[alsa-devel] multistream singlechanel DACs

Raymond Yau superquad.vortex2 at gmail.com
Fri Aug 24 03:55:39 CEST 2012

2012-8-24 上午1:10 於 "Rafal Powierski" <powierski at mediascore.de> 寫道:
> Developers,
> how to enable multiple playback streaming?:
> I am manipulating bios verb pin table, for special analog hardware, using
ALC886 and kubuntu / 64bit.

can you post the output of alsa-info.sh ?

> I need a number of separate stereo (only stereo) i/o's
> I have correctly configured inputs:
> 4. single stereo adc port-C 1Ah
> 5. single spdif input 1Fh
> I have configured 3 independent stereo outputs, but ALSA is joining them
into one pcmC1D0p device.
> 1.port-A,15h
> 2.port-E,1Bh
> 3.port-D,14h

how do you configure them as non multi channel pin complex ? different
association and zero sequence instead of same assosication and asscending
sequence for multi channel pin complex with color jacks.

> I have tried this on win7 and I got all associations as a separate

> in my kubuntu 12.4LTS I have only one playback device.

this is the multi channel out device with headphone using front channel

the major problem is pulseaudio does not support multi- streaming

the headphone playback volume control is the slave of virtual master
playback volume control.

> Mixer is showing even more then needed number of volume controls,
> But there is only one playback device.
> it seams, all 3 outputs are connected to single DAC.
> I have tried to buildup more input devices - this is working good.
> I can have up to 3 (pcmC1D0c, pcmC1D1c pcmC1D2c)

it is possible to use two or more ADCs for multi  channels capture similar
to the multi channels playback by assign same stream tag and  channel tag
to the three ADCs

> I can also have 2 outputs if I enable spdif-out.

the alc888s-vc seem has two independent digital output for spdif and hdmi

> But there is no separate DAC assignment  to separate devices resulting
> my  config.
> Is it possible to get independent DACs devices under ALSA?

you can use alt_analog_playback stream for independent headphone port-A
similar to those VIA codecs

the datasheet only mention 7.1 + 2 multi streaming using front and rear
audio panel

if it really work on other operating system, you may try to increase the
number of substreams of the alt_analog_playback and assign DACs to each
alt_analog_playback  substreams similar to the way which the driver assign
ADCs to the capture substreams

however you need to disable the multi channel analog  playback stream

> or else is no such configuration possible and I have to use single
multiple channel device?

the alternative is to use jackd

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