Re: [ecasound] ecasound+jack silent stop, silent data loss

From: Kai Vehmanen <kvehmanen@email-addr-hidden>
Date: Mon Mar 05 2007 - 00:14:03 EET


sorry for the (probably too) late response.

On Wed, 6 Dec 2006, Paul Knowles wrote:

>>> first thing that comes to my mind is a glitch in JACK
>>> transport support. There're some messages about seeking in
>>> the middle of recording, and this shouldn't be
>>> happening. Could you retry the tests with adding the option
>>> "-G:jack,eca,notransport"...?
>> This seems to have done the trick. At least I have now 12
>> hours of uninterrupted recording. The analysis for phase
>> jumps (lost samples) is currently underway.
> Nope, spoke too soon. After analysis, the data loss is
> still there, It seems to be only one sample at most, not a
> whole buffer. With the notransport option, ecasound just
> doesn't tell me about it.

You could try recording directly with ecasound+ALSA, i.e. without JACK. It
shouldn't make any difference, but you'd have one less moving part in the
puzzle. Missing a single sample does suggest a hardware/driver level
problem though.

> I did isolate a problem with the word clock: while in use,
> occassionally the sound cards would drop the PLL coherence
> momentarily. I could not correlate that to the loss of
> data, but when the PLL problem was made worse, there was no
> increase in (supposedly lost) sample corruption, so I don't
> think that the word clock is the problem there.
> Any hints on how to make ecasound exit when this seek event
> occurs?

I'm afraid this is a similar hw/driver level issue that is not
escalated/signaled to application layer (i.e. to apps using
alsa-lib/libasound). Recording directly from ALSA, and with '-z:xruns'
ecasound option, might be worth a try though.

  links, my public keys, etc at
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Received on Mon Mar 5 00:15:03 2007

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