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more on H.264's quantization parameter 

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@14489 b3059339-0415-0410-9bf9-f77b7e298cf2
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lorenm 2005-01-13 20:13:00 +00:00
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@ -7062,11 +7062,10 @@ This selects the quantizer to use for P-frames.
I- and B-frames are offset from this value by ip_factor and pb_factor, respectively.
20\-40 is a useful range (default: 26).
Lower values result in better fidelity, but higher bitrates.
Note that quantization in H.264 works differently from MPEG-1/2/4.
Note that quantization in H.264 works differently from MPEG-1/2/4:
H.264's quantization parameter (QP) is on a logarithmic scale.
As an example, the bitrate difference between QP=20 and QP=40
is about a factor of 10.
Useful quantizers in H.264 tend to be very large compared to MPEG-1/2/4.
The mapping is approximately H264QP = 12 + 6*log2(MPEGQP).
For example, MPEG at QP=2 is equivalent to H.264 at QP=18.
.
.TP
.B pass=<1\-3>