[FFmpeg-devel] CBP question

Germán Milano g.milano87 at gmail.com
Tue Nov 1 13:11:19 CET 2011

Hi everyone,

I'm trying to print out the DCT coeffs AFTER dequantization. In order to do
that, i had to take a look at the decode_cabac_residual_internal function
(in h264_cabac.c). Now, i know that the cbp param represents whether a luma
block (and corresponding colour diferences blocks) has any DCT coeffs
distinct from zero. If i understand correctly, that is taken into account
in that function, in the following line:


I started with FFmpeg a couple of months ago, so i'm trying to understand
the terminology in order to fully understand the functions. So, i have the
following questions:

   - h -> mb_x and h -> mb_y are the coordinates of the mb in the frame?,
   is h -> mb_xy the dimension?
   - The DCTELEMENT passed to the function decode_cabac_residual_internal
   function is the one that gets 'filled up' with the DCT coeffs after
   dequant, isn't it?, i.e., h -> mb contains the DCT coeffs after dequant?

I hope i'm not bothering anyone with my questions (sorry in advance if i



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