Just noticed that the mp3 cmd encoder offered by all4mp3 had a new version 1.3, which now suport vbr mode. You can download it at the following url:

http://www.all4mp3.com/tools/sw_fhg_cl.html


Whats New in Version 1.3:
New features - Encoder

* OFL feature:
OFL (Original File Length) is a tool that puts information about the orignal file's length in the bitstream. A decoder that is aware of such OFL information can analyze it and then decode the bitstream having the same starting point and length as the original file (any codec delay or flushing at the end will be removed).
"-ofl" is the relevant switch.
* VBR encoding:
the encoder can now produce bitstreams encoded with variable bitrate. Therefore five modes are provided that can be invoked with the "-m"-switch.
"-m 1..5" (where "1" represents highest quality and "5" lowest average bitrate).
Note: When encoding in VBR mode, "-br 0" must be used. CBR encoding is applied by using "-m 0" and the desired bitrate, e.g. "-br 128000" for 128kbit/s
* VBRI header:
the encoder can prepend information about a VBR encoded bitstream by producing a so-called VBRI header (VBRI = VBR Index table).
"-vbri" is the relevant switch.

Intresting huh,

I should have seen this before...

Has anyone tested to see if the OFL information is compatible with gapless information stored by LAME in its encodes?

I would suppose not... they still stick to VBRI headers instead of the much more widely used Xing headers.

When I tested, not compatible... I didn't dig deeper on how it's implemented (for MP3), though. I think OFL was presented at AES in 2003 and, well, ignored entirely by the industry.

Can people use it 4 developing Adobe Audition MP3 Surround filter?

OFL is just encoder delay and padding values stored inside the VBRI header. (Of course, FhG will not switch to the "Xing" header).

New Fraunhofer encoder v. 1.4 is available on all4mp3.com (dated 2007-07-11), features "minor changes and bugfixes".

Updated binary files are available for all platforms (Win32/64, Linux32/64, Mac OS X).