[XviD-devel] some question about xvid and mpeg4

James Hauxwell xvid-devel@xvid.org
Fri, 24 Jan 2003 13:16:11 -0000


Yes you can change the quantizer per macroblock.  Table B1 has the cbp
for the types of block.  Section 6.2.6 in the spec describes where it
fits in the macroblock() header.  I would hope that the encoder is
taking advantage of this, as it is the only way to do variable
quantization for rate control.  If the encoder is not then the quality
can be much improved over what it currently is.

Jim

-----Original Message-----
From: xvid-devel-admin@xvid.org [mailto:xvid-devel-admin@xvid.org] On
Behalf Of elcabesa@inwind.it
Sent: 24 January 2003 13:00
To: xvid-devel@xvid.org
Subject: [XviD-devel] some question about xvid and mpeg4

hi
i'm another time here to ask you some info aobut xvid and  mpeg4
standard

1) What is GME and GMC, i can only guess Global motion camera. for gmc
and 
Global motion estimation. if my guess is right how thyis motion is
searched?   
only by translation, zoom and  rotation of image , sometnigh more,
something 
less,or i'm totally out of the way??

2) qunatizer is a costant for each frame? i looked inside encoder.c and
seems 
to me that it's a value that chagne every frame. so each frame has ony
one 
quantizer.
is possible or Mpeg4 compliant change quantizer during a frame?


thank'you



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