Comment 143 for bug 190754

Conn O Griofa (psyke83) wrote :

PulseAudio's resample-method in Ubuntu is currently set to "speex-float-3", which uses a high amount of CPU when a client uses a different sample rate than the server.

Here's an example: if you play a 48Khz mp3, it has to be downsampled PulseAudio's default rate of 44.1Khz. On my system, the pulseaudio process takes up a ridiculous amount of CPU in such a case, usually between 15-20% on my Pentium M 1.5Ghz system. On the other hand, playing a 44.1Khz mp3 causes pulseaudio to use around 5-10% CPU on average (as it uses the resample-method "copy", which is no resampling at all).

Unfortunately, PulseAudio cannot change sample rates dynamically (see http://www.pulseaudio.org/ticket/262 ), so we can mitigate this high CPU load by using a faster resampler. I propose that we use the "speex-fixed-0" resample-method, as it reduces pulseaudio's average CPU usage from ~15% to ~10% when resampling.

See Mandriva's bug report here: https://qa.mandriva.com/show_bug.cgi?id=36084
Their resolution to high CPU usage was to change the resample-method to "speex-fixed-0".