[pulseaudio-discuss] 'Failed to find a working profile' for firewire sound devices

Takashi Sakamoto o-takashi at sakamocchi.jp
Sun Jan 12 05:30:31 PST 2014

Hi David,

 > AFAIK, the driver should support what the hardware supports.

Yes. It's my intent to add the rules between channels/rates.

Well, today I did some tests for an idea to use 'plug' plugin.

 > 1) Edit /usr/share/pulseaudio/alsa-mixer/profile-sets/default.conf
 > and change "hw:%f" to "plughw:%f" in the section
 > "Mapping analog-stereo". If the plughw plugin can upscale,
 > then that should make things work.

This wasn't good. Then I remembered this fact:

 > Hm. Actually PulseAudio tries opening "plug:hw:1" too and setting the
 > channel number to two fails in that case too. If the "plug" plugin can
 > change the number of channels, then that should have been working.

Then I debug PulseAudio/libasound in a point of 'how to open ALSA PCM 
handle'. I have an presumption that 'plug' plugin can upscale channels 
correctly if PulseAudio open 'plug:hw' device as the same way as 
normal-aplay open.

As a result, I got a conviction that 'SND_PCM_NO_AUTO_CHANNELS' flag 
for snd_pcm_open() disables upscaling.

I can reproduce it with this program (it's too rough):

So I conclude we cannot use 'plug' plugin for this purpose. Would you 
please confirm this in your side?

And for these two options below, I need more time to test.

 > To aid for applications, one can add custom per-card mapping in
 > alsa-lib - e g, look at /usr/share/alsa/cards/ICE1712.conf where you
 > can open the device "front:<card>" with two channels and it
 > automatically upscales to 10 or 12 channels.

 > 2) Alternatively, you could add channels to your mapping:
 > channel-map =
 > left,right,aux0,aux1,aux2,aux3,aux4,aux5,aux6,aux7,
 > aux8,aux9,aux10,aux11

Thanks for your help

Takashi Sakamoto
o-takashi at sakamocchi.jp

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