[alsa-devel] Buffer size for ALSA USB PCM audio
zonque at gmail.com
Tue Aug 13 23:34:15 CEST 2013
On 13.08.2013 23:06, Alan Stern wrote:
> On Mon, 12 Aug 2013, Alan Stern wrote:
>> On Mon, 12 Aug 2013, Takashi Iwai wrote:
>>> So... Clemens, Daniel, Eldad, could you guys review the latest version
>>> of Alan's patch? I'd love to sort this out for 3.12.
>> Here's a revised version of the patch (still untested). The difference
>> is that this version tries always to keep a period's worth of bytes in
>> the USB hardware queue. This will provide better protection against
>> underruns when the period is larger than the queue's minimum
> After more thought, I decided that patch does too much. It's not
> necessary to keep track of the number of packets. Instead, the driver
> should always try to keep as much data in the USB hardware queue as it
> is allowed to.
> In other words, there should be enough URBs so that an entire ALSA
> buffer can be queued at any time, subject only to the limit on the
> maximum number of URBs and packets. It doesn't make sense to allocate
> just enough URBs to cover a single period.
> Does this seem reasonable?
I think so, yes. But I'd like to comment on the actual patch, and also
give it a try first of course. It took me some days to gather my setup
again, but if you send a revised version, I hope to be able to test it
in the next days.
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