Re: status of usb audio driver

[Takashi Iwai <tiwai@suse.de>]

At Thu, 13 Jun 2002 21:54:08 +0900,
Patrick Shirkey wrote:
> 
> Takashi Iwai wrote:
> > 
> > actually the endpoints of the first two pcm streams are identical.
> > is the sound only mono?
> 
> Yes it *was* just through output 2 or 4 on the card.
> 
> > on the description, it's defined as stereo streams.
> > so i guess quattro has two stereo streams, corresponding #0 (or #1)
> > and #2.
> > it seems that the stream #0 has only 16bit 44.1kHz at most, while the
> > stream #1 supports 16/24bit 48kHz (although 24bit-3bytes format is not
> > supported on alsa yet).
> > 
> 
> This card is supposed to be 24bit/96Khz. In windows it works like this:
> 
> 4 i/o channels(2 in, 2 out) at 16bit/48Khz or less
> 3 i/o channels(2 in, 1 out or 1 in, 2 out) at 24bit/48Khz or less
> 1 channel at 24bit/96Khz
 
interesting.  i don't find any mono channel on the descriptions.
well, more investigations are necessary.


> I understand why the 24 bit is not being registered, is that also the 
> probable reason why 96Khz is not being found?
 
yes, it's because 88.2 and 96kHz are supported only with 24bit
format.
i'll work on the extension of more formats, so that 24bit on usb can
work.

 
> > 
> > i've tested usb mic from Labtec, and it works.
> > so the problem is specific to the hardware, or multi-channels...
> > 
> 
> I just remembered that my mouse is a usb mouse too so that is not 
> unexpected.

too much bandwidth?


> > 
> > anyway, could you try the attached patch?
> > 
> 
> Excellent work. That has enabled stereo playback in hw:2,0 hw:2,1 and 
> hw:2,2.

good!

then it was a bug of linux usb core stuff.
well, we may call it a bug of hardware :)
the quattro has insuccessive alternate settings, jumping from 0 to 4.
and linux usb core implicitly assumes the successive numbers.

anyway i'll commit this version to cvs now.


> I am unsure about a couple of things though. hw:2,0 and hw 2,1 
> seem to be doing the same thing.

that's also a question to me :)
as written in my previous mail, hw:2,1 supports 24bit, while hw:2,0
doesn't.  perhaps this is only difference.


Takashi

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