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From: Jan Stary <hans@stare.cz>
To: sox-users@lists.sourceforge.net
Subject: Re: Duration of recorded file is longer than recording time using SoX
Date: Wed, 25 Dec 2019 22:23:34 +0100
Message-ID: <20191225212334.GA64006@www.stare.cz> (raw)
In-Reply-To: <a8e3d61914d42524ccce7aee2f6def13@wingsandbeaks.org.uk>

> > > > I'm using SoX on Centos 7 to record the audio output from GQRX, a SDR
> > > > application. I've selected Monitor of Built-in Audio Analog Stereo
> > > > from the Recording Tab of the Pulseaudio Volume Control. I'm
> > > > trying to
> > > > save a .wav file with a sample rate of 6k. I'm using the command
> > > > 
> > > > |sox -t pulseaudio 2 --rate 6k --channels 1 test.wav |
> > > Does the presence of the 'pipe' character before "sox" mean that audio
> > > was being generated by a previous command?
> > The command is run by itself- the pipe characters are a consequence of
> > copying and pasting that I didn't catch.

OK, sou you start

	sox -t pulseaudio 2 --rate 6k --channels 1 test.wav

at a terminal, and then start GQRX (whatever that is) to produce its
output, and have PulseAudio (the system audio framwork) monitor
the GQRX output as a recording. So that's what SoX gets. Right?

But that is not a valid SoX command line. In SoX SYNOPSIS parlance,
what is the "infile"? And what is "pulseaudio 2"? The "-t pulseaudio"
specifies the type (-t); what is the "2"?

Can you please post the output of your actual command line
with sox -V3 (for verbosity)?

Also, a command line like that will not stop recording its input
just because the other side has stopped producing output
(as opposed to reading a file as input). So how exactly
is the above SoX process terminated?

> > > In your "too long" wave file, does it start with 1h 6m of something
> > > else, or end with 1h 6m of something else?  Or what?
> > 
> > The wave file contains what was recorded, nothing extra. It is
> > 'stretched' to the longer duration.

How can it "contain what was recorded, nothing extra"
and at the same time be of different length? Is it the
rate change? That is, are you recording a 6kHz channel
at the specified rate of 6kHz?

Jan



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Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-16  2:39 George S. Williams
2019-12-16 16:14 ` Jeremy Nicoll - ml sox users
     [not found]   ` <f1382121-d632-9252-17a8-e7baed8913f2@websterling.com>
2019-12-16 20:53     ` Jeremy Nicoll - ml sox users
2019-12-25 21:23       ` Jan Stary [this message]
2019-12-26  1:02         ` George S. Williams
2019-12-28 15:52           ` Jan Stary

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