On Sun, Feb 29, 2004 at 01:31:01PM +0100, Jaroslav Kysela wrote:
> On Sun, 29 Feb 2004, Russell King wrote:
> > Could someone enlighten me about the way alsa-lib / alsa-driver are
> > supposed to work when using mmap mode please? I'm looking at the 1.0.2
> > code, along with madplay and Linux 2.6.4-rc1.
> >
> > madplay sets the start_threshold to the size of the buffer, and min_avail
> > to one period size - in much the same way as the alsa-lib test/pcm.c
> > program.
>
> We know about this problem. The start_threshold must be equal or less than
> (buffer_size / avail_min) * avail_min in this case.
I think it's a little more complex than that. In my case,
buffer_size = 16384, avail_min = 256, so:
(buffer_size / avail_min) * avail_min = 16384
which is what was being programmed anyway. However,
(int(buffer_size / avail_min) - 1) * avail_min = 16128
would make more sense. Do you agree?
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
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