[pulseaudio-discuss] 0.9.8 - Invalid value for card

Jim Duda jim at duda.tzo.com
Thu Mar 27 10:27:30 PDT 2008

Yes, I do understand that I can only get PCM stereo through the spdif using pulseaudio at this time (no AC3/DTS).

My understanding (from reading all the posts) is that it's really a flaw with ALSA, which pulseaudio doesn't have a 
means to resolve (poor API with alsa spdif support).

I really would love pulseaudio with AC3/DTS passthrough, but I understand we don't have it yet.

I'm really just playing with stereo support through spdif at this time.

What might be a useful interim solution is to use the alsa a52 encoder.

The alsa a52 encoder will take a 6 channel "analog" audio source and encode it to a52 digital and then route out the 
spdif port.  It has worked very well for me to upmix 2 channel stereo to 6 channel a52.

In .asoundrc, I have:

pcm.a52encode {
    type a52

I was hoping to route 6 channel "analog" through this alsa pcm.  I haven't been able to get pulseaudio to use this pcm 


lroom# pulseaudio --system -v
I: core-util.c: Successfully gained nice level -11.
I: main.c: Found user 'pulse' (UID 499) and group 'pulse' (GID 499).
I: main.c: Successfully dropped root privileges.
W: main.c: setrlimit(RLIMIT_NICE, (31, 31)) failed: Operation not permitted
W: main.c: setrlimit(RLIMIT_RTPRIO, (9, 9)) failed: Operation not permitted
I: main.c: Page size is 4096 bytes
I: main.c: Dude, your kernel stinks! The chef's recommendation today is Linux with high-resolution timers enabled!
ALSA lib conf.c:3949:(snd_config_expand) Unknown parameters {AES0 0x6 AES1 0x82 AES2 0x0 AES3 0x2 }
ALSA lib pcm.c:2145:(snd_pcm_open_noupdate) Unknown PCM iec958:{AES0 0x6 AES1 0x82 AES2 0x0 AES3 0x2 }
E: alsa-util.c: Error opening PCM device a52encode: Invalid argument
E: module.c: Failed to load  module "module-alsa-sink" (argument: "device=a52encode"): initialization failed.
E: main.c: Module load failed.
E: main.c: failed to initialize daemon.
I: main.c: Daemon terminated.

lroom# cat /var/run/pulse/.asoundrc
pcm.a52encode {
    type a52

"Lennart Poettering" <lennart at poettering.net> wrote in message news:20080327125418.GA8862 at tango.0pointer.de...
> On Thu, 27.03.08 09:11, Colin Guthrie (gmane at colin.guthr.ie) wrote:
>> Jim Duda wrote:
>> > I need to use the spdif port, as this computer is attached to a DTS decoder/receiver.
>> I'm pretty sure you can't use spdif with pulse at the moment as ac3
>> passthrough is not supported. I think Lennart posted as much on this
>> list on a different thread the other day.
> Uh? spdif can also carry DAT style audio (PCM, 48khz, 16bit, stereo)
> and CD style audio.
> Unfortunately I have no spdif hw around to test this. But in theory PA
> should be able to support spdif:0 just fine, in one of these PCM modes.
> Lennart
> -- 
> Lennart Poettering                        Red Hat, Inc.
> lennart [at] poettering [dot] net         ICQ# 11060553
> http://0pointer.net/lennart/           GnuPG 0x1A015CC4 

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