I had found this blog entry explaining how to convert an HD .mkv file to .mp4 suitable for playback on PS3 without re-encoding.
There were manual steps involving hexedit, which seemed prone to error. Also some "Other possible strings", which seemed a little random to me.
I did some investigation and some calculation, and I may be way off mark, but I've only seen certain combinations of output so I need some help.
I bring you 264level, a tool for displaying and changing the level code, in one or more files, in one quick run.
This archive contains sourcecode which should work in Linux or OS X, or any unixlike system really. It also contains a Leopard compiled intel binary and an x86_64 linux binary.
This is a commandline tool, so stay away if the commandline scares you.
Run it without a -l flag first, no arguments at all, for usage.
Without -l, (i.e. 264level <filename>) it will just read the current level.
If it's not 4.1 or 5.1, please mail me at the address in the readme.
Also in the readme are compilation instructions... they're not difficult, you just need Xcode installed. The version that came on your install media is probably ok, or you can download the latest from apple.
If you get use out of it, please send me an email to let me know.
Faye Pearson
Zippysoft.