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* [USB UAC2] How to route pcm stream for UAC2 virtual sound card for lowest latency?
@ 2015-03-10  8:27 Xuebing Wang
  2015-03-10  8:30 ` Clemens Ladisch
  0 siblings, 1 reply; 2+ messages in thread
From: Xuebing Wang @ 2015-03-10  8:27 UTC (permalink / raw)
  To: alsa-devel, richard Jiang, niranjan Patil

Hi Community,

I am developing a commercial product based on Freescale iMX6SL + UAC2.

I can get UAC2 working for below command. 'hw:1,0' is the virtual sound 
card. 'hw:0,0' is the physical sound card.
export RATE=44100; arecord -D hw:1,0 -c 2 -r $RATE -f S16_LE | aplay -c 
2 -r $RATE -f S16_LE &

Any suggestions on what is the best way to get PCM stream from UAC2 
virtual sound card and feed to the physical sound card, for the lowest 
latency purpose?

Thanks.

-- 
Xuebing

^ permalink raw reply	[flat|nested] 2+ messages in thread
* Re: [USB UAC2] How to route pcm stream for UAC2 virtual sound card for lowest latency?
  2015-03-10  8:27 [USB UAC2] How to route pcm stream for UAC2 virtual sound card for lowest latency? Xuebing Wang
@ 2015-03-10  8:30 ` Clemens Ladisch
  0 siblings, 0 replies; 2+ messages in thread
From: Clemens Ladisch @ 2015-03-10  8:30 UTC (permalink / raw)
  To: Xuebing Wang, alsa-devel, richard Jiang, niranjan Patil

Xuebing Wang wrote:
> I am developing a commercial product based on Freescale iMX6SL + UAC2.
>
> I can get UAC2 working for below command. 'hw:1,0' is the virtual sound card. 'hw:0,0' is the physical sound card.
> export RATE=44100; arecord -D hw:1,0 -c 2 -r $RATE -f S16_LE | aplay -c 2 -r $RATE -f S16_LE &
>
> Any suggestions on what is the best way to get PCM stream from UAC2
> virtual sound card and feed to the physical sound card?

This will not work unless the clocks of the virtual sound card (i.e.,
the USB bus clock) and the clock of the actual sound device are
synchronized.

Otherwise, you have to write your own UAC2 driver.


Regards,
Clemens

^ permalink raw reply	[flat|nested] 2+ messages in thread
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2015-03-10  8:27 [USB UAC2] How to route pcm stream for UAC2 virtual sound card for lowest latency? Xuebing Wang
2015-03-10  8:30 ` Clemens Ladisch

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