Re: Duration of recorded file is longer than recording time using SoX

["George S. Williams" <ra@websterling.com>]

On 12/25/2019 4:23 PM, Jan Stary wrote:
>>>>> 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"?
GQRX is a SDR (Software Defined Radio) application, as was mentioned in 
the OP

pulseaudio is a AUDIO DEVICE DRIVER, 2 is the device being monitored
See, for example, 'sox -h'

> 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?
SoX is terrminated with Ctrl-C
>>>> 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?
The problem seems to be either with GQRX or Pulseaudio- probably not 
SoX. Using a different SDR and piping its output to SoX works fine, so 
I'm no longer working on this problem.

Thanks for the reply, but why the attitude?

George


>
> Jan
>
>
>
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