How does MPEG achieve compression?
Here are some typical statistical conditions addressed by specific syntax and semantic tools: 1. Spatial correlation: transform coding with 8×8 DCT. 2. Human Visual Response—less acuity for higher spatial frequencies: lossy scalar quantization of the DCT coefficients. 3. Correlation across wide areas of the picture: prediction of the DC coefficient in the 8×8 DCT block. 4. Statistically more likely coded bitstream elements/tokens: variable length coding of macroblock_address_increment, macroblock_type, coded_block_pattern, motion vector prediction error magnitude, DC coefficient prediction error magnitude. 5. Quantized blocks with sparse quantized matrix of DCT coefficients: end_of_block token (variable length symbol). 6. Spatial masking: macroblock quantization scale factor. 7. Local coding adapted to overall picture perception (content dependent coding): macroblock quantization scale factor. 8. Adaptation to local picture characteristics: block based coding, macroblock_type, adapti
