mp4v2 changes iTunes's reading of bit rate

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Note bit rate of purchased iTunes song. In this case, 256 kbps.
2. Change or add release date to song.  (…or title, or possibly any other 
tag, as well, but I have not tested that.)
3. iTunes now reads the bit rate differently.  Sometimes it's as little as a 
change from 256 kbps to 258, sometimes it's from 256 to 189.

What is the expected output? What do you see instead?
I would expect the bit rate to stay the same.  Instead, it changes.

What version of the product are you using? On what operating system?
mp4v2-trunk-r369 on OSX 10.6.

Please provide any additional information below.
Call me picky, but this drives me cuh-ray-zee.

Original issue reported on code.google.com by chrisove...@gmail.com on 10 Sep 2009 at 6:56

[GoogleCodeExporter]

iTunes doesn't write the real bitrate, probably because people would just whine 
about it. Apple is using its aac 
encoder in the vbr constrained mode, so the bitrate is not always 256kbit/s.

Original comment by damiog on 15 Sep 2009 at 7:12

[GoogleCodeExporter]

Original comment by eddyg.o....@gmail.com on 22 Nov 2009 at 11:30

• Changed state: Invalid