[alsa-devel] snd_pcm_hw_params_set_buffer_time_near: invalid argument
jyavenard at gmail.com
Wed Mar 9 13:23:41 CET 2011
On Wednesday, 9 March 2011, Raymond Yau <superquad.vortex2 at gmail.com> wrote:
> hda-intel.c only allocate 64Kbytes
> /* buffer pre-allocation */
> snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
> 1024 * 64, 32 * 1024 * 1024);
> user or distribution need to change "prealloc" from 64 to a higher value for
> getting 500ms buffer
> echo 1024 > /proc/asound/Intel/pcm0p/sub0/prealloc
It seems you misunderstood my first message.
For a start, the default memory allocated to alsa in ubuntu is 4096kB.
so the amount of ram isn't the problem.
Setting a buffer of
400ms: not ok (invalid argument)
Why would 400ms gives invalid argument, when 500ms doesn't nor 300.
Memory available is obviously not the issue.
If only 64kB is allocated, requesting 200ms gives you 200ms
300ms -> 300ms
400ms -> invalid argument
500ms -> 371ms
600ms -> 371ms
You would assume that requesting 400ms would work or return what can
fit in what has been pre-allocated.
More information about the Alsa-devel