FFMPEG

ffmpeg -i IN -ss 00:00:30.0 -t 00:03:00 -c copy OUT

Prendra 3 minutes du fichier en démarrant à 30 secondes

-c copy sans réencoder

ATTENTION : les idTags seront perdus

-c[:stream_specifier] codec (input/output,per-stream)

ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
encodes all video streams with libx264 and copies all audio streams.

ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:3 libvorbis OUTPUT
copy all the streams except the second video, which will be encoded with libx264, and the 3rd audio,
which will be encoded with libvorbis.

MP3DIRECTCUT

http://mpesch3.de1.cc/index.html