Yamb (free) and VLC Media Player (free) both give detailed stream info on these type files and are excellent MPEG4 toolbox items (along with GSpot that cholla mentioned, AVICodec, MediaInfo and many others). Here is a capture of Yamb's info for the audio track made using the iPodh264 5.5G profile (AAC audio): this is the older version of Yamb, the newer UI looks a little different.