At slice level global filtering strength is adjusted to the individual characteristics of the • – video sequence At block-edge level deblocking filter decision is based on inter or intra prediction of the • – block, motion differences and presence of coded residuals in the two participating blocks. At sample level it is important to distinguish between the blocking artifact and the true • – edges of the image. True edges should not be de blocked. Hence decision for deblocking at a sample level becomes important. 2.3.5 Entropy coding H.264 uses variable length coding to match a symbol to a code based on the context characteristics. All the syntax elements except for the residual data are encoded by the Exp- Golomb codes[1]. The residual data is encoded using CAVLC. The main and the high profiles of H.264 use CABAC. adaptive variable length coding (CAVLC): • After undergoing transform and quantization the probability that the level of coefficients is zero or +1 is very high [1]. CAVLC handles these values differently. It codes the number of zeroes and +1. For other values, their values are coded. Context-based adaptive binary arithmetic coding (CABAC): • This technique utilizes the arithmetic encoding to achieve good compression. The schematic for CABAC is shown in Figure 2.13. Figure 2.13 Schematic block diagram of CABAC [1] CABAC consists of three steps: Step 1: Binarization: A non-binary value is uniquely mapped to a binary sequence
• At slice level – global filtering strength is adjusted to the individual characteristics of the video sequence • At block-edge level – deblocking filter decision is based on inter or intra prediction of the block, motion differences and presence of coded residuals in the two participating blocks. • At sample level – it is important to distinguish between the blocking artifact and the true edges of the image. True edges should not be de blocked. Hence decision for deblocking at a sample level becomes important. 2.3.5 Entropy coding H.264 uses variable length coding to match a symbol to a code based on the context characteristics. All the syntax elements except for the residual data are encoded by the Exp- Golomb codes[1]. The residual data is encoded using CAVLC. The main and the high profiles of H.264 use CABAC. • adaptive variable length coding (CAVLC): After undergoing transform and quantization the probability that the level of coefficients is zero or +1 is very high [1]. CAVLC handles these values differently. It codes the number of zeroes and +1. For other values, their values are coded. • Context-based adaptive binary arithmetic coding (CABAC): This technique utilizes the arithmetic encoding to achieve good compression. The schematic for CABAC is shown in Figure 2.13. Figure 2.13 Schematic block diagram of CABAC [1] CABAC consists of three steps: Step 1: Binarization: A non-binary value is uniquely mapped to a binary sequence
Shreyanka_Subbarayappa_Final_Thesis_Report.docx