[pulseaudio-discuss] [PATCH]: High-definition audio pass-through support

Kelly Anderson kelly at silka.with-linux.com
Sat Nov 19 10:55:47 PST 2011

On 11/19/2011 11:36 AM, Pierre-Louis Bossart wrote:
>> Isn't this just enabling 7.1 channel output, such that the application
>> in question does the decoding and passes the PCM stream to your
>> receiver
>> equipment?
>> This isn't necessarily a bad thing to support, but I think the commit
>> message and such is then quite wrong (and judging from your comments,
>> perhaps your understanding of what is going on too might be quite off
>> target!)
> Enabling multichannel output over HDMI probably something we want to do by
> reading the ELD controls. Adding static profile definitions doesn't make
> sense to me, it's dependent on the receiver capabilities.
I agree with that.  It would be ideal to be able to make a single api 
call to determine
which modes are supported, and then be able to make a call to set the 
profile.  This would allow me to determine whether I can pass-through DTS-HD
properly or whether stripping the DTS core would be more apppropriate
for a particular receiver.

The real problem that I ran into with the code as it is, is that 
changing the channel
count from 2 to 8 when opening the device in pass-through mode would fail.
So I added an 8 channel profile and 8 channel passthrough works.  What I've
discovered recently though, is that the non-HD data streams are not working
properly now that I've defaulted to 8 channels.

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