1381478 - Always have a frame ready to be painted

Status: NEW

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

Description

[Jean-Yves Avenard [:jya]]

A source of intermittent in the past has been due to readyState changing in the HTMLMediaElement while there was no frame to be painted.

That is because we may not have a received an image yet, though we do know the image duration.

The current approach is very hackish, where we move back the readyState to HAVE_METADATA if we haven't painted on the canvas yet:

https://dxr.mozilla.org/mozilla-central/source/dom/html/HTMLMediaElement.cpp#5753

We could instead always have a frame ready to be painted, even if none has been received yet. A black frame will do.

Comment 1

[Jean-Yves Avenard [:jya]]

s/though we do know the image duration/though we do know the image dimensions

Comment 2

[Andreas Pehrson [:pehrsons]]

If we are playing an audio-only MediaStream and add a video track to said stream, we won't know the video dimensions yet. How would you draw that into a canvas?

You could fairly easily make a case with a stream (per above) played in a video element, which is drawn to a canvas, which is captured to a stream, which is recorded by MediaRecorder -- and every recording would start with a black frame of arbitrary size. I'm not convinced that would be better than the current hackish solution.

Comment 3

[Jean-Yves Avenard [:jya]]

(In reply to Andreas Pehrson [:pehrsons] from comment #2)
> If we are playing an audio-only MediaStream and add a video track to said
> stream, we won't know the video dimensions yet. How would you draw that into
> a canvas?

have a dummy frame of a given size.

Comment 4

[Bulk Bug Changes for mreavy's org]

Mass change P1->P2 to align with new Mozilla triage process

Comment 5

[Sylvestre Ledru [:Sylvestre]]

Moving to p3 because no activity for at least 1 year(s).
See https://github.com/mozilla/bug-handling/blob/master/policy/triage-bugzilla.md#how-do-you-triage for more information