The setting audio_output_format forces
MPD to use one audio format for
all outputs. Doing that is usually not a good idea. The
values are the same as in format in the audio_output
section.
Sometimes, music needs to be resampled before it can be played; for example, CDs use a sample rate of 44,100 Hz while many cheap audio chips can only handle 48,000 Hz. Resampling reduces the quality and consumes a lot of CPU. There are different options, some of them optimized for high quality and others for low CPU usage, but you can't have both at the same time. Often, the resampler is the component that is responsible for most of MPD's CPU usage. Since MPD comes with high quality defaults, it may appear that MPD consumes more CPU than other software.
The following resamplers are available (if enabled at compile time):
libsamplerate a.k.a. Secret Rabbit Code (SRC).
libsoxr, the SoX Resampler library
internal: low CPU usage, but very poor quality. This is the fallback if MPD was compiled without an external resampler.
The setting samplerate_converter controls
how MPD shall resample music.
Possible values:
| Value | Description |
|---|---|
"internal"
| The internal resampler. Low CPU usage, but very poor quality. |
"soxr very high"
| Use libsoxr with "Very High Quality" setting. |
"soxr high" or
"soxr"
| Use libsoxr with "High Quality" setting. |
"soxr medium"
| Use libsoxr with "Medium Quality" setting. |
"soxr low"
| Use libsoxr with "Low Quality" setting. |
"soxr quick"
| Use libsoxr with "Quick" setting. |
"Best Sinc Interpolator" or
"0"
| libsamplerate: Band limited sinc interpolation, best quality, 97dB SNR, 96% BW. |
"Medium Sinc Interpolator" or
"1"
| libsamplerate: Band limited sinc interpolation, medium quality, 97dB SNR, 90% BW. |
"Fastest Sinc Interpolator" or
"2"
| libsamplerate: Band limited sinc interpolation, fastest, 97dB SNR, 80% BW. |
"ZOH Sinc Interpolator" or
"3"
| libsamplerate: Zero order hold interpolator, very fast, very poor quality with audible distortions. |
"Linear Interpolator" or
"4"
| libsamplerate: Linear interpolator, very fast, poor quality. |