[PD] [OT] pacat / parec padding with zeros

[Nicolas Montgermont]

Hello all,

Sorry for this OT but nobody is answering in the pulseaudio IRC and
maybe some of you know about this problem.

Under Ubuntu 14.04, I'm using a software that has a pulseaudio output
and I use pacat to record directly the sound coming from pulseaudio like
this:
pacat --record --format=s16le --rate=48000 --channels=2
--file-format=wav --volume=32768 --latency-msec=100 -d
alsa_output.pci-0000_00_1b.0.analog-stereo.monitor &
sleep 2.5 && killall pacat

It is working well on the same machine with 12.04, but on 14.04 there is
a problem.

Some of the files are ~4 times bigger than expected. When I look at them
I see that sequences of zeros are randomly inserted in the file thus
increasing its size.
This phenomena is happening as a group : for a few minutes, recording
~50 files is fine, then for a long time, it is padded, then it can be
fine again...
Looking closer to the file, it seems that there is some relation to zero
crossings: the time where zeros are inserted seems to be close to zero
value of the wave data.

I've tried playing with format or piping to sox, the problem is still
happening.

As a workaround I tried to trim all the silences, but I didn't manage to
use the sox command for that:
$sox in.wav out4.wav silence 1 0.1 1% -1 0.1 1%
from : http://digitalcardboard.com/blog/2009/08/25/the-sox-of-silence/

Does anybody have an idea of what I can do to solve the recording problem?
Or if someone has a workaround to trim silence it will be really helpful!
best,
n

-- 
http://www.nimon.org

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