[theora-dev] Theora Directshow Filter

Milan Cutka cutka at szm.sk
Fri Apr 9 04:00:49 PDT 2004

i> Excellent... i have a few weeks off after i go away for the weekend. I am
i> hoping to tidy up all my source so it can be released and then people can
i> better debug and implement integrated solutions. There's still a lot of
i> absolute pathing and other things like that in them, which needs to be fixed
i> up before anyone can easily build them on another machine.

i> Also... i'm curious... I assume you mean to channel theora streams to
i> ffdshow... not the other video codecs ffdshow supports ? Otherwise i'm
i> curious as to how the demux identified divx or other codecs ?

For now when getting video from your filter I'm just assuming it would be
theora encoded. If ogg container will support more video formats in
future, it shouldn't be too hard to support them too - at least for
ffdshow as video decoder filter.

i> When i get back... i'd be interested to check out some files (and BOS page

I'm sorry, but I don't know what BOS means.

i> formats) for the other codecs ffdshow supports, so i can put in proper
i> stream recognisers for them. If you could point me to some specs on the BOS
i> page formats you use for the other codecs that would be great.

If you'd like to demux other stream formats, try mp4 (quicktime) . AFAIK there is
no opensourced mp4 demuxer filter.

i> struct sTheoraFormatBlock {
i>  unsigned long theoraVersion;
i>  unsigned long width;
i>  unsigned long height;
i>  unsigned long frameWidth;
i>  unsigned long frameHeight;
i>  unsigned long frameRateNumerator;
i>  unsigned long frameRateDenominator;
i>  unsigned long aspectNumerator;
i>  unsigned long aspectDenominator;
i>  unsigned long maxKeyframeInterval;
i>  unsigned long targetBitrate;
i>  unsigned char targetQuality;
i>  unsigned char xOffset;
i>  unsigned char yOffset;
i>  unsigned char colourSpace;
i> };

Thanks. I "reverse engineered" width, height and frame rate. This was
enough for me now, maybe aspect ratio would be interesting too when
anamorphic theora clips will be available.


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