what kind of mpeg file am i looking at (001ba,001bb,001be)?

I need to extract various information such as bitrate, width & height,
from mpeg video files.  I have done research and found that I should
be looking for a start code of

00 00 01 B3 

but in the file I have, I see the start codes of

00 00 01 BA
00 00 01 BB
00 00 01 BE

the file is supposed to be an MPEG2 video file, which I thought was
supposed to have the start code of 00 00 01 B3.  am i talking about
two different types of files here?

where can i find documentation on how to extract things such as
bitrate and width & height from the above mpeg file (the one with the
BA,BB,BE start codes)?

thanks!  

        mike