I thought that MP3GAIN did work since all MP3GAIN does is modify a global gain flag in the id3, but now that I have tested it I realize that it sure doesn't...I really wish I had known/noticed this before as I have converted basically my entire collection of mp3's to mp3PRO and been using MP3GAIN to change the volumes on a large number of them, and now the whole collection is f*cked

What I did to test it was opened up an MP3 in CoolEdit and saved it as an mp3PRO. I then took the original mp3 and applied a constant gain of -9.0 dB (so that if the SBR part wasn't being normalized with it, it would be more noticable) and saved this resulting lower-volume mp3 as another mp3PRO. I then opened up MP3GAIN and applied the same constant gain to the first mp3PRO file, so I now have 1.pro.mp3 with the gain applied after encoding and 2.pro.mp3 with the gain applied prior to encoding. Double checked that the volume analysis showed up with the same volumes, then did a sound test.

Results, 1.pro.mp3 (post-encoding gain) sounded like crap.. high frequencies untouched with low frequencies lowered.

SOOO, now I have a very important question -- is there any way to normalize mp3PRO's? That is, use a program that will normalize/take into consideration the SBR part as well?

AFAIK, mp3pro specs are not public so this isn't possible.

You could use wavgain on the wav's before encoding to mp3pro, to get replaygain functionality.

gonzopdx:

As far as I know SBR is encoded the following way: if you want for instance 64 kbps MP3PRO, it encodes approx. 60 kbps as an usual MP3 and 4 kbps are used for some math description of higher frequencies. This info is used by decoding with MP3PRO decoder (Spectral Band Replication = SBR); by decoding with a non-MP3PRO decoder it stays untouched...

Envelope data (energy value) is coded implicitly in the SBR bitstream, and without SBR specs for mp3Pro it is impossible to change the gain of the envelope data.

Hrm.. I guess my next question would be if there is any way to undo the gain info that MP3GAIN puts into the files..? Or any way to reduce the horribly high hissy treble resulting from my using MP3GAIN to normalize mp3PRO files?

Thanks for all your help guys..

Hi grivad... Why not try the solution presented by Voltron in the other "mp3gain" thread in this board?

http://www.hydrogenaudio.org/forums/index....f=15&t=6064&hl=