1300711 - Remove MediaDecoderStateMachine::mQuickBuffering

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, defect, P3)

Description

[JW Wang [:jwwang] [:jw_wang]]

https://hg.mozilla.org/mozilla-central/file/tip/dom/media/MediaDecoderStateMachine.h#l825

I think we can remove this member now because MDSM prerolls enough audio/video before starting playback to ensure it won't enter buffering immediately after playback starts.

Comment 1

[Chris Pearce [:cpearce (Not reading bugmail)]]

Worth testing. You can use https://github.com/cpearce/HttpMediaServer or something similar to limit the bandwidth that video files are served over, and use that to ensure buffering happens.

Comment 2

[JW Wang [:jwwang] [:jw_wang]]

After fixing bug 1302040 and bug 1302045, MDSM will not enter buffering prematurely at the beginning of playback.

Here are the test results after removing quick buffering:
1. When download is slow (ex: rate=200), it enters buffering 2 or 3 secs after playback starts.
2. When download is fast enough (ex: rate=500), no buffering happens during playback.

Without removing quick buffering:
1. When download is slow (ex: rate=200), it enters quick buffering 2 or 3 secs after playback starts, and exits quick buffering one sec later, and then enters buffering again 3 or 4 sec later.

So I conclude quick buffering doesn't buy us much. If download is slow, we will need to stop for buffering anyway some time. The point of quick buffering is to prevent entering buffering right after playback starts. Since prerolling + bug 1302040 + bug 1302045 have fix that, there is not point keeping quick buffering anymore.

Comment 3

[JW Wang [:jwwang] [:jw_wang]]

Attachment: Bug 1300711 - Remove MediaDecoderStateMachine::mQuickBuffering.

Review commit: https://reviewboard.mozilla.org/r/79448/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/79448/

Comment 4

[Chris Pearce [:cpearce (Not reading bugmail)]]

Comment on attachment 8792376 [details]
Bug 1300711 - Remove MediaDecoderStateMachine::mQuickBuffering.

https://reviewboard.mozilla.org/r/79448/#review78316

I always thought quick buffering was a hack. Good riddance!

Comment 5

[JW Wang [:jwwang] [:jw_wang]]

Thanks!

Comment 6

[JW Wang [:jwwang] [:jw_wang]]

Comment on attachment 8792376 [details]
Bug 1300711 - Remove MediaDecoderStateMachine::mQuickBuffering.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/79448/diff/1-2/

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9a5ccc0e7270
Remove MediaDecoderStateMachine::mQuickBuffering. r=cpearce

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/9a5ccc0e7270