Why is the apple m4a is so large?

[Dellu]

I am trying to convert my flac files to apple's AAC format.

I am using ANYMP4 converter and dbPoweramp converters. The first generates raw AAC files; the latter generates m4a files. What surpised me most is the size difference on the output files (for the same quality: 256kbps).

Why is dbPoweramp bumpting up the file size (twice that of the outputs of the ANYMP4 converter)?

[Spoon]

The real size of a 256kbps file is easy to calculate, 256kbps = 32KB per second. If the track is 3 minutes long then:


60 * 3 * 32 = 5760KB or 5.7MB


if this other converter is half that size then it is not 256kbps...