[x264-devel] Re: QP related variables

[Laurent Aimar]

On Thu, Jul 15, 2004, Måns Rullgård wrote:
> I've been trying to figure out the meaning of the various QP related
> variables used during encoding.  From what I can see the global QP
> value is used for all MBs.  Is this the case, or have I overlooked
> something?
 Yes it's that case, a global qp per frame.

>  I also noticed a TODO comment in encoder/analyse.c, line
> 850.  What is this referring to?
  Implementing a RC that change QP per MB ;)
> 
> QP adjustments should be done by the rate control, so I need to know
> how to properly change the QP used for each MB.  Any hints there?
 Yes, the best is just to pass it to x264_macroblock_analyse and to replace
  h->mb.qp[h->mb.i_mb_xy] = x264_clip3( h->pps->i_pic_init_qp + h->sh.i_qp_delta + 0, 0, 51 );
by
  h->mb.qp[h->mb.i_mb_xy] = i_my_qp_for_this_mb;

It should work but I never tested if the bitstream is correct.

-- 
fenrir

-- 
This is the x264-devel mailing-list
If you are in trouble, please contact <postmaster at videolan.org>