Re: [Jack-Devel] ALSA PCM multi plugin and xruns

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DateSun, 09 Dec 2012 10:45:35 +0000
From John Rigg <[hidden] at jrigg dot co dot uk>
ToDevin Anderson <[hidden] at gmail dot com>
CcJack devel <[hidden] at lists dot jackaudio dot org>
In-Reply-ToDevin Anderson [Jack-Devel] ALSA PCM multi plugin and xruns
Follow-UpStéphane Letz Re: [Jack-Devel] ALSA PCM multi plugin and xruns
Follow-UpDevin Anderson Re: [Jack-Devel] ALSA PCM multi plugin and xruns
On Sat, Dec 08, 2012 at 03:38:44AM -0800, Devin Anderson wrote:
> IIUC, the 'xruns' are generated because there *is* data available to
> be read, but there *isn't* enough data, which means 0 is returned,
> which incorrectly indicates that an xrun happened.  The exception is
> when both `capture_avail` and `playback_avail` are both set to 0.
> Perhaps userspace hasn't been told about new samples in the kernel
> ringbuffer.
> 
> I don't know whether this is a bug in the ALSA multi plugin or in
> JACK.  I assume the problem is the multi plugin, as
> `snd_pcm_hw_params_set_period_size` is called to constrain the period
> size to one value, but I don't have enough of an understand of ALSA to
> know for sure.  I'm hoping that someone on this list with a better
> understanding of ALSA magic will be able to answer that question for
> me.

This has been annoying me ever since I started using multiple
ice1712 cards nearly 7 years ago. I never had the time to look
into the cause. Thanks for investigating this.

John
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