884651 - Gstreamer using 100% cpu

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Anthony Jones (:ajones, :kentuckyfriedtakahe, :k17e)]

Steps to reproduce:

* Enable gstreamer pref
* Go to http://www.quirksmode.org/html5/tests/video.html

Expected results:

CPU isn't busy.

Actual results:

CPU is 100% busy.

Comment 1

[Edwin Flores [inactive from 2016-12-01] [:eflores] [:edwin]]

Doesn't look to me like it's actually pegging a CPU.

On my machine top *does* report 100% CPU usage, but looking closer it's just four cores each being used at 25%. Probably the ffmpeg software decoder.

Comment 2

[Anthony Jones (:ajones, :kentuckyfriedtakahe, :k17e)]

The CPU load goes up without playing the video.

Comment 3

[Edwin Flores [inactive from 2016-12-01] [:eflores] [:edwin]]

Attachment: Fix

gstreamer usually syncs audio and video for clients so they don't have to deal with it -- stopping audio from coming down the pipeline if it's ahead of video, or vice versa. In our case, we just want |AmpleVideoFrames| video frames and |AmpleAudioUsecs| audio usecs, which can differ considerably (time-wise). So we'll end up being starved of one or the other until we start playback.

This patch just disables the gstreamer audio/video sync because we already do that and it's just getting in the way.

Comment 4

[Alessandro Decina]

This makes sense. I would add a comment explaining that we run with sync disabled otherwise DecodeAudioData and DecodeVideoFrame can get called in a tight loop, and that gst threads will still block on max-buffers (and not decode everything) if ffox threads can't keep up.

Comment 5

[Edwin Flores [inactive from 2016-12-01] [:eflores] [:edwin]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/0e276ed2d7c3

Comment 6

[Phil Ringnalda (:philor)]

Backed out in http://hg.mozilla.org/integration/mozilla-inbound/rev/a36ee93e4159 for https://tbpl.mozilla.org/php/getParsedLog.php?id=24542138&tree=Mozilla-Inbound

Comment 7

[Edwin Flores [inactive from 2016-12-01] [:eflores] [:edwin]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/73dff4338b06

Comment 8

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/73dff4338b06