[Mp4-tech] Why in AVC standard the inverse Hadamar transform for DC chroma and DC luma precedes the inverse quantization process

[Shevach Riabtsev]

Dear experts 
Unless I am mistaken in AVC standard the inverse Hadamar transform for
DC chroma and DC luma precedes the inverse quantization process. This is
in contrast to the decoding of non-DC blocks. 
Indeed for non-DC block, the residuals shall be inverse quantized and
then inverse transformed, while for DC block the residuals shall be
inverse Hadamar-transformed and then inverse quantized (the obtained
results are then combined with AC inverse quantized coefficients to form
4x4 blocks and finally each 4x4 block is again inverse transformed).
Why AVC designers didn't accept the following chain of decoding
operationsfor DC blocks: first of all inverse quantize and then inverse
trensforms? What reasoning behind? 
Regards,  Shevach 
Broadcom
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