[Ffmpeg-devel] [PATCH] Snow multiple reference frames

Michael Niedermayer michaelni
Sun May 28 11:40:52 CEST 2006


On Fri, May 26, 2006 at 01:53:20AM -0700, Loren Merritt wrote:
> $subject.
> notes:
> * Reduces bitrate by anywhere from 0 to 15%. Very content dependent.
> * Doesn't modify mv prediction. It still takes a median of neighbors, 
> regardless of which ref they used.
> * Doesn't work very well at low bitrate or with 8x8 partitions. Maybe 
> I'm underestimating the cost of specifying refs, or maybe due to the 
> above prediction? (but an exact rangecoder cost didn't help either.)

patch looks great, apply!

some random ideas (yeah i should test them myself instead of being lazy and
posting them here ...)

instead of the h.264 MV prediction or the current trivial one we could 
try to simply scale the MVs so as to compensate for the reference 
difference (IIRC there was some MV scaling in early H.264 drafts but 
it was removed so maybe its not that good dunno)

we could try to store the refs only per 16x16 for the 8x8 blocks

maybe the ref could be used in the ac context of the mv or the other
way around

long term ref pictures, simply keep 1 frame prior to the last detected
scene change, so if 2 scenes switch between each other a few times
compression should be improved alot, this can also be done with
more then just the last scene change obviously


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is

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