Takashi Sakamoto | 3 Jul 01:45 2013
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[usb-audio] VIA/Audinst HUD-mx2: One of two PCM device is available for playback

Hi,

This sound card has two PCM devices. If the sound card is realized "card
0", there are "hw:0,0" and "hw:0,1". But former seems not to generate
sound and latter seems to generate.

This issue is reported to Ubuntu-jp and LinuxMint forum. The reporter
said this happens in Fedora18 so I think this does not depends on these
desktop invironment.
https://forums.ubuntulinux.jp/viewtopic.php?pid=98940#p98940
http://forums.linuxmint.com/viewtopic.php?f=49&t=128478

Please see attached lsusb.log to know usb information and alsainfo.sh in
detail.

Audinst HUD-mx2 applies VIA Technologies chip internally.
http://www.audinst.com/en/bbs/board.php?bo_table=HUDmx2&wr_id=4

The sound card has a lamp which turn on when data comes. When "hw:0,0"
is used, the lamp turns on but no sound. When "hw:0,1" is used, the lamp
turns on and sound.

My question is:
1. does hw:0,0 seem to be available when some control are changed?
2. are there some ways to use hw:0,1 as a default?

Regards

Takashi Sakamoto
o-takashi <at> sakamocchi.jp
(Continue reading)

Clemens Ladisch | 4 Jul 13:22 2013
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Re: [usb-audio] VIA/Audinst HUD-mx2: One of two PCM device is available for playback

Takashi Sakamoto wrote:
> This sound card has two PCM devices. If the sound card is realized "card
> 0", there are "hw:0,0" and "hw:0,1". But former seems not to generate
> sound and latter seems to generate.

This device has multiple alternate settings for PCM and AC-3 playback.
The driver creates multiple devices for those because it has no other
mechanism to distinguish them.

The AC-3 setting happens to be listed first in the descriptors.

> 2. are there some ways to use hw:0,1 as a default?

Entires like these in ~/.asoundrc or /etc/asound.conf:

  defaults.pcm.card 0
  defaults.pcm.device 1

I'd guess the driver could be changed to enumerate alternate settings in
two steps, first for PCM formats, then for others.

Regards,
Clemens
Takashi Sakamoto | 6 Jul 13:21 2013
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Re: [usb-audio] VIA/Audinst HUD-mx2: One of two PCM device is available for playback

Thanks Clemens,

 > This device has multiple alternate settings for PCM and AC-3 playback.
 > The driver creates multiple devices for those because it has no other
 > mechanism to distinguish them.

I want to ask further question about this.

Can we realize whether the PCM device for AC-3 stream (hw:0,0) works or 
not from the output of lsusb? The sound card has several outputs 
(headphone, line, S/PDIF) and I don't know only hw:0,1 connects to all 
of them or not.

 > Entires like these in ~/.asoundrc or /etc/asound.conf:
 >
 >    defaults.pcm.card 0
 >    defaults.pcm.device 1

But the device is connected by USB. The card ID differs depending on the 
user's system. If the other sound card is identified as "card 0", this 
setting is applied to it, not to the target device.

Can we write additional information to identify this sound card in these 
line?

 > I'd guess the driver could be changed to enumerate alternate settings
 > in two steps, first for PCM formats, then for others.

This is a better solution. But I have a little knowledgement about USB 
Audio Class and it's implementation to ALSA.
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Clemens Ladisch | 6 Jul 16:30 2013
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Re: [usb-audio] VIA/Audinst HUD-mx2: One of two PCM device is available for playback

Takashi Sakamoto wrote:
>> This device has multiple alternate settings for PCM and AC-3 playback.
>> The driver creates multiple devices for those because it has no other
>> mechanism to distinguish them.
>
> Can we realize whether the PCM device for AC-3 stream (hw:0,0) works
> or not from the output of lsusb?

If the device declares that it supports AC-3, it'd assume that this will
work (if the data actually is AC-3).

>>    defaults.pcm.card 0
>>    defaults.pcm.device 1
>
> The card ID differs depending on the user's system.

defaults.pcm.card "HUDmx2"

Regards,
Clemens

Gmane