One more post - I'll promise this is the last one. :)
On Fri, 11 Jul 2003, Carlo Wood wrote:
> That gives rather strange output:
But it's not stopping...? That's at least different behaviour...
> It doesn't feel right to read bytes when it says
> that there are no fragments/bytes available.
That's true, but as the read() is blocking it will wait
until there is data available before returning.
> Is the average bytes/second correct though?
[...]
> Number of channels: 1
> Sample rate: 22050
> and AFMT_S16_LE, what should it be? I am not so good
> at calculating things without knowing the unity of the
> 'rate' ;)... bits/s? Byte/s? (16-bit)Words/sec?
Hmm, not quite - you are reading 16bit samples at a rate of 22050 per sec,
so the data rate should be 22050*16/8=44100 bytes per second.
But the rate actually is 8000 (you can check this by catting
/proc/asound/card0/pcm0c/sub0/hw_params). In your code:
res = 22050;
if (ioctl(fd, SOUND_PCM_READ_RATE, 0xbfffdcfc) == -1)
{
perror("ioctl");
exit(1);
}
printf("Sample rate: %d\n", res);
... 'res' is always 22050 no matter what the device reports.
So with 8000, the date rate should be 16000 bytes/sec.
> Anyway, it seems too low or too high.
> When I add back the "if (info.fragments > 0)" test
> and decrease the naptime drastically, I get:
Try my other change to the test code - i.e. only sleep for
naptime when info.fragments is zero.
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