1409727 - Add a pref to not skip frames

Status: RESOLVED FIXED

(Core :: Audio/Video: Recording, enhancement, P2)

Description

[Andreas Pehrson [:pehrsons]]

We'd need this for tests that record the screen (1080p, so quite slow) and then analyze the recording frame by frame.

Comment 1

[Andreas Pehrson [:pehrsons]]

Attachment: Bug 1409727 - Expose the audio node recording pref to about:config.

Review commit: https://reviewboard.mozilla.org/r/191100/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/191100/

Comment 2

[Andreas Pehrson [:pehrsons]]

Attachment: Bug 1409727 - Add a mode and pref to disallow frame drops in MediaRecorder.

Review commit: https://reviewboard.mozilla.org/r/191102/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/191102/

Comment 3

[Andreas Pehrson [:pehrsons]]

florian, can you check whether this patch works for you?

Comment 4

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

Comment on attachment 8920115 [details]
Bug 1409727 - Add a mode and pref to disallow frame drops in MediaRecorder.

https://reviewboard.mozilla.org/r/191102/#review196516

Comment 5

[Florian Quèze [:florian]]

(In reply to Andreas Pehrson [:pehrsons] from comment #3)
> florian, can you check whether this patch works for you?

I had already answered on IRC last week, but repeating here to clear the needinfo:

With your patch applied and the pref flipped, I get a consistent 60fps when the mediarecorder input is an existing video file captured at 60fps, played in a <video> and then captured through video.mozCaptureStream(), so I would say the patch works for me.

However I didn't see a significant difference when the input stream was coming directly from my HDMI recorder using getUserMedia.
So either there's another bug for that case, or I have a USB bandwidth issue on the macbook.

Comment 6

[Andreas Pehrson [:pehrsons]]

What if you're doing a screenshare? It probably doesn't have the same high framerate, but it does have large frames.

Can you see differences if you record with ffmpeg straight off the device instead? https://trac.ffmpeg.org/wiki/Capture/Webcam#Encodingexample1

I think it's possible for us to drop frames before the recorder when the source is getUserMedia too (that video.mozCaptureStream() wouldn't be exposed to). But it would be good to confim whether that is what is actually happening here.

Related: I was preparing a script for QA last week, I was going to tell you on IRC but you had just left. It can help you analyse frames in a recording: https://github.com/Pehrsons/plotbitrate

Comment 7

[Florian Quèze [:florian]]

The reason for missing frames with getUserMedia on Mac is bug 1412326.

Comment 8

[Jan-Ivar Bruaroey [:jib] (needinfo? me)]

Comment on attachment 8920114 [details]
Bug 1409727 - Expose the audio node recording pref to about:config.

https://reviewboard.mozilla.org/r/191100/#review200802

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ea9eada6667e
Expose the audio node recording pref to about:config. r=jib
https://hg.mozilla.org/integration/autoland/rev/baf693d2380d
Add a mode and pref to disallow frame drops in MediaRecorder. r=SingingTree

Comment 10

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/ea9eada6667e
https://hg.mozilla.org/mozilla-central/rev/baf693d2380d