899050 - No sound with STEREO output.

Status: VERIFIED FIXED

(Core :: Audio/Video, defect)

Description

[Alice0775 White]

Build Identifier:
http://hg.mozilla.org/mozilla-central/rev/73b69c146ca6
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20130728 Firefox/25.0 ID:20130728030204

This is spun off from Bug 894801.
No sound with default STEREO output.
Bug 893307 does not fix.

Aurora24.0a2 works fine.
Nightly25.0a1 with media.gstreamer.enabled=true on ubuntu12.04 works fine.

So, this problem only happens on Nightly25.0a1 Windows7.

Steps To Reproduce
1. Open http://www.brucewiggins.co.uk/Audio/HTML5_51.m4a

Actual Results:
No sound play back

Exoected Results:
Sound should be play back

Regression window(m-i)
Good:
http://hg.mozilla.org/integration/mozilla-inbound/rev/26f83c4cb81e
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20130709 Firefox/25.0 ID:20130709022917
Bad: no sound
http://hg.mozilla.org/integration/mozilla-inbound/rev/ebdf97f9ec52
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20130709 Firefox/25.0 ID:20130709030058
Pushlog:
http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=26f83c4cb81e&tochange=ebdf97f9ec52

Regressed by:
ebdf97f9ec52	Paul Adenot — Bug 866675 - Add a WASAPI backend to cubeb. r=kinetik

Comment 1

[Paul Adenot (:padenot)]

Right, this is a multichannel file, I had not looked closely at the file before. Not sure what the problem is, though, because the decoders are supposed to downmix it to stereo, and thus request a stereo cubeb stream, later upmixed in WASAPI. I'll see what happens.

Comment 2

[Paul Adenot (:padenot)]

What happens here is that we don't downmix multichannel files at the decoder level when using WMF (we do when using opus or vorbis).

Before WASAPI, we were using winmm, that handled everything for us (sample rate conversion, channel mapping, etc.). WASAPI wants the developer to write everything, so we will need to handle the downmix.

It seems a nicer solution anyway, to handle the downmix at the output stream level rather than at the decoder level.

Comment 3

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/f74f1e59dc50

Comment 4

[Paul Adenot (:padenot)]

Ha, it seems that I mixed up bug numbers when pushing this one, this is not fixed.

Comment 5

[Paul Adenot (:padenot)]

Attachment: wasapi-downmix

This make WASAPI behave in the same way as the winmm backend, dropping the channels we can't render.

We can't really do a proper downmixing here (with a downmix matrix of weights and channels). We would need to do at least one of the following:
- Send channel mapping info to cubeb so it can remap (using platform facilities in some backends, manually in other backends).
- Normalize the channel mapping in the *Reader output, and decide of a channel mapping in cubeb.

Comment 6

[Matthew Gregan [:kinetik]]

Comment on attachment 814880 [details] [diff] [review]
wasapi-downmix

Review of attachment 814880 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks for the ping email, I'm still traveling so might not have seen the r? for a couple of days.

Comment 7

[Paul Adenot (:padenot)]

Comment on attachment 814880 [details] [diff] [review]
wasapi-downmix

[Approval Request Comment]
Bug caused by (feature/regressing bug #): bug 866675
User impact if declined: No sound when playing a multichannel file (I believe this is extremely rare)
Testing completed (on m-c, etc.): try, locally
Risk to taking this patch (and alternatives if risky): no very risky. Alternative is to backout the wasapi backend for this cycle.
String or IDL/UUID changes made by this patch: none.

Comment 8

[Lukas Blakk [:lsblakk] use ?needinfo]

Comment on attachment 814880 [details] [diff] [review]
wasapi-downmix

Let's get this on Aurora, will leave it up to Alex to decide if this can get into Beta at this late stage.

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/18c8f9d64847

Comment 10

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/18c8f9d64847

Comment 11

[Paul Adenot (:padenot)]

https://hg.mozilla.org/releases/mozilla-aurora/rev/8ff026eb8754

Comment 12

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/deab85933daa

Comment 13

[Ekanan Ketunuti]

Verified on
- Firefox 25.0b8
- Aurora 26.0a2 buildid 20131015004002
- Nightly 27.0a1 buildid 20131015030319

Comment 14

[u279076]

Thanks for your help Ekanan.