[pulseaudio-discuss] Intercepting PulseAudio sound for EQ display?

Knut-Håvard Aksnes kna at tirsdagsklubben.nu
Thu Oct 23 00:42:19 PDT 2008

Josh Lehan wrote:
> Hello.  I have a question about intercepting PulseAudio-generated sound.
> I'd like to make a display for the sound buffer that is currently 
> playing in realtime, either an oscilloscope or an EQ.
> Is there an API within PulseAudio to do this?
> I looked at the monitor sample code for pavumeter, but it seems geared 
> towards just getting the overall volume level of the current buffer, and 
> not the actual sample data.
> I'd love a call to "sniff" the sample data fairly late in the output 
> process, after it has been mixed from all sources, just before it is 
> sent to the sound hardware.  Does such a thing exist?
Sure: Use the monitor interfaces. Each sink has associated with it a 
monitor source interface where you can listen to the stream being sent. 
To find it just add .monitor to the name of the source interface. The 
asynchronous API have calls to do this and lots of other useful tasks.

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