[alsa-devel] defaults.pcm.minperiodtime 5000

Jaroslav Kysela perex at perex.cz
Thu Sep 2 10:21:25 CEST 2010

On Thu, 2 Sep 2010, Raymond Yau wrote:

> 2010/8/12 Jaroslav Kysela <perex at perex.cz>
>> On Thu, 12 Aug 2010, Raymond Yau wrote:
>>> BTW , it seem this patch change the behaviour of alsa-lib too.
>>> all sound cards will now have a minperiodtime 5000
>> Nope. If application settles the period time/size, the behaviour is
>> unchanged (see the min/max condition). We just want to limit the period
>> sizes for applications which do not know what they are doing and allow any
>> period time/sizes. It's better to limit the minimal period size to avoid
>> generation of many interrupts per second in this case.
> This mean that if application did not set sample rate by using
> snd_pcm_hw_params_set_rate_near() , alsa-lib will select default rate
> (minimum rate of 1 Hz for alsa-pulse plugin )
>    err = snd_pcm_ioplug_set_param_minmax(io, SND_PCM_IOPLUG_HW_RATE,
>                          1, PA_RATE_MAX);
> This kind of application cause PA server aborted immediately in Fedora 10
> and Fedora 13

The alsa-pulse plugin should provide valid accepted rate range. It's not 
issue in alsa-lib. I would set the low limit to something like 5000Hz.


Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.

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