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MPEG2 FGS Implementation

MPEG2 FGS Implementation. ECE 738 Advanced Digital Image Processing Author: Deshan Yang 05/01/2003. Introduction of FGS. FGS = fine granularity scalability For MPEG2 / MPEG4 and others

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MPEG2 FGS Implementation

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  1. MPEG2 FGS Implementation ECE 738 Advanced Digital Image Processing Author: Deshan Yang 05/01/2003

  2. Introduction of FGS • FGS = fine granularity scalability • For MPEG2 / MPEG4 and others • Comparing to SNR, temporal, spatial scalability, FGS enhances video quality continuous instead of stepwise. • Using bitplane coding for enhancement layer, base layer is still using regular MPEGx coding • Enhancement layer bitstream can be truncated. The quality of video stream is proportional to the amount of enhancement bitstream data used.

  3. Project outline • Implement MPEG2 FGS enhancement into the current MPEG2 codec project from MPEG MSSG (MPEG Software Simulation Group). • Implementation includes: • Updating the current MPEG2 codec source code to support FGS • Implementing bitplane VL Codec and bit streaming • Implementing a new FGS enabled MPEG2 player • Challenges • Understanding and using the MSSG MPEG2 codec source code (much more difficult than it seems to be) • Bitplane coding / decoding • MPEG2 player on Windows platform • Media data to play with

  4. Project outline (cont.)

  5. Source code • MPEG2 codec source code is from:MPEG Software Simulation Group (MSSG) athttp://www.mpeg.org/MPEG/MSSG/ • MPEG2 player source code: searching google.com for mpg2w11b.zip. • My MPEG2 FGS player is combined from the the MPEG2 player with my MPEG2 FGS decoder MPEG2 player source.

  6. MPEG2 Encoder • More configurable options to control FGS encoding. • Integrating FGS enhancement layer bitplane encoder into the original MPEG2 encoder • Encoding base layer in very low bit rate • Calculate the DCT coefficients residues before and after the quantization step. • Encoding the DCT coefficients residues with the bitplane VLC • Encoded bitplane VLC output data are stored (as binary files) as the enhancement layer bitstream • Supporting I-frame and P-frame, not B-frame

  7. MPEG2 FGS Encoder Architecture

  8. MPEG2 Decoder • More configurable options to control FGS decoding • Integrating the FGS bitplane VLD into the original MPEG2 decoder • Accessing the enhancement layer bit stream (from binary files on disk) • Decoding DCT residues from the enhancement bit stream • Control the degree of enhancement • Generating the enhanced DCT coefficients • Decoding the enhanced DCT coefficients to get better video over base layer • Supporting I-frame and P-frame, not B-frame

  9. MPEG2 FGS Decoder Architecture

  10. MPEG2 Player • Combination of original MPEG2 player with the new MPEG2 FGS decoder • New features • Supporting FGS • Replay • Stop • Stretching to window • Supporting wide screen format • FGS scale change on the fly • Turning FGS on/off • Player window resizing • Supporting new command line options

  11. DCT Coefficients • Before quantization88,-14,0,0,-3,0,0,0,-40,-2,-2,0,0,0,0,0,-7,8,3,0,0,0,0,0,-5,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,0,0,2 • After base layer quantization88,0,0,0,0,0,0,0,-32,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,-0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 • Difference0,-14,0,0,-3,0,0,0,-8,-2,-2,0,0,0,0,0,-7,8,3,0,0,0,0,0,-5,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,0,0,1 • Sign bitsx,1,x,x,1,x,x,x,1,1,1,x,x,x,x,x,1,0,0,x,x,x,x,x,1,x,x,x,x,x,x,x,x,0,x,x,x,x,x,x,x,0,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,0,x,x,x,x,0 • Compressed sign bits1,1,1,1,1,1,0,0,1,0,0,0,0

  12. Bitplane coding • DCT coefficient differences:0, -14, 0, 0, -3, 0, 0, 0, -8, -2, -2, 0, 0, 0, 0, 0, -7, 8, 3, 0, 0, 0, 0, 0, -5, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0 • Bit planes: 0: 0000000000000000000000000000000000000000000000000000000000000000 1: 0000000000000000000000000000000000000000000000000000000000000000 2: 0000000000000000000000000000000000000000000000000000000000000000 3: 0000000000000000000000000000000000000000000000000000000000000000 4: 0100000010000000010000000000000000000000000000000000000000000000 5: 0100000000000000100000001000000000000000000000000000000000100000 6: 0100100001100000101000000000000001000000010000000000000000000000 7: 0000100000000000101000001000000001000000010000000000000000000000 8: 0200200022200000211000002000000001000000010000000000000000100000 (sign bits) • Compressed sign bits: 1,1,1,1,1,1,0,0,1,0,0,0,0 • Bitplane VLC encoding Planes 0,1,2,3 are all zero Plane 4: (1, 0, 0), (6, 0, 0), (8, 1, 0) Plane 5: (1, 0, 0), (14, 0, 0), (7, 0, 0), (33, 1, 0) Plane 6: (1, 0, 0), (2, 0, 0), (4, 0, 0), (0, 0, 0), (5, 0, 0), (1, 0, 0), (14, 0, 0), (7, 1, 0) Plane 7: (4, 0, 0), (11, 0, 0), (1, 0, 0), (5, 0, 0), (8, 0, 0), (7, 1, 1)

  13. Bitplane coding (cont.) Code format: BPnnnnnn B: End of block flag, P: End of plane flag, nnnnnn: number of 0 before 1 3F=00111111=“All zero plane”, BF=0x10111111=“All planes are zero)

  14. Bitplane VL Codec • VLC • Splitting DCT coefficients to bitplanes • Converting each bitplane to VL codes • Converting VL codes to binary codes (Huffman codes) • Storing binary codes as enhancement layer bitstream (binary file) • VLD • Loading binary codes from enhancement layer bitstream (binary file) • Converting binary codes (Huffman codes) to VL codes • Converting VL codes to bitplanes • Merging bitplanes to DCT coefficients

  15. Enhancement Layer Bitstream

  16. No FGS 15% FGS 65% FGS 30% FGS 30% FGS

  17. Demo • Run fgs.bat

  18. Issues • Enhancement layer bitstream size is much bigger than the base layer bitstream size. • Motion prediction can not be applied to enhancement layer • Current implementation only supports I-frame and P-frame, not B-frame yet • Current implementation does not support Huffman VLC coding in the bitplane VLC. I don’t have a good Huffman VLC table, and Huffman VLC will only help to reduce the enhancement bitstream size ¼ anyway.

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