What is the relation between ALSA and PulseAudio sound architecture?

pulseaudio alsa

PulseAudio basically sits atop ALSA, and use it internally. ALSA is unable by itself to be used by multiple applications, so PulseAudio provides this functionality among others.

Summarized:

  • ALSA - dealing with the hardware, basically owning it
  • PulseAudio - a software proxy providing additional featues (mixing, equalizer) between your application and the ALSA/OSS subsystem

This diagram is from the Wikipedia page of PulseAudio:

PulseAudio operational flow chart

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