1194088 - Remove DECODER_STATE_WAIT_FOR_RESOURCES from MDSM

Status: NEW

(Core :: Audio/Video: Playback, defect, P5)

Description

[Alfredo Yang (:alfredo)]

After bug 1146086, it doesn't need to wait for resource on decoder based on PlatformDecoderModule. Except for some old playback engines, the WAIT_FOR_RESOURCE state can be removed from MDSM.


https://dxr.mozilla.org/mozilla-central/rev/9a6b1cc80245cb5a71d89bc9abd268a5ff20d53e/dom/media/MediaDecoderStateMachine.h#139

Comment 1

[Alfredo Yang (:alfredo)]

MSE uses WAITING_FOR_RESOURCES when a/v data is not available [1].
That causes problem when removing this state from MDSM.
Any suggestion?

[1] https://dxr.mozilla.org/mozilla-central/source/dom/media/MediaFormatReader.cpp#419

Comment 2

[Jean-Yves Avenard [:jya]]

We need to either:
1- rework the MediaDataDemuxer API so it doesn't resolve the init promise until it has all the data it needs
2- Implement a mechanism between the MediaSourceDemuxer and TrackBuffersManager so it can tell it when enough data is available to start processing the metadata. The difficulty here is that we do not want to introduce a reference cycle as this will cause massive leaks.

My guess is that 1 is the most elegant approach, albeit more work.

Let me take this one while I think about it a bit more

Comment 3

[Jean-Yves Avenard [:jya]]

Actually we could have option 3:
Have the MediaFormatReader not resolve the metadata promise and have it wait until new data is available which would then re-attempt to init the demuxer.

This is likely the easiest and quickest solution.

Comment 4

[Jean-Yves Avenard [:jya]]

Not taking it directly, as the remaining use for is for EME and waiting for the CDM to be ready.