[pulseaudio-discuss] Weird data flow (not waveform)

David Henningsson launchpad.web at epost.diwic.se
Tue Jun 15 12:15:34 PDT 2010

On 2010-06-15 20:49, José Tomás Tocino García wrote:
> I think that's not the problem, because Gnuplot does not expect a
> exact format, it renders whatever it gets.
> The thing is, a usual waveform gets positive and negative values all
> the time. Sometimes that's what some DSP algorithms use to measure
> frequency, but given the stream has this weird representation, they do
> not work. That's what bugged me in first place, so I used gnuplot to
> visually check the waveform.
> Isn't is supposed to be a PCM waveform?

Yes it is. If your mic has a DC offset you might get only negative or
only positive levels though. What sample spec are you using in your call
to pa_simple_new? Perhaps you have to specify the exact format for
gnuplot, if it guesses wrong.

By the way, there are plenty of programs that do simple recording -
arecord, parecord, audacity etc should be able to do that as well.

// David

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