Original File Length (OFL) for mp3, mp3Pro, aac..., Gapless playback becomes possible. Options

[Ivan Dimkovic]

On AES 114th held in Amsterdam, Thomson Multimedia researchers presented a way to signal exact codec delay and file length in a backwards compatible fashion - in current mp3, mp3pro, aac, etc... coding algorithms. It is known as OFL - or Original File Length

Algorithm deals with non-exact file length and delays introduced by modern frequency-domain coding systems. Data for OFL is written in ancilliary data so it is completely backwards compatible - decoder without OFL will just ignore the OFL data.

OFL will allow gapless playback with OFL compatible decoders.

AES paper number is: 5830


PS: They are mentioning LAME in the paper

This post has been edited by Ivan Dimkovic: Mar 24 2003, 19:26

[mmortal03]

*it should be possible most of the time to update already existing files, but the question is how to know the delay of previously encoded files

Yeah, it all goes back to "which encoder was used", etc. This is more complex than say ReplayGain, in that this has to be much more specific. Even if we can't perfectly convert old files to OFL, it will still be worth it, regardless.