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

José Tomás Tocino García theom3ga at gmail.com
Wed Jun 16 05:05:08 PDT 2010

I finally got it. Looks like, when I was parsing and/or dumping the
stream to a file, the stream operator << does not natively accept the
types defined in stdint like int16_t. Once I placed a cast (int) it
worked flawlessly :)

2010/6/15 David Henningsson <launchpad.web at epost.diwic.se>:
> 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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José Tomás Tocino García

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