Inverse Quantization

Each of the decoded DCT coefficients in block should be inverse quantized through multiplication by the corresponding value from the weighting matrix and by the quantizer scale factor, which are read from the bit stream. Before this operation is performed, the DCT coefficients should be rearranged from zigzag scanning sequence to linear sequence.

For intra-frames all the DCT coefficients in block are processed, except the DC coefficient that should be processed separately in decoder, as described in MPEG standard. The functions for non-intra frames process all the DCT coefficients in block.

• QuantInvIntra_MPEG2
  Performs inverse quantization for intra frames according to MPEG-2 standard.
• QuantInv_MPEG2
  Performs inverse quantization for non-intra frames according to MPEG-2 standard.

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