[pulseaudio-discuss] association of pa_stream to mixer input channel

[jayan john]

Thanks Col! That addresses my query perfectly. By "mixer" I meant a DSP that "mixes and routes" multiple analog and digital inputs to analog (5.1) or digital output.
 
I am working on the implementation of a audio policy management module using PA. It requires me to understand both ;) the use of pulseaudio by apps and the implementation of PA/ ALSA mixer or sound card drivers on an automotive platform.
 
~J
jayan_john at hotmail.com
"Woking on Meego, breaking in PulseAudio"
 
> To: pulseaudio-discuss at lists.freedesktop.org
> From: gmane at colin.guthr.ie
> Date: Tue, 14 Jun 2011 09:51:00 +0100
> Subject: Re: [pulseaudio-discuss] association of pa_stream to mixer input channel
> 
> 'Twas brillig, and jayan john at 14/06/11 06:12 did gyre and gimble:
> > 1. Does the pa_stream_connect_playback() call allocate an input channel
> > on the mixer and connect it to the sink device?
> 
> Not really what you are referring to as "the mixer" or an "allocated
> input channel" here but this command does indeed connect a playback
> stream. This will be needed if you want to playback any audio. After the
> stream is connected it will be allocated to a sink according to various
> routing decisions in PA itself. It may at some point be moved to a new
> device at a later time (unless you pass the PA_STREAM_DONT_MOVE flag IIRC).
> 
> > 2. Would it allocate 6 input channels on the mixer if I have a 5.1
> > channel map for my pa_stream?
> 
> Again, I'm not really sure what "the mixer" refers to here. But your
> stream will have as many channels as you say it has in it's channel map
> like you say. You can ultimately connect a stereo stream to a 5.1 sink
> and PA will upmix, and likewise you can connect a 6ch stream to a stereo
> sink and it will downmix.
> 
> Ultimately, as an app developer, you should just care about your stream
> and not worry about the sinks :)
> 
> Col
> 
> 
> -- 
> 
> Colin Guthrie
> gmane(at)colin.guthr.ie
> http://colin.guthr.ie/
> 
> Day Job:
> Tribalogic Limited [http://www.tribalogic.net/]
> Open Source:
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> 
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