[alsa-devel] alsa-lib: snd_pcm_delay and friends do not account for a write being currently in progress

John Lindgren john.lindgren at tds.net
Thu Jun 3 18:16:03 CEST 2010

On Thu, 2010-06-03 at 16:48 +0200, Clemens Ladisch wrote:
> That applies to the kernel code.
> Most functions in alsa-lib must not be called at the same time on the
> same device handle.  (Don't ask me where this is documented.)

Do you have a problem with patches that improve the current situation?

> > Would it work to simply call snd_pcm_wait?
> Yes.  (I usually suggest poll because the code that writes audio data
> often wants to be informed of some other event.  If your writing loop
> doesn't need to be interrupted, snd_pcm_wait works just fine.)

It is permissible, then, to call snd_pcm_delay during a snd_pcm_wait

What would be the cleanest way to interrupt snd_pcm_wait when we need to
stop the stream?  Will snd_pcm_drop work?

John Lindgren

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