Postgain in MP4

[bond]

a nice feature aac currently lacks currently is postgain support in mp4 (besweet sets a postgain tag in the user data of mp4, but no decoder uses it currently :( )

apple uses a similar way of storing postgain info with its soundcheck feature in itunes, which adds a "itunnorm" field to the mp4 (also a tag in udta), looking similar to this:
iTunNORM = 0000100A 00000C57 00005204 00004A58 000043BE 000043BE 00007FDD 00007FDD 0000458A 00004151

the way itunes stores this info has already been reverse engineered in this project (http://www.hydrogenaudio.org/index.php?showtopic=19156&st=0&), which allows to apply the same info (using replaygain) to mp4 files via foobar

currently obviously only apples itunes and ipod use this info for applying postgain on mp4 files, but this might change if someone would write a standalone "aacgain" app, able to use the same technique for applying gain on aac files not created by itunes ;)

[pogo stick]

So do you mean that -G or -hybridgain in -ota(..) of besweet is not working right with aac?
Or these switches are doing something else and I am not geting your post right? :confused:

-G
apply relative normlization on the encoded file ("post-gain normalization")

-hybridgain
apply absolute pre-gain and relative post-gain normalization ("hybridgain")

[pogo stick]

Oh, I got it.
15. What gain setting should I use to encode AAC with BSN/Oagmachine?

Eventhough BeSweet/Bsn has implemented Hybrid gain, there are no Directshow filters capable of using the hybrid gain information at this time. So it is not recommended at the moment. Instead use normalization or pregain.
Note to myself:http://forum.doom9.org/images/smilies/readfaq.gif