92 Why is the DC value always divided by 8 ? (MPEG-2)
Description
This article is from the MPEG FAQ, by Frank Gadegast phade@cs.tu-berlin.de with numerous contributions by others.
92 Why is the DC value always divided by 8 ? (MPEG-2)
Clarification point: The DC value of Intra coded blocks is quantized by
a constant stepsize of 8 only in MPEG-1, rendering the 11-bit dynamic
range of the IDCT DC coefficient to 8-bits of accuracy. MPEG-2 allows
for DC precision of 8, 9, 10, or 11 bits. The quantization stepsize is
fixed for the duration of the picture, set by the intra_dc_precision
flag in the picture_extension_header().
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