[alsa-devel] [ecasound] Garbage at end of playback: ecasound or alsa broken?

Knut Petersen Knut_Petersen at t-online.de
Sat Jul 20 14:02:34 CEST 2013

On 20.07.2013 11:57, Julien Claassen wrote:
> Hello Knut!
>     No idea yet, who's to blame. but have you tried repeating the experiment
> with another tool. You can use audacity, so you can use the GUI.

Audacity is even more broken. That´s true for the version from opensuse (2.03),
and it´s true for the current development code,

If I mark that 1s of audio described in the original post, a lot of audio is missing at the
beginning and a bit of audio is missing at end. In total only about 460 msec of audio
is captured, 540 msec is lost.

Audacity currently does not playback correctly  with non-memory-mapped alsa devices.
But that´s another story ;-(

> There are other recording applications. Or you might even try with the alsa utilities
> aplay and arecord. this will require two console or terminals.

If I put

     arecord -f cd -D hw:0,0 -d 2 testarec.wav  &
     aplay testin.wav -D hw:0,0

into a script I get a perfect recording: 47 msec silence, exactly 1s of audio data,
silence up to the end of the file. Well, that result seems to indicate that I found an
ecasound bug. Unless it´s some alsa code unused by aplay ;-)

>   You might also try the same experiment with JACK, if you're not averse to it.

In the best case that could only mask the bug.

>     I did digitise a few tapes and prelistened to the volume and audio quality.
> So it's not a problem in general.
Half a second silence at the end of the audio masks the bug. Because of that I agree that
it´s not a general problem, most people will never notice it. But it´s still a bug.


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