[pulseaudio-discuss] Emulate Alsa A52 plugin in pulseaudio ?

Jim Duda jim at duda.tzo.com
Fri Feb 29 08:22:29 PST 2008


"Tanu Kaskinen" <tanuk at iki.fi> wrote in message news:20080229052846.GA12761 at a9a.mannikko1.tontut.fi...
> On Thu, Feb 28, 2008 at 09:57:31PM -0500, Jim Duda wrote:
>> The first thing I need to do is to get the spdif port on my CMPCI to
>> work with pulseaudio.  I'm finding that defining an alsa-sink manually
>> using device surround51 doesn't work, I don't get any audio.
> Instead of surround51, try spdif.

Yes, spdif:0 works too, similiar to surround51, gives me 2 channel stereo.

>> Allowing pulseaudio to auto-detect does allow audio to work, but only
>> with 2 channels.
>> With auto-detection load-module module-detect, I get:
>> *** Sink #0 ***
>> Name: alsa_output.hw_0
>> Driver: modules/module-alsa-sink.c
>> Description: ALSA PCM on hw:0 (C-Media PCI DAC/ADC)
>> Sample Specification: s16le 2ch 44100Hz
>> Channel Map: front-left,front-right
>> Owner Module: 0
>> Volume: muted
>> Monitor Source: 0
>> Latency: 59501 usec
>> This above gives me stereo only through the spdif port.
> I don't know about module-detect, but module-hal-detect will
> by default use just two channels. The default is configured
> with default-sample-channels in daemon.conf.
> If you still don't have progress, I would think that one
> possible solution would be to run those programs that need
> AC-3 passthrough with pasuspender (e.g. start mplayer with
> command "pasuspender mplayer") and configure the programs to
> use the spdif device directly.

I will check out pasuspender, I would expect that to work.

I have yet to attempt any ac3 passthrough, I hope to test tonight.

>> If I used anything besides nothing or channels=2, I don't get any audio.
> Here I'm a bit confused - what do you give that parameter
> to? I thought you were talking about module-detect, but it
> doesn't accept that parameter.

load-module module-alsa-sink sink_name=ac3_raw device=spdif:0 channels=6

The parameter for alsa-sink.  Changing the channels has no effect with spdif, however, any value != 6 for surround51 
results in no audio.  I'm not sure this is important, just reporting the behavior I see.

> -- 
> Tanu Kaskinen 

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