[pulseaudio-discuss] Cannot have iec958:0 and a52:0 simultaneously?

[Michael Rans]

I have a theory that the $CARD doesn't work for me and may not for others 
because of the way in which the %f in a52:%f is generated.

Would I be right in saying that %f is incremented for each source or sink ie. 
you cannot have both iec958:0 and a52:0?

I see in my logs:
I: alsa-source.c: Successfully opened device hw:2.
I: alsa-mixer.c: Successfully attached to mixer 'hw:2'
...
I: alsa-sink.c: Successfully opened device iec958:0.
I: (alsa-lib)control.c: Invalid CTL iec958:0
I: alsa-mixer.c: Unable to attach to mixer iec958:0: No such file or directory
I: alsa-mixer.c: Successfully attached to mixer 'hw:0'
...
I: alsa-sink.c: Successfully opened device hdmi:1.
I: (alsa-lib)control.c: Invalid CTL hdmi:1
I: alsa-mixer.c: Unable to attach to mixer hdmi:1: No such file or directory
I: alsa-mixer.c: Successfully attached to mixer 'hw:1'

I also see:
D: alsa-mixer.c: Checking for playback on Digital Surround 5.1 (IEC958/AC3) 
(iec958-ac3-surround-51)
D: alsa-util.c: Trying a52:0 with SND_PCM_NO_AUTO_FORMAT ...
D: alsa-util.c: Managed to open a52:0
D: alsa-util.c: Maximum hw buffer size is 21824 ms
D: alsa-util.c: Set buffer size first (to 3840 samples), period size second (to 
480 samples).
D: alsa-mixer.c: Profile output:iec958-ac3-surround-51 supported.

But no "Successfully opened a52:0". My theory is that because :0 is already 
taken by iec958:0, Pulseaudio doesn't accept the a52:0 sink.

If I replace $CARD with 0, my log says:
I: alsa-sink.c: Successfully opened device a52:1.

Do you think my theory is correct? If not, any better one?

Cheers,
Mike





________________________________
From: pl bossart <bossart.nospam at gmail.com>
To: General PulseAudio Discussion <pulseaudio-discuss at mail.0pointer.de>
Sent: Tue, 13 July, 2010 21:21:50
Subject: Re: [pulseaudio-discuss] {PATCH][RFC] AC3 passthrough support

Adding this in /etc/asound.rc (more exactly
/etc/alsa/pulse-default.conf on my Fedora box) work fine:

pcm.a52 {
   @args [CARD]
   @args.CARD {
       type string
   }
   type rate
   slave {
       pcm {
           type a52
           bitrate 448
           channels 6
           card $CARD
       }
       rate 48000 #required somehow, otherwise nothing happens in PulseAudio
   }
}

a52:0 is detected by PulseAudio and the encoded output shows as
'Digital Surround 5.1 (IEC958/AC3) in pavucontrol.


      
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