Re: [Jack-Devel] How can Jack run with less nperiods than ALSA?

So what is going on there? Is this running at 4 or 16 periods?

On 9 November 2013 19:04, Kaspar Bumke <[hidden]> wrote:
> right, so this output is what is confusing me:
>
> /usr/local/bin/jackd -dalsa -n 4
> jackd 0.124.0
> Copyright 2001-2009 Paul Davis, Stephane Letz, Jack O'Quinn, Torben
> Hohn and others.
> jackd comes with ABSOLUTELY NO WARRANTY
> This is free software, and you are welcome to redistribute it
> under certain conditions; see the file COPYING for details
>
> JACK compiled with System V SHM support.
> loading driver ..
> creating alsa driver ... hw:0|hw:0|1024|4|48000|0|0|nomon|swmeter|-|32bit
> [14020.281368] tlv320aic3x-codec 1-001b: ASoC: Not enforcing
> symmetric_rates due to race
> configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 4 periods
> ALSA: final selected sample format for capture: 32bit integer little-endian
> ALSA: use 16 periods for capture
> ALSA: final selected sample format for playback: 32bit integer little-endian
> ALSA: use 16 periods for playback
>
> On 9 November 2013 17:55, Paul Davis <[hidden]> wrote:
>>
>>
>>
>> On Fri, Nov 8, 2013 at 6:18 AM, Kaspar Bumke <[hidden]> wrote:
>>>
>>> Hey,
>>>
>>> this is a question that is bothering me as I try and understand the Jack
>>> architecture better.
>>>
>>> Say that ALSA is running at 48kHz 256samples with 4 periods. What happens
>>> when I start jack with 2 periods? Where do the additional interrupts come
>>> from?
>>
>>
>> quite a bit of confusion here, it seems. JACK will not general work
>> correctly when sharing a device. If it is sharing a device, then it is
>> ALSA's job to generate the timingm, and it will use one of several possible
>> timer sources.
>>
>> In general if JACK is using a particular PCM device, it is the *only* user
>> of that device, and ALSA is doing what JACK tells it to do.
>>

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