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Old 11th April 2008, 18:01   #1  |  Link
3NC0D3_Y0_A$$
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Ideas for New Concepts for Video Compression

Ok (this may be a bit noobish), So we know various video codec standards have different 'concepts' to encode video and reduce bitrate whilst maintaining quality to the human eye. I realize that a lot of video codec development is down to improving the efficiency or 'eloquance' of these video compression techniques and the languages they are written in.

The H.264 video codec standard has the following compression techniques:

CAVLC/CABAC, Loop/Deblocking Filter, Variable Block Sizes/Macroblock Partitions, Multiple Reference Frames, Weighted Prediction, Rate Distortion Optimisation (RDO).

What other video compression 'concepts' or techniques can you think of?

Its unlikely that anyone is generating a new video compression standard anytime soon, but it still would be interesting to see what ideas people can come up with.

Just for starters:
Perhaps encoding the edges of a still object into an equation for a shape (that outlines it) and also the inside of the shape if the colour is uniform. (this would be useful for distance objects in still shots)

Last edited by 3NC0D3_Y0_A$$; 11th April 2008 at 18:09.
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Old 11th April 2008, 18:55   #2  |  Link
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Its unlikely that anyone is generating a new video compression standard anytime soon, but it still would be interesting to see what ideas people can come up with.
New open standards are ratified quite often and some companies have their own closed "standards". As an example of an upcoming open (and royalty-free) standard, Dirac Pro is being standardized as SMPTE VC-2.

If you're interested in new techniques and innovations, I'd suggest checking out the abstracts of video compression research papers from the last five years or so.
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Old 11th April 2008, 19:29   #3  |  Link
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The only standard they could realistically go into is Snow, which has yet to be given a final specification.
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Old 11th April 2008, 20:22   #4  |  Link
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The only standard they could realistically go into is Snow, which has yet to be given a final specification.
Who could go? SMPTE? I seriously doubt Michael Niedermayer or other FFmpeg developers would ever consider going through such a standardization process for Snow. RFC maybe.

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Old 11th April 2008, 20:25   #5  |  Link
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Who could go? SMPTE? I seriously doubt Michael Niedermayer or other FFmpeg developers would ever consider going through such a standardization process for Snow.
Snow? can you explain what this means please?
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Old 11th April 2008, 20:30   #6  |  Link
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It's a wavelet codec in FFmpeg/libavcodec, written by Michael Niedermayer. See: http://en.wikipedia.org/wiki/Snow_(codec)
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Old 11th April 2008, 20:35   #7  |  Link
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It's a wavelet codec in FFmpeg/libavcodec, written by Michael Niedermayer. See: http://en.wikipedia.org/wiki/Snow_(codec)
cheers.
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Old 11th April 2008, 20:58   #8  |  Link
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ffmpeg's website has a notice that says a specification will be written up for Snow eventually, if there is enough interest. Until then, it's basically a free-for-all based on current code. I think it has CABAC and OBMC and inloop deblocking. Basically borrowing ideas from other codecs, and developing new techniques to make a usable codec to attack H.264 is I think Snow's final aim, but at the moment, speed is less than desirable.
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Last edited by Inventive Software; 11th April 2008 at 21:02.
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Old 12th April 2008, 02:19   #9  |  Link
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Originally Posted by 3NC0D3_Y0_A$$ View Post
CAVLC/CABAC, Loop/Deblocking Filter, Variable Block Sizes/Macroblock Partitions, Multiple Reference Frames, Weighted Prediction, Rate Distortion Optimisation (RDO).
Don't worry. Guys are already preparing H.265.


I'm not a professional of video compression but afaik central concept of lossy compression is transform (between temporal to (complex) frequency domains ) like DCT.


There is no proof that wavelet transform is better than (M)DCT.
Jpeg2000 (wavelet) is worse than intra H.264 based on DCT.


afaik it is planned that 2008 will be last year of changing reference source of H.264, new profiles etc... And there will be first papers about H.265 in 2009.
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Old 12th April 2008, 02:22   #10  |  Link
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There is no proof that wavelet transform is better than (M)DCT.
But unlike DCT, it can be used in combination with OBMC to avoid blocking altogether.
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Jpeg2000 (wavelet) is worse than intra H.264 based on DCT.
That's basically because its intra prediction is FIR instead of IIR.
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Old 12th April 2008, 08:24   #11  |  Link
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OBMC is not completely blocking free.

