|The SoX Resampler library libsoxr performs fast, high-quality one-dimensional sample rate conversion. Audacity started using libsoxr from version 2.0.3 onwards.
Four SoX Resampler quality levels are available for constant-rate resampling in Audacity; which one to use in different circumstances may be selected in the Preferences/Quality menu. Note that the names assigned to these levels differ from those used by the 'sox' command-line utility; equivalent names are shown in the following table:
|Best Quality||Very high|
See the 'rate' effect in the SoX manual for details (frequency response, etc.) of each of these quality levels.
For variable-rate resampling, libsoxr uses a single, dedicated quality level; this is selected automatically by Audacity when performing a task that requires it.
For comparison purposes, the following table attempts to place in order of increasing quality, current resampling qualities (with libsoxr), and those with resamplers available in previous/other configurations of Audacity:
|Fast Sinc Interpolation||-/14|
|High-quality Sinc Interpolation||-/15|
|Medium Quality||Fastest Sinc Interpolator||-/16|
|High Quality||Medium Sinc Interpolator||-/20|
|Best Sinc Interpolator||-/24|