MASTER THESIS Video Watermarking - Computer Graphics Group ...

3.3 Decoding
The decoding process is reversal process to encoding resulting in visual
video data, as depicted in Figure 7.
Incoming slices are decoded, using the same entropy coding as in the
encoding process, up to intra prediction modes or motion vectors and quantized
transform coefficients.
Macroblock by macroblock, block by block, the quantized transform
coefficients are scaled to the former range, i.e. multiplied by dequantization
factors, and transformed by inverse frequency transform. Hereby, the prediction
residual is obtained.
Figure 7: Decoding process scheme
The prediction process is invoked using the intra prediction mode in case of
intra prediction, or the motion vector in case of inter prediction. Predicted
samples are added to the residual.
Such decoded blocks and macroblocks are joined together to form the visible
picture that is stored in the buffer of reference pictures for the inter prediction
process in next pictures.
In both encoding and decoding processes, deblocking filter process is invoked
over decoded pictures to increase final visual quality. The process eliminates
blocking artefacts on block borders, as may be seen in video sequences
compressed according to many of previous video coding standards at lower
bit-rates.
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