Shrink/alter timebase in AAC audio without re-encoding?

[Chug a Bug]

As title suggests, is it possible to "shrink" the timebase of an AAC audio w/o reencoding?

The reason is this: I have 3 separate videos derived from youtube that I want to stitch together they're all part of the same sequence and I want to join them into a single video file.

Now I can do this without any problems using AVIdemux, the trouble comes with the 2nd of the 3 videos the problem is the different framerate of the videos, vid 1 is 30fps, vid 2 is 29.97fps and vid 3 is 30fps again (no, I don't know why youtube created them thus, they just are. I've tried downloading different ways etc and the result is always the same.)

Now if I can shrink the timebase of the 2nd vid so that when I speed up the video framerate to match the other 2 vids i.e. to 30fps the audio will stay in sync with with video, but is there any way of doing that without re-encoding the audio?

It's rather poor quality sound and I don't want any more lossy re-encoding to make it worse. The thing is I want to keep the audio as AAC so I can mux it in an MP4 container.

Does anyone know of any tool that can do this? Thanks.

[jman98]

You can't do it without re-encoding, but properly done you probably won't notice a difference. Or at least I can tell you that properly done that MOST people won't be able to tell a difference.

Various audio editors can do this. The old commercial CoolEdit program can do this. Audacity is free. I am not sure if it can work with AAC audio but if it can then I think it can also do this.