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Diffstat (limited to 'ext/tarkin/WHAT_THE_HECK_IS_THIS_CODE_DOING')
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diff --git a/ext/tarkin/WHAT_THE_HECK_IS_THIS_CODE_DOING b/ext/tarkin/WHAT_THE_HECK_IS_THIS_CODE_DOING new file mode 100644 index 00000000..46602605 --- /dev/null +++ b/ext/tarkin/WHAT_THE_HECK_IS_THIS_CODE_DOING @@ -0,0 +1,61 @@ + +This is deprecated. Take a look in the w3d/docs directory. + +The command line semantics are changed. You have to call the test program +now like this: + +./tarkin_enc ../clips/venuscubes-ppm/AnimSpace00%03d.ppm 5000 4 4 +./tarkin_dec + +------------------------------------------------------------------------------ + +Hi, + +this is a experimental 3d-integer-wavelet-video compression codec. Since the +integer wavelet transform is reversible and a reversible rgb-yuv conversion +is used (you can understand it as (1,2) integer wavelet transform, too), this +codec should be lossless if you transmit the whole bitstream. +The Y/U/V-bitstreams are embedded, thus you can simply get lossy compression +and shape the used bandwith by cutting bitstreams, when a user defined limit +is reached. + + +Here is how the current code works: + +First we grab a block of N_FRAMES frames (defined in main.c) of .ppm files. +Then each pixel becomes transformed into a YUV-alike colorspace. Take a look in +yuv.c to see how it is done. Each component is then transformed into frequency +space by applying the wavelet transform in x, y and frame direction. +The frame-direction transform is our high-order 'motion compensation'. +At boundaries we use (1,1)-Wavelets (== HAAR transform), inside the image +(2,2)-Wavelets. (4,4)-Wavelets should be easy to add. See wavelet.c for details. + +The resulting coefficients are scanned bitplane by bitplane and +runlength-encoded. Runlengths are Huffman-compressed and written into the +bitstreams. The bitplanes of higher-frequency scales are offset'ed to ensure a +fast transmission of high-energy-low-frequency coefficients. (coder.c) +The huffman coder is quite simple and uses a hardcoded table, this can be done +much better, but I wanted to get it working fast. + +Decompression works exactly like compression but in reversed direction. + +The test program writes for each frame the grabbed original image, the y/u/v +component (may look strange, since u/v can be negative and are not clamped to +the [0:255] range), the coefficients (look much more like usual wavelet +coefficients if you add 128 to each pixel), the coefficients after they are +runlength/huffman encoded and decoded, the y/u/v components when inverse wavelet +transform is done and the output image in .ppm format. + +You can call the test program like this: + + $ ./main 20000 5000 5000 ../clips/%i.ppm + +which means: images are grabbed from directory ../clips/0.ppm, ../clips/1.ppm, +etc. The Y component bitstream is limited to 20000 Bytes, the U and V bitstreams +to 5000 Bytes. If the last argument is omitted, frames are taken from current +directory. + +Good Luck, + +- Holger <hwaechtler@users.sourceforge.net> + |