Comment 98 for bug 345627

Daniel,

The "src-linear" resampler (current setting in Jaunty) is really awful, too. It causes crackles for certain ranges in audio (e.g. explosions); by crackles I mean resampling artifacts, not stuttering or buffering problems. These crackles never occurred with ALSA's default dmix, and I mentioned some of my results regarding the different resamplers in the comments of bug #190754.

My understanding is that this is the rough "ranking" of resamplers, from best to worst (with CPU usage following the same trend, from high to low): src-sinc-best-quality, src-sinc-medium-quality, src-sinc-fastest, speex-float-{10-0}, speex-fixed-{10-0}, ffmpeg, src-zero-order-hold, src-linear, trivial.

As you can see, we're currently using the second-worst resampler. From personal testing, my conclusion was that speex-float-1 was the best resampler that balanced low CPU usage with audio quality (no distortion or crackles at certain ranges). For all the resamplers from speex-float-0 and below, crackles occured on both of my systems (using different codecs of snd-intel8x0).

I suggest if you have time (and find some appropriate audio samples), you test some of the resamplers to find the optimal default in PulseAudio.