Like the title says.
I have video from my camera, AAC audio, H264 video.
I can edit the audio only with audio output filters but it does re-encoding.
Would it somehow be possible to use AACGAIN to have lossless gain?
In Avidemux - no. The feature is based on libmp4v2 which is to be removed from Avidemux and is not available in VC++ builds. In general, it feels IMHO utterly ugly to write "com.apple.iTunes" to a file. At the same time, the "volume" field in tkhd seems to be completely ignored :o
Why not just let the original aacgain utility process the output of Avidemux?