Convert audio sample rate
audio
// what it does
Changes the audio sample rate with -ar: 44100 resamples to 44.1 kHz (CD rate) and 48000 to 48 kHz (video/broadcast rate). ffmpeg's swresample handles the conversion, re-encoding to the default codec for the output extension. Use it to match a target device or to reconcile tracks before muxing them together.
// shell
$ ffmpeg -i audio.mp3 -ar 44100 output.mp3$ ffmpeg -i audio.mp3 -ar 48000 output.mp3// gotcha
-ar has no effect with -c:a copy: a stream copy can't resample, so ffmpeg silently ignores the -ar (no error, no warning) and keeps the original rate — easy to miss. Let it re-encode (as here, no -c:a copy) so the resample actually happens.