms/wrappers/H264Converter.cpp#334

    mDecoder->Init()
      ->Then(
        AbstractThread::GetCurrent()->AsTaskQueue(),
 
When called from webrtc.org, the current thread isn't a TaskQueue (nor nsIEventTarget)

As such, dispatching will fail (and assert on debug build)

Either we need to write a TaskQueue using a webrtc.org thread, or modify the H264Convert to use the decoder's taskqueue.

The later seems easier.

Comment 1

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P1. Pass OptionSet to H264 decoder

Comment 2

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P2. Make H264Converter use provided decoder's TaskQueue.

The H264Converter can be used on a thread that isn't a nsThread or a TaskQueue, so having the H264Converter dispatching tasks isn't going to work

So instead we run all the code on the decoder's taskqueue using promise chaining.
All internal methods are made to assert that they are running on the task queue accordingly

Depends on D7860

Comment 3

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P3. Make the Apple H264 decoder provide 0 latency option.

When used with the LowLatency option, we guarantee that the stream will contain no B-frame, as such we can reduce the re-ordering queue to zero. The apple VT decoder already returns frames in decode order making this change trivial.

Depends on D7861

Comment 4

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P4. Remove unnecessary code.

TaskQueue no longer requires explicit shutdown

Depends on D7862

Comment 5

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P5. Don't unnecessarily wait on decoder to shutdown

Depends on D7864

Comment 6

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P6. Always run EMEDecryptor on the decoder's taskqueue.

P2 changed the way the H264Converter would be calling the decoder. The assumption in the EMEDecryptor was pretty incorrect to start with.

Depends on D7865

Comment 7

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P7. Pass full range of CreateDecoderParam::Option to RemoteVideoDecoder

Depends on D7882

Comment 8

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P8. Add media.navigator.mediadatadecoder_h264_enabled preference.

For now, the H264 decoding support is rather sturdy. It handles change of resolution and content smoothly thanks to the H264Converter.
The VP8/VP9 one however, not so much.

So we make a preference to only enable H264 for now.

Depends on D7895

Comment 9

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P9. Enable low latency decoding on Windows.

Depends on D7908

Comment 10

[Jean-Yves Avenard [:jya]]

Attachment: Bug 1496529 - P10. Add to libvpx decoder low latency mode.

Depends on D7909

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f2b367bc188a
P2. Make H264Converter use provided decoder's TaskQueue. r=bryce
https://hg.mozilla.org/integration/autoland/rev/19cdb829699f
P3. Make the Apple H264 decoder provide 0 latency option. r=bryce
https://hg.mozilla.org/integration/autoland/rev/b76ae0d758d9
P4. Remove unnecessary code. r=bryce
https://hg.mozilla.org/integration/autoland/rev/93312ff3f180
P5. Don't unnecessarily wait on decoder to shutdown r=bryce
https://hg.mozilla.org/integration/autoland/rev/40f7fbd43f51
P6. Always run EMEDecryptor on the decoder's taskqueue. r=bryce
https://hg.mozilla.org/integration/autoland/rev/970b4aaccd35
P7. Pass full range of CreateDecoderParam::Option to RemoteVideoDecoder r=bryce
https://hg.mozilla.org/integration/autoland/rev/357d4762fa8f
P8. Add media.navigator.mediadatadecoder_h264_enabled preference. r=drno
https://hg.mozilla.org/integration/autoland/rev/ea2cd3e66c56
P9. Enable low latency decoding on Windows. r=bryce
https://hg.mozilla.org/integration/autoland/rev/b3a1baa85807
P10. Add to libvpx decoder low latency mode. r=bryce

Comment 12

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/f2b367bc188a
https://hg.mozilla.org/mozilla-central/rev/19cdb829699f
https://hg.mozilla.org/mozilla-central/rev/b76ae0d758d9
https://hg.mozilla.org/mozilla-central/rev/93312ff3f180
https://hg.mozilla.org/mozilla-central/rev/40f7fbd43f51
https://hg.mozilla.org/mozilla-central/rev/970b4aaccd35
https://hg.mozilla.org/mozilla-central/rev/357d4762fa8f
https://hg.mozilla.org/mozilla-central/rev/ea2cd3e66c56
https://hg.mozilla.org/mozilla-central/rev/b3a1baa85807