1349474 - Support more AudioChannelLayoutTag than kAudioChannelLayoutTag_UseChannelDescriptions in cubeb_audiounit

Status: RESOLVED INVALID

(Core :: Audio/Video: cubeb, enhancement, P3)

Description

[C.M.Chang[:chunmin]]

We only support kAudioChannelLayoutTag_UseChannelDescriptions in cubeb_audiounit.cpp[0] currently. We need to kAudioChannelLayoutTag_UseChannelBitmap and kAudioFormatProperty_ChannelLayoutForTag also.

[0] http://searchfox.org/mozilla-central/rev/0079c7adf3b329bff579d3bbe6ac7ba2f6218a19/media/libcubeb/src/cubeb_audiounit.cpp#1131
[1] http://searchfox.org/mozilla-central/rev/0079c7adf3b329bff579d3bbe6ac7ba2f6218a19/dom/media/platforms/apple/AppleATDecoder.cpp#481

Comment 1

[C.M.Chang[:chunmin]]

Need to figure out what cases we will get mChannelLayoutTag = kAudioChannelLayoutTag_UseChannelBitmap or kAudioFormatProperty_ChannelLayoutForTag. Maybe we need a device. The reference is [1] above.

Comment 2

[C.M.Chang[:chunmin]]

Attachment: pull on github

Comment 3

[C.M.Chang[:chunmin]]

Hi jya,
Do you know when |AudioChannelLayout->mChannelLayoutTag != kAudioChannelLayoutTag_UseChannelDescriptions|[0] is true?
I mean, how to let the tag to be kAudioChannelLayoutTag_UseChannelBitmap or other values? 

[0] https://github.com/kinetiknz/cubeb/pull/276/commits/956ffbedd6d03b942c177f32015fd19e46a39074#diff-148fe3e6ebf13351ba4d886b1b4898d2R1139

Comment 4

[Jean-Yves Avenard [:jya]]

I don't know this structure, nor its member.

gecko will always call cubeb with SMPTE channel layout.

Comment 5

[Jean-Yves Avenard [:jya]]

Should have read the code first I guess and that it's about AudioUnit.

I haven't played with AudioUnit in years unfortunately, and my memory on the matter is rather fuzzy.

It all depends on what audio card you will be using and if the user has defined a custom channel layout using the Audio MIDI Setup utility...

You may want to ask your question in Apple's CoreAudio mailing list.

Comment 6

[C.M.Chang[:chunmin]]

(In reply to Jean-Yves Avenard [:jya] from comment #5)
> Should have read the code first I guess and that it's about AudioUnit.
> 
> I haven't played with AudioUnit in years unfortunately, and my memory on the
> matter is rather fuzzy.
> 
> It all depends on what audio card you will be using and if the user has
> defined a custom channel layout using the Audio MIDI Setup utility...
> 
> You may want to ask your question in Apple's CoreAudio mailing list.

OK, thanks for your reply.

If I find the answer, I'll also test similar code[0] using AudioChannelLayoutTag in gecko.
[0] http://searchfox.org/mozilla-central/rev/0079c7adf3b329bff579d3bbe6ac7ba2f6218a19/dom/media/platforms/apple/AppleATDecoder.cpp#481

Comment 7

[Jean-Yves Avenard [:jya]]

(In reply to Chun-Min Chang[:chunmin] from comment #6)
> (In reply to Jean-Yves Avenard [:jya] from comment #5)
> > Should have read the code first I guess and that it's about AudioUnit.
> > 
> > I haven't played with AudioUnit in years unfortunately, and my memory on the
> > matter is rather fuzzy.
> > 
> > It all depends on what audio card you will be using and if the user has
> > defined a custom channel layout using the Audio MIDI Setup utility...
> > 
> > You may want to ask your question in Apple's CoreAudio mailing list.
> 
> OK, thanks for your reply.
> 
> If I find the answer, I'll also test similar code[0] using
> AudioChannelLayoutTag in gecko.
> [0]
> http://searchfox.org/mozilla-central/rev/
> 0079c7adf3b329bff579d3bbe6ac7ba2f6218a19/dom/media/platforms/apple/
> AppleATDecoder.cpp#481

That's a different thing altogether. Same constant name, but different use.
It's for the decoder, and is already properly handled. This is to define when the codec explicitly defines a channel layout, this is used to convert to SMPTE.

AAC can defined either a number of channels, or an explicit channel layout. AFAIK, only the Apple AAC decoder supports it.

Comment 8

[C.M.Chang[:chunmin]]

(In reply to Jean-Yves Avenard [:jya] from comment #7)
> That's a different thing altogether. Same constant name, but different use.
> It's for the decoder, and is already properly handled. This is to define
> when the codec explicitly defines a channel layout, this is used to convert
> to SMPTE.
> 
> AAC can defined either a number of channels, or an explicit channel layout.
> AFAIK, only the Apple AAC decoder supports it.

Oh, I see. They should be totally unrelated. One gets the layout from decoder, and the other gets from underlying audio interface directly. Thanks!

Comment 9

[Bulk Bug Changes for mreavy's org]

Mass change P2->P3 to align with new Mozilla triage process.