How can I convert the AAC audio in an MP4 from CBR to VBR?

Question

I'm trying to get MP4 video files I have created in Corel VideoStudio to play on an XBox 360 via streaming from a NAS device.

In my question on gaming.stackexchange.com, it's come up, that perhaps the constant bit rate audio is the cause of incompatibility.

I am able to convert the MP4 file to an MP4 file using YouTube Downloader that will play on the XBox. The YouTube Downloader generated file has VBR audio.

With the conversion process I think that the video quality is getting degraded. How can I convert just the audio from CBR to VBR?

Answer 1

You can use Avidemux or Yamb to separate audio and video tracks, then convert the CBR to VBR audio and use avidemux to join them together.

I had a slightly different issue (see my question here) but in playing around with the tools recommended, I found this functionality.