On Sun, 30 May 2004, Giuliano Pochini wrote:
> On Wed, 26 May 2004 09:52:06 +0200 (CEST)
> Jaroslav Kysela <[EMAIL PROTECTED]> wrote:
>
> > > > ALSA does not know about this. All period sizes must be equal.
> > >
> > > I thought about this again. Are you sure all periods must be aqual ?
> > > When I record or play something using unequal periods, sound is perfect.
> > > It means ALSA reads and writes the last (sometimes a lot) smaller period
> > > as well.
> >
> > The driver must not acknowledge the settled period with the midlevel and
> > application before the specified time. Of course, if you're running into
> > a rounding problem, you can acknowledge more periods at one time.
> > In other cases, it's not very practical to program hardware to use
> > different period sizes, because you need more interrupts for processing.
>
> My question was about your sentence: "All period sizes must be equal". Is it
> true ? It seems quite strange to me because ALSA passes a buffer size that
Yes, the time distance between period boundaries must be equal in longer
term. Of course, interrupt/hardware latencies might shift the interrupt
processing a few samples after.
> is not multiple than the period size almost always. This is not a problem in
I don't say that periods * period_size == buffer_size. It's another
special case.
> my case because the s-g list is generic enough to handle it.
Yes, that's right.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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