Alternate sample rates
A lot of common (desktop) hardware supports multiple sample rates. Interesting, among these, are 44100 Hz and 48000 Hz, since all common sample rates can be expressed as a simple multiple of one of these, which implies cheaper resampling, when it is required. Previous versions of PulseAudio only supported opening the device at a single sample rate, requiring all streams that did not match this rate to be resampled. We now support switching the device's sample rate dynamically at run time, allowing us to avoid resampling, or reduce resampling overhead. This should result in CPU and power savings on hardware that supports such switching (most Intel HDA-based devices at least).