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Written by Daniel P
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Tuesday, 25 July 2006 |
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For end-users, a video file is something you can watch in your favorite player. For
a programmer, there is not much in common between a Mpeg-2 coming from a DVD and an
uncompressed AVI, for example. MS is not helping here. There are only two video files
coming with DirectShow in the platform SDK and skiing.avi is not an AVI file. It's
an Mpeg-1 file. You can test it by opening it in a binary editor, and all AVI files
start with "RIFFxxxxAVI "; this sequence in nowhere to be found at beginning of skiing.avi.
Anyway, I wanted to mention that the Windows Media Video 9 codec is an implementation
of what has become the standard SMPTE VC-1. If you search the net, you can find the
reference implementation for the standard, I suppose that it is a portable and slower
version of the code for the WMV 9 codec. This code, together with Geraint Davies'
WMV parser, can give you a lot of informations about the processing of ASF files.
I also wanted to mention that this codec is available as a Vfw codec from MS. So you
can create very good AVI video files for the Windows platform without paying royalties
to anyone. Not a bad deal...
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