Re: [PATCH] sound/usb: Relax urb data alignment restriciton for HVR-950Q only

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On Fri, Dec 4, 2009 at 5:15 PM, John S Gruber <johnsgruber@xxxxxxxxx> wrote:
> Addressing audio quality problem.
>
> In sound/usb/usbaudio.c, for the Hauppage HVR-950Q only, change
> retire_capture_urb to copy the entire byte stream while still counting
> entire audio frames. urbs unaligned on channel sample boundaries are
> still truncated to the next lowest stride (audio slot) size to try to
> retain channel alignment in cases of data loss over usb.
>
> With the HVR950Q the left and right channel samples can be split between
> two different urbs. Throwing away extra channel samples causes a sound
> quality problem for stereo streams as the left and right channels are
> swapped repeatedly.
<snip>

Hello John,

Thanks for taking the time to dig into this.  I will try to review
your patch this weekend (in conjunction with the spec).

It's worth noting that there are actually nine different USB IDs that
would need this change (see au0828-cards.c), so it might be nice to
see if we can figure out a way for the au0828 driver to tell the
usbaudio driver about the quirk without relying on embedding USB ids
in the usbaudio driver.

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com
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