[linux-audio-dev] pd/k_jack-ish soft-mode patch for jack (was: k_jack v0.0.0.5 and Mammut v0.15)

[Kai Vehmanen]

On Fri, 24 Jan 2003, Kjetil S. Matheussen wrote:

>> Yup, replace the set_stop_mode call with:
>> snd_pcm_sw_params_set_stop_threshold(handle, sw_params, XXX);
> I'm not able to make that work. Just gets a message about stock audio,
> no matter how big buffer it is. But thats not important.

Hmm, what's the exact error you get? One thing that will cause you trouble
is that audio playback will stop after the first xrun. You have to restart
the stream (stop-prepare-start) to recover from an xrun. This is also the
source of the longer audible breaks that occur with current JACK's ALSA
driver when xruns occur.

>> The difference is definitely notable. I've just patched jackd to ignore
>> all xruns the way pd does, and yup, I can do all kinds of stuff as a
>> normal user (with ./jackd -p 64 -n 27). I'm currently running
> Thats very nice. How about an option for jack to ignore xruns then?

True, I just posted a patch that does this to jackit-devel. So, so, as I 
said, competition is a good thing! ;D So thanks for releasing k_jack
and helping with the debugging/tracing work.

> And, are you absolutely sure its not a bug in alsa, reporting to many
> xruns? :)

This is very unlikely. The code in alsa-kernel/driver that handles this 
logic is _very_ robust. I haven't done much driver work, but I've still 
gone through those functions at least a hundred times, and I bet many 
other developers have done the same. The common PCM subsystem used by all 
ALSA low-level drivers is really high-quality code. The fact that all 
drivers can benefit from this common code library is IMHO one of the 
biggest benefits ALSA brings!

-- 
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