[alsa-devel] Buffer size for ALSA USB PCM audio

[James Stone]

On Wed, Aug 28, 2013 at 7:46 PM, Alan Stern <stern at rowland.harvard.edu> wrote:
> On Wed, 28 Aug 2013, Clemens Ladisch wrote:
>
>> Sorry, what I said applies more to explicit sync endpoints.  When using
>> implicit sync, a playback URB is submitted for each completed capture
>> URB, with the number of samples per packet identical to the
>> corresponding capture packet, so the parameters must be identical.
>
> Got it.  Below is an updated patch.
>
> James, the problem you encountered was most likely a result of the
> faulty treatment of capture endpoints that Clemens pointed out.  It was
> quite obvious in the usbmon traces that the unpatched driver used 8
> packets per URB whereas the patched driver used 22.  This updated patch
> should fix that problem.
>

Works fine. With this, it is possible to get clear playback at 64
frames/period too. With vanilla 3.10.9, there was some glitchy
distortion to the sound at that latency, so this seems to be an
improvement.

James