Re: [alsa-devel] trace PCM data from usb bus to alsa lib

At Wed, 17 Jun 2009 16:10:26 +0800, Zero Luo wrote:

Dear Takashi,      Data from usb dongle is 16K*16 bit PCM data.

And what is the format and channels you are using in alsa-lib? alsa-lib itself can convert formats and channels automatically if needed.

Takashi

2009/6/17, Takashi Iwai tiwai@suse.de:

At Wed, 17 Jun 2009 07:25:25 +0000 (UTC),
ZeroCluo wrote:
>
> Hi
>
>   I am trying to trace the Audio data from usb bus.
> in kernel:
> dump data in retire_capture_urb() ,found data format is like:
> AABB 0000 CCDD 0000 ;
>
> but in alsa library ,
> dump data in snd_pcm_mmap_begin(),the "0000" is cut,only "AABB CCDD",
>
> Do you know when and where those "0000" is cut?

Are you using the native format that the hardware runs?

Takashi