Monitoring Audio Levels with PulseAudio

I'm working on driving an analog VU meter from my Raspberry Pi using whatever audio is going out the Pi's sound outputs. The de facto Linux sound system, PulseAudio, allows any sound output (or "sink" in PulseAudio's nonclementure) to be monitored. In PulseAudio land, each sink has a corresponding "source" called the monitor source which can be read just like any other other PulseAudio input such as a microphone. In fact, to help with volume meter style applications, PulseAudio even allows you to ask for peak level measurements, which means you can sample the monitor sink at a low frequency, with low CPU utilisation, but still produce a useful volume display. When this feature is used, each sample read indicates the peak level since the last sample.

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posted: Sun, 10 Feb 2013 22:05 | permalink | comments