bond 22nd August 2005 05:34
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native mode is the way to store avc in mkv as defined in the mkv specs, anything else you need to know?
vfw mode is a special way for storing streams in mkv as some sort of "private stream" when going via the vfw codec interface (as used in virtualdub) meaning its nowhere defined how the stream is stored in the mkv
here a list about the downsides of vfw mode:
1) you will loose interoperability. if you dont use the native way its not ensured that your files will work with mkv tools meant to support avc following the specs.
placing avc in mkv the vfw way is like placing avc in some private not defined way in .mp4: its not ensured that the files will work anywhere
But I can play it with MPC and it works in VdubMod.
2) you will get decoding delays with any avc encoding mode not being support in vfw (that is b-frames, b-references or arbitrary frameorders without b-frames).
you will get a delay of 1 in case of b-frames plus 1 additional frame if b-pyramid is used (that is a delay of 80ms for a 25fps stream)
Since it is already avc in avi, will there be any difference ?
3) you will get an "encoding delay", so called delay frames into the stream. in the case of asp video they will break the compliancy of the video stream to the mpeg-4 standard, dunno if this is true for avc too.
that is an additional delay of 2 frames in the case of useage of 2 b-frames: 80ms (never tested how b-pyramid influences this, but surely not positively). i think the delay will be higher if you use more b-frames (eg 3 delay frames with 3 b-frames aso)
None of my business.
4) the framenumber of the stream will not be correct anymore. you will loose two frames in the case of using 2 b-frames (3 frames with 3 b-frames aso)
Again,since it is already avc in avi, will there be any difference ?
5) people will laugh at you if you use it ;)
???
