[Mp4-tech] [video][audio] asf muxing problems

[Ivan Dokmanic]

Hello,
I'm trying to write an ASF muxer, and have some questions.
1) When muxing VC-1 advanced profile video, what should I put in format 
extradata in stream properties (below BITMAPINFOHEADER structure). It 
seems that (in sample videos) VC-1 sequence header followed by entry 
point header should go there, but there are also some additional bytes 
(namely, the first one in VC-1 AP videos I checked out). Are there any 
special
notes that I should take into account? It seems that all files have 
packets with some padding, even though I don't find that necessary when 
reading asf specs.
2) I muxed MPEG audio and VLC media player plays it without problems. 
WMP doesn't want to play it. It doesn't play in graphedit either 
although I tried various (proper) combinations of filters. Why would 
that happen?
3) What should I put in extradata (type specific data) for formats like 
AAC, AC3 (is there some info on the web - I can't find much useful)?
Thanks plenty,
Ivan Dokmanic.