Re: [ecasound] Problems getting realtime recording.

From: Kai Vehmanen <kvehmanen@email-addr-hidden>
Date: Thu Jul 03 2008 - 00:11:12 EEST


On Tue, 1 Jul 2008, Avuton Olrich wrote:

> Running v2.6.25.8-rt7 (and other kernels I have tried) and recording
> with ecasound I'm getting messages like:
> warning! playback overrun - samples lost! Break was at least
> 1214667212122.58 ms long.

actually you've discovered a _very_ old (more than six years at least) bug
in the warning message (just in the message). The above should say "record
overrun". I actually update the whole message in the current devel tree

"WARNING: ALSA recording overrun, some audio samples were lost!"

... so there has been a too long break in process scheduling and some
recorded samples were lost. The reason is either:

  a) too little buffers in the audio driver/hw (try -z:intbuf)
  b) kernel scheduling issue
  c) bug in ALSA or the specific driver

> Could this be a false alarm?

I've afraid not. When the above is printed out, some samples where most
probably really lost in the recorded audio streams. The same message
should print out the duration of the break.

If you want ecasound to stop processing and exit when an xrun happens,
specify -z:xruns.

> I have also gotten the following error message (repeated many times):
> Unknown device state '3'

That suggests something fishy going on with the ALSA driver. State '3'
is an ALSA enum "SND_PCM_STATE_RUNNING", i.e. everything is ok. But what's
weird is that the above message from ecasound is printed when ALSA returns
an error when reading audio data, but the device state is not "XRUN"
(underrun has occured) nor "SUSPENDED". So it would suggest that something
has gone bad at the driver level.

> This one causes recording to stop, for sure.

Which would match with my hypothesis about things going bad on driver

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Received on Thu Jul 3 00:30:14 2008

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