better descriptions for remaining, poorly documented masking options.

vi_qfactor description
Kudow to Loren Merrit


git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@13483 b3059339-0415-0410-9bf9-f77b7e298cf2

DOCS/man/en/mplayer.1

@@ -5523,7 +5523,7 @@ quantizer factor between B and non B frames (pass\ 1/\:2) (default: 1.25)
 .
 .TP
 .B vi_qfactor=<-31.0\-31.0>
-(pass\ 1/\:2) (default: 0.8)
+quantizer factor between I and non I frames (pass\ 1/\:2) (default: 0.8)
 .
 .TP
 .B vb_qoffset=<-31.0\-31.0>
@@ -5854,12 +5854,26 @@ sane range
 .TP
 .B tcplx_mask=<0.0\-1.0>
 temporal complexity masking (default: 0.0 (disabled))
+Imagine a scene with a bird flying across the whole scene, tcplx_mask
+will decrease the quantizers of the bird's macroblocks (thus decreasing their
+quality) as the human eye usually does not have time to see all the bird's
+details.
+Be warned that if the masked object stops (e.g.\& the bird lands) it is
+likely to look horrible for a a short period of time (until the encoder
+figures out that the object is not moving and needs refined blocks).
+The saved bits will be spent on other parts of the video, which may increase
+subjective quality, provided that tcplx_mask is carefully chosen.
 .
 .TP
 .B scplx_mask=<0.0\-1.0>
 Spatial complexity masking.
 Larger values help against blockiness, if no deblocking filter is used for
-decoding.
+decoding, which is maybe not a good idea.
+.br
+Imagine a scene with grass (which usually has a great spatial complexity),
+a blue sky and a house, scplx_mask will raise the quantizers of the grass'
+macroblocks (thus decreasing its quality), in order to spend more bits on
+the sky and the house.
 .br
 .I HINT:
 Crop any black borders completely as they will reduce the quality
@@ -5870,10 +5884,20 @@ disabled (default)
 .IPs 0.0\-0.5
 sane range
 .RE
+.sp 1
+.I NOTE:
+This setting does not have the same effect as using a custom matrix that
+whould compress high frequencies harder, as scplx_mask will reduce the
+quality of P-blocks even if only DC is changing, which will probably not
+look as good.
 .
 .TP
-.B p_mask=<0.0\-1.0>
-inter MB masking (default: 0.0 (disabled))
+.B p_mask=<0.0\-1.0> (also see vi_qfactor)
+Reduces the quality of inter blocks, which is equivalent to increasing
+the quality of intra blocks, since the same average bitrate will be
+distributed by the rate controller to the whole video sequence
+(default: 0.0 (disabled)).
+p_mask=1.0 doubles the bits allocated to each intra block.
 .
 .TP
 .B naq\ \ \ \