03.04.2015 00:36, Andrew Kelley wrote: > I discovered a curiosity: > > $ play ~/tmp/44100hz.wav > $ ./list_devices > playback device: 44100 Hz Built-in Audio Analog Stereo (default) > $ play ~/tmp/48000hz.wav > $ ./list_devices > playback device: 48000 Hz Built-in Audio Analog Stereo (default) > $ play ~/tmp/99999hz.wav > playback device: 44100 Hz Built-in Audio Analog Stereo (default) > > > In other words, PulseAudio changes the default sample rate of my > playback device when I open it with a different sample rate. But if I > open the playback device with a weird sample rate such as 99999Hz then > PulseAudio changes the default sample rate to 44100Hz. When I say > default sample rate, I mean when I query for the list of sinks with the > API and look at the sample_spec. > > I'm trying to understand this phenomenon. Can anyone shed some light on > this? For non-passthrough streams, PulseAudio always opens the sink either with the default or with alternate sample rate. These rates can be configured when loading module-alsa-sink, and there are also global defaults in /etc/pulse/daemon.conf. The defaults are 44100 and 48000 Hz. The code that chooses whether to use the default or alternate sample rate is in the pa_sink_update_rate() function, in src/pulsecore/sink.c. -- Alexander E. Patrakov