I think the improvements which can be gained by OBMC and wavelet coding in the end are only slight. IMO motion coding is the lowest hanging fruit for big improvements at the moment, motion motion compensation and per pixel lossy coding of the motion field.
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Old 12th April 2008, 08:33   #12  |  Link
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OBMC is not completely blocking free.

I think the improvements which can be gained by OBMC and wavelet coding in the end are only slight.
IIRC total residual can be decreased by about 25% using OBMC.
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Old 12th April 2008, 12:14   #13  |  Link
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Some of the high points that are being considered for inclusion in h265 are :
- 80+ prediction mode just for intra, which greatly increase intra efficiency
- intra frame motion vectors
- free macroblock partitionning for inter : instead of fixed 16x8, 8x16, 8x8... partitions, you can cut a block/macroblock in two by defining a cutting line however you want (not just vertical/horizontal, but any angle too)
- better syntax (for example, better motion vector prediction)
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Old 12th April 2008, 21:08   #14  |  Link
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That's basically because its intra prediction is FIR instead of IIR.
Which is in turn because I have yet to see anyone make IIR intra prediction compatible with wavelets, nor have I thought of a way myself.

@MfA:
Want to run Snow and point out a blocking artifact to me?

@Inventive Software:
Snow doesn't have inloop deblocking because it doesn't need it. OBMC+Wavelet doesn't produce blocking artifacts, so doesn't need to be deblocked.

Last edited by akupenguin; 12th April 2008 at 21:11.
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Old 12th April 2008, 21:21   #15  |  Link
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Which is in turn because I have yet to see anyone make IIR intra prediction compatible with wavelets, nor have I thought of a way myself.
Why is this? Isn't intra prediction entirely spatial, with wavelets merely being a way to encode the residual?
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Old 12th April 2008, 21:23   #16  |  Link
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If you're interested in new techniques and innovations, I'd suggest checking out the abstracts of video compression research papers from the last five years or so.
Goodness, did you ever read those papers on DCT, quantization, or compression domain transcoding?

That's a real quick way to feel like an idiot.
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Old 12th April 2008, 21:25   #17  |  Link
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H.264 spatial intra prediction predicts from the decoded pixels of the neighboring blocks. In any transform with overlapping basis vectors, the neighbors haven't been decoded yet. Plus you need a continuous prediction function if you want to retain the block-free nature.

Quote:
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If you're interested in new techniques and innovations, I'd suggest checking out the abstracts of video compression research papers from the last five years or so.
Don't try this at home, kids. The signal-to-noise ratio in video compression research is really low, so if you don't already have the intuition to cull the BS papers, reading isn't too useful.
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Old 12th April 2008, 21:35   #18  |  Link
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Originally Posted by 3NC0D3_Y0_A$$ View Post
Just for starters:
Perhaps encoding the edges of a still object into an equation for a shape (that outlines it) and also the inside of the shape if the colour is uniform. (this would be useful for distance objects in still shots)
This is quite similar to the way flash animation works. I've long thought that something like this could be very effective for anime content, but I have yet to see any sort of proof of concept idea for it. There are some tools out there that have become fairly decent at vectorizing a still image, but I have yet to see anything that can intelligently vectorize a video stream. Perhaps the mathematics behind it is just too complex.
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Old 12th April 2008, 21:43   #19  |  Link
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Why is this? Isn't intra prediction entirely spatial, with wavelets merely being a way to encode the residual?
I think the wavelet transform is done before anything else, then OBMC is done on top of that.
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Old 13th April 2008, 00:08   #20  |  Link
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Is there something like a 3 dimensional wavelet? If so, a scene could be encoded as a 3D wavelet, where the z-axis is the time axis.
No search algorithms, no motion vectors, no residual to encode. Memory usage would be huge however.
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