SongPlayer and ANR seem to give quick and precise lengths for tracks, what I tried just. They don't write anything anywhere as far as I see. Maybe they use some simplier calculation which seems to be enough still.

Amplifier and AmigaAmp give lenghts totally off.

MPlayer is quick too and seems to be accurate.

[ Edited by jPV 21.12.2013 - 21:36 ]