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IMPLEMENTATION OF COMPLEXITY REDUCTION ALGORITHM FOR INTRA MODE SELECTION IN H.264/AVC. Santosh Kumar Muniyappa. Guided by - Dr. Rao. Contents. Need for video compression Motivation Video coding standards, video formats and quality Overview of H.264
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Santosh Kumar Muniyappa
- Dr. Rao
Removing redundancy in a video clip
Only a small percentage of any particular frame is new information
Highly complex process
Inter-operability between encoders and decoders from different manufacturers
Build a video platform which helps to interact with video codecs, audio codecs, transport protocols, security and rights management in well defined and consistent ways
CIF - common intermediate format
SIF - simple intermediate format
SDTV – standard definition television
PSNRdB = 10 log10 ((2n − 1)2 / MSE)
where, n = number of bits per pixel
I (intra) slice – contains reference only to itself.
P (predictive) slice – uses one or more recently decoded slices as a reference (or prediction) for picture construction.
B (bi-predictive) slice – works similar to P slices except that former and future I or P slices may be used as reference pictures
SI and SP or “switching” slices may be used for transitions between two different H.264 video streams.
N4 – number of modes of a 4x4 luma block
N16 – number of modes of a 16x16 luma block
Computing the best mode for one macro block:
N8x (16xN4 + N16) = 4 x (16 x 9 + 4)
Diff = |a – m| + |b – n| + |c – o| + |d – p|, for vertical direction
Diff = |a – d| + |e – h| + |i – l| + |m – p|, for horizontal direction
Diff = |c – i| + 2·|d – m| + |h – n|, for diagonal down left direction
Diff = |b – l| + 2·|a – p| + |e – o|, for diagonal down right direction
Diff = |a – n| + 2·|b – o| + |c – p|, for vertical right direction
Diff = |a – h| + 2·|e – l| + |i – p|, for horizontal down direction
Diff = |b – m| + 2·|c – n| + |d – o|, for vertical left direction
Diff = |e – d| + 2·|i – h| + |m – l|, for horizontal up direction
Step 1 - For a 4x4 luma block, obtain avg and S
Step 2a - If S is larger than a threshold, T1, carry out RDO procedure for at most four candidate modes: two modes with minimum and second minimum Diff, and at most two modes from adjacent blocks. In this case, DC mode of adjacent blocks is excluded from RDO procedure.
Step 2b - If S is smaller than a threshold, T1, carry out RDO procedure for at most four candidate modes: one mode with minimum Diff, at most two modes from adjacent blocks, and DC mode.
Note: T1 is set to 32
CIF - 30 frames
CIF and QCIF video sequences (a) bridge-close (b) bridge-far (c) coastguard (d) container (e) mobile
F. Pan et al, “Fast intra mode decision algorithm for H.264/AVC video coding”, in Proc.IEEE Int. Conf. Image Process., pp. 781–784, Singapore, Oct. 2004.
S. Kwon, A. Tamhankar, and K. Rao, “Overview of H. 264/MPEG-4 part 10, " Journal of Visual Communication and Image Representation, vol. 17, no. 2, pp.186-216, April 2006.
A. Luthra, G. Sullivan and T. Wiegand, “Introduction to the special issue on the H.264/AVC video coding standard”, IEEE Trans. on Circuits and Systems for Video Technology, vol. 13, issue 7, pp. 557-559, July 2003.