Jaroslav Kysela wrote:
> On Mon, 22 Mar 2004, James Courtier-Dutton wrote:
>
> > My current tests were not using the resampler. i.e. app using 48k, sound
> > card using 48k. I will try some tests that would use the resampler.
>
> Then I need more info how I can reproduce the bug.
The following test program shows strange behaviour:
// ---------- bite off here ----------------------------------------
#include <alsa/asoundlib.h>
#define CHECK(command) do { \
err = (command); \
if (err < 0) { \
printf("%s failed: %s\n", #command, snd_strerror(err)); \
return 1; \
} \
} while (0)
int main(int argc, char *argv[])
{
snd_pcm_t *pcm;
snd_pcm_hw_params_t *hw_params;
snd_pcm_sw_params_t *sw_params;
int err;
static char silence[12000 * 2 * 2];
if (argc < 2) return 1;
CHECK(snd_pcm_open(&pcm, argv[1], SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK));
snd_pcm_hw_params_alloca(&hw_params);
CHECK(snd_pcm_hw_params_any(pcm, hw_params));
CHECK(snd_pcm_hw_params_set_access(pcm, hw_params,
SND_PCM_ACCESS_RW_INTERLEAVED));
CHECK(snd_pcm_hw_params_set_format(pcm, hw_params, SND_PCM_FORMAT_S16));
CHECK(snd_pcm_hw_params_set_channels(pcm, hw_params, 2));
CHECK(snd_pcm_hw_params_set_rate(pcm, hw_params, 48000, 0));
CHECK(snd_pcm_hw_params_set_buffer_size(pcm, hw_params, 12000));
CHECK(snd_pcm_hw_params_set_period_size(pcm, hw_params, 6000, 0));
CHECK(snd_pcm_hw_params(pcm, hw_params));
snd_pcm_sw_params_alloca(&sw_params);
CHECK(snd_pcm_sw_params_current(pcm, sw_params));
CHECK(snd_pcm_sw_params_set_start_threshold(pcm, sw_params, 12000));
CHECK(snd_pcm_sw_params_set_avail_min(pcm, sw_params, 6000));
CHECK(snd_pcm_sw_params(pcm, sw_params));
for (;;) {
CHECK(snd_pcm_wait(pcm, 2000));
if (err == 0)
printf("timeout!\n");
err = snd_pcm_writei(pcm, silence, 12000);
if (err >= 0)
printf("%d frames written\n", err);
else if (err == -EAGAIN)
printf("pcm not ready!\n");
else
CHECK(err);
}
}
// ---------- bite off here ----------------------------------------
With an AC'97 device:
$ ./waittest hw:0
12000 frames written
6000 frames written
6000 frames written
6000 frames written
6000 frames written
...
$ ./waittest dmix:hw:0
timeout!
12000 frames written
pcm is not ready!
6000 frames written
6000 frames written
6000 frames written
6000 frames written
...
When running with dmix, the first call to snd_pcm_wait() times out
although the pcm is ready (it seems the hardware pcm is still stopped
and doesn't generate interrupts), and the second call to
snd_pcm_wait() returns 1 although the pcm is not yet ready.
Regards,
Clemens
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