On Sun, 29 Feb 2004, Russell King wrote:
> Hi,
>
> 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. The avail_min
specifies the minimal transfer count (for optimization) so the
start_threshold - in this case - violates the read/write policy. The new
code in alsa-lib does not allow to install this "broken" sw_params
configuration, so application developers can detect this mistake.
Also, alsa-lib/test/pcm.c code was fixed to follow this specification
(I am sorry - it was my mistake). This fix will be available in 1.0.3
release.
So, the fault is on the application side.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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