Re: [ecasound] Bug report: strange crash

From: Kai Vehmanen <kvehmanen@email-addr-hidden>
Date: Thu Apr 12 2012 - 18:49:04 EEST


On Wed, 11 Apr 2012, S. Massy wrote:

> - Implementing stop/replace_effect_logic/start:
> It no longer crashes but is slow even for one effect, and can take
> upwards of ten seconds to bypass or restore a whole chain of effects.
> A random amount of audio gets chopped off.

yes, I'm afraid this is expected. The stop/start procedure is slow (a lot
of work is done before and after stopping).

> - Implementing stop-sync/replace_effect_logic/start:
> No crash, bypassing one effect (IOW cop-remove/cop-add) is pretty
> instantaneous, but bypassing several can take up to two seconds, which
> is long but much less than the previous instance. When bypassing one
> effect, there seems to be no obvious audio lost, but a random amount
> of audio gets chopped off when bypassing several effects in one go.

Yes, this will help as you can reduce number of stop-starts (do many
changes in one go).

> - Current method stop/sleep/replace_effect_logic/sleep/start with
> ecasound 2.8.1:
> We sleep a total of 0.3 seconds, 0.2 between stopping and replacing
> the effects. No audio lost, no significant delay, no matter how many
> effects are being replaced.

But I fear this is just not reliable. The 0.3/0.2 values depend on setup
complexity, disk i/o speed (compared to amount of bandwidth needed by the
setup), CPU speed, system load. So it'll be impossible to pick values that
are reliable for everybody. :(

In the end, I think the sane way forward is for me to add cop-bypass to
the next ecasound version. Considering the overall effort, adding
cop-bypass is a lot less work than doing complicated optimizations to the
stop-start logic.

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Received on Thu Apr 12 20:15:01 2012

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