[alsa-devel] Split a 7.1 device into 4 stereo devices
Hello,
I have a 7.1 sound device and speaker-test -c8 can output on each speaker. But what I would like to do is using it as 4 stereo devices so I could play different sounds on each of them.
Ideally I would like to avoid dmix and friends to be able to have gapless and bit-perfect output.
On IRC "debianuser" said it is possible with hdajackretask to make it appear as 4 different hw devices in "aplay -l" but we didn't succeed doing that. Anyone knows what configuration is needed for that?
Here is my setting: http://www.alsa-project.org/db/?f=bf0744873d5e6d42d3adc0076c5f66189e9191b7
Regards, Xavier Claessens.
08.07.2014 18:18, Xavier Claessens kirjoitti:
Hello,
I have a 7.1 sound device and speaker-test -c8 can output on each speaker. But what I would like to do is using it as 4 stereo devices so I could play different sounds on each of them.
Ideally I would like to avoid dmix and friends to be able to have gapless and bit-perfect output.
On IRC "debianuser" said it is possible with hdajackretask to make it appear as 4 different hw devices in "aplay -l" but we didn't succeed doing that. Anyone knows what configuration is needed for that?
Here is my setting: http://www.alsa-project.org/db/?f=bf0744873d5e6d42d3adc0076c5f66189e9191b7
I guess this really belongs on alsa-user@ list, but oh well...
No idea about hdajackretask, but you can use e.g. "dshare" plugin.
Simple example below with 6ch split to three stereo devices, see documentation/Google for more information on options. You don't see the result in "aplay -l" but in "aplay -L".
pcm_slave.shared_dev { pcm "hw:CARD=PCH,DEV=7" channels 6 rate 48000 }
pcm.kas { type dshare ipc_key 119922141 slave shared_dev bindings { 0 0 1 1 } hint.description "Channels 0 and 1" }
pcm.mo { type dshare ipc_key 119922141 slave shared_dev bindings { 0 2 1 3 } hint.description "Channels 2 and 3" }
pcm.foobar { type dshare ipc_key 119922141 slave shared_dev bindings { 0 4 1 5 } hint.description "Channels 4 and 5" }
I have a 7.1 sound device and speaker-test -c8 can output on each speaker. But what I would like to do is using it as 4 stereo devices so I could play different sounds on each of them.
Ideally I would like to avoid dmix and friends to be able to have gapless and bit-perfect output.
On IRC "debianuser" said it is possible with hdajackretask to make it appear as 4 different hw devices in "aplay -l" but we didn't succeed doing that. Anyone knows what configuration is needed for that?
Here is my setting: http://www.alsa-project.org/db/?f=bf0744873d5e6d42d3adc0076c5f66189e9191b7
The easy way is to use jackd and alsa jack plugin
If you really need need four stereo devices, you need to customized snd_hda multiout_analog_open, snd_hda multiout_analog_prepare and snd_hda multiout_analog_cleanup similar to those alt_analog_capture_xxx function to use substream->number to provide four stereo devices
static const struct hda_pcm_stream pcm_analog_playback = { .substreams = 4, .channels_min = 2, .channels_max = 2, /* NID is set in build_pcms */ .ops = { .open = playback_pcm_open, .close = playback_pcm_close, .prepare = playback_pcm_prepare, .cleanup = playback_pcm_cleanup }, };
Since only those four retaskable jacks support HP, you may need to use input jacks if you want four headphones instead of four line out jackd
participants (3)
-
Anssi Hannula -
Raymond Yau -
Xavier Claessens