[Mp4-tech] SA-DCT Approach

Andrew Kinane kinanea eeng.dcu.ie
Wed Nov 12 14:36:51 EST 2003


Hello,
I was wondering if it is a normative part of the MPEG-4 standard to take the
SA-DCT of the columns of an 8x8 block followed by taking the SA-DCT of the
resulting rows (coupled with taking and SA-IDCT of rows followed by the
SA-IDCT of the resulting columns) i.e an encoding decoding sequence of
COLUMN -> ROW -> ROW -> COLUMN
What I am asking really is: is it permitted to do the sequence
ROW -> COLUMN -> COLUMN -> ROW
I am asking this since for the shape adaptive transforms
COLUMN -> ROW -> COLUMN -> ROW and
ROW -> COLUMN -> ROW -> COLUMN
may give erroneous results depending on the alpha mask for a boundary 8x8
block so it is important that the SA-DCT and SA-IDCT be compatible in this
sense.
Thanks,
Andy


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