1368794 - dash webm VP9 audio plays, video does not

Status: RESOLVED INVALID

(Core :: Audio/Video: Playback, defect, P1)

Description

[ranvel]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:54.0) Gecko/20100101 Firefox/54.0
Build ID: 20170529025115

Steps to reproduce:

Go to this page, click to play the video: 
http://sites.ranvel.com/webmtest/



Actual results:

Audio plays, video does not. 


Expected results:

Both audio and video play. This is the behaviour of both the stable (53)  and nightly (55) branches. Only the beta branch is affected.

Comment 1

[Blake Wu [:bwu][:blakewu]]

Thanks for firing this bug. 
I can see this problem on the release version, 53.0.3 (64-bit), on my Mac.

Comment 2

[Blake Wu [:bwu][:blakewu]]

I tried to play the link in comment 0 on Beta, 54.0b12 (64-bit), and the latest nightly, 55.0a1 (2017-05-30) (64-bit). 
They both cannot play that link.

Comment 3

[ranvel]

I think these are actually two different issues. The issue that I wrote about in comment 0 only affects Firefox 54. I just tested it in 54.0b12 (64 bit). 

I just tested it again in Nightly (55.0a1) (2017-05-30) and 53.0.03 (64 bit) and they both work fine. 

The issue where it doesn't work at all (in stable/beta/nightly channels) I think has to do with the way Firefox (tries to) process webm video by using hardware acceleration. (It only happens on some systems and may be related to not having a discrete graphics card).

Comment 4

[Jean-Yves Avenard [:jya]]

50, 51, 52 and 53 (from nightly build) do not play video either.

Can reproduce with nightly debug build.

Comment 5

[Jean-Yves Avenard [:jya]]

something is wrong with this player. it typically calls addSourceBuffer("audio/webm; codecs="vorbis") and that's it. never creating the video source buffer.

Issue should be reported to shaka.

nothing wrong in the behaviour of firefox here.

My guess it doesn't like the use of a single webm file for both init and media segment , and a big one at that.

Comment 6

[Blake Wu [:bwu][:blakewu]]

(In reply to Jean-Yves Avenard [:jya] from comment #5)
> something is wrong with this player. it typically calls
> addSourceBuffer("audio/webm; codecs="vorbis") and that's it. never creating
> the video source buffer.
> 
> Issue should be reported to shaka.
> 
> nothing wrong in the behaviour of firefox here.
> 
> My guess it doesn't like the use of a single webm file for both init and
> media segment , and a big one at that.
Is it against spec by doing so?  
FWIW, Chrome can play that link well.

Comment 7

[Jean-Yves Avenard [:jya]]

It isn't against the spec. But if they create a single sourceBuffer for an audio track only, video will never be played. Now that is per spec.

It's irrelevant what Chrome does in this particular case as the issue is with the DASH player that is being used here (shaka). It is shaka that from the DASH manifest (http://sites.ranvel.com/webmtest/manifest.mpd) calls the proper MSE functions.

There's nothing we can do here if the DASH player doesn't call the proper function.

I can't tell what version of the shaka player is used there, maybe a newer version would fix this bug I don't know..

But only the shaka folks can fix this problem

Comment 8

[Jean-Yves Avenard [:jya]]

I got it to work from time to time, it is intermittent.

It takes a fair while to download the media segment (20s+ here) maybe there's a timeout issue that it doesn't even try.. I'm only guessing. I'm not going to debug a JS several MB in length when I know for certain the issue isn't in Firefox