[linux-audio-user] low latency 2.4 help - needed

Jack O'Quin joq at io.com
Mon Mar 7 12:03:50 EST 2005


> Jack O'Quin wrote:
>> I suspect your USB device will become a latency bottleneck before
>> these kernels will, but only experimenting on your own system will
>> tell you for sure.

Atte André Jensen <atte.jensen at gmail.com> writes:
> Is there an inherent minimum latency for USB soundcards?

I have no USB sound card.  Perhaps someone else can answer that
question.

There *are* reported latency problems with USB, ALSA and JACK due to
isochronous USB data transfers and JACK's need for a constant power of
two buffer size.  IIUC, USB sends a block every 1ms.  With some sample
rates this does not result in a constant number of samples in every
block.  Progress has been made with certain specific devices (usx2y),
but I believe the general problem still remains.

These issues seem to become more intrusive at lower latencies.  But, I
really don't know what the limits are for your device.
-- 
  joq




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