[alsa-devel] dsnoop issues
tiwai at suse.de
Fri Apr 27 14:37:39 CEST 2007
At Fri, 27 Apr 2007 13:27:00 +0100,
Gordon Miller wrote:
> All my snd_pcm_readi calls return too few frames. Also when I switch to
> stereo, the sound is muted. I cannot change this by adjusting period &
> buffer sizes. dsnoop is enabled by default. The documentation for
> snd_pcm_readi says that the only way that the frame count can be short
> is because of a signal or xrun. Well this clearly isn't the case.
Actually, the documentation is wrong, IMO. The typical behavior of
read syscall is that it returns a value actually read by that call.
It doesn't guarantee whether the requested size is filled, and can be
shorter than requested. As snd_pcm_readi() emulates the read syscall,
it should behave in that way.
The blocking mode means that the function waits until the threshold
(watermark) condition is fulfilled.
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