[FFmpeg-devel] P/B - frames coeffs

Germán Milano g.milano87 at gmail.com
Sat Nov 19 15:09:38 CET 2011

Hi everyone!..

I am decoding a video stream in h264 using ffmpeg, and printing out the DCT
coeff after dequantification. To corroborate this I am using VisualMpegPRO
and checking out wether coefficients per macroblock have the same value
(between ffmpeg print outs and VisualMpegPRO) and going over the order in
which they are stored.

I could check all this for I macroblocks: all coeff are stored in h->mb and
I noticed that DC coefficients are not dequantized. Why does this happen???

However, I couldn't conclude the same thing for P and B macroblocks (print
outs don't match with VisualMpegPRO results). Are DCT coeff stored in the
same structures for P and B macroblocks as in for I??? If this is so, how
are they stored?

Thanks in advance!

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