The meaning of period in ALSA

Question

I\'m using ALSA for and audio application on Linux, I found great docs explain how to use it : 1 and this one. although I have some issues to understand this part of th

Answer 1

When the application tries to write samples into the buffer, an if the buffer is already full, the process goes to sleep. It gets woken up by the hardware through an interrupt; this interrupt is raised at the end of each period.

There should be at least two periods per buffer; otherwise, the buffer is already empty when a wakeup happens, which result in an underrun.

Increasing the number of periods (i.e., reducing the period size) increases the safety margin against underruns caused by scheduling or processing delays.

The latency is just proportional to the buffer size: when you completely fill the buffer, the last sample written is played by the hardware only after all the other samples have been played.