mpeg4 trouble

Expanding qtmux to support mpeg4 was going all well, everything was almost ready! Then the ES Descriptor appeared. For .mov files it was only used for AAC description atoms. For mpeg4 it has to be used for every format, and:

1. This ES Descriptor has a DecoderConfigDescriptor that has 'objecttype' and 'streamtype' integer fields that would identify the stream format and I can find no info on how to map the formats to those values (other than AAC).
2. The DecoderConfigDescriptor has some 'bitrate' and 'decoding buffer size' fields which aren't usually provided by GStreamer, so I'm just filling that up with zeros.

If there is someone out there that knows how to map formats to those fields or any idea on how GStreamer could provide bitrate (perhaps tag events?) I'd really appreciate some help. I've been stuck for almost a week.

Also I've started to test the mpeg4 files in a PS3, too bad it doesn't give meaningful error messages.