[MPlayer-dev-eng] [PATCH] mplayer.1: lavcopts lmin/lmax, vrc_buf_size

[Michael Niedermayer]

Hi

On Tuesday 28 October 2003 23:31, Tobias Diedrich wrote:
> Since I just found that the undocumented lmin/lmax parameters are
> needed for ratecontrol, this is my suggestion for the manpage:
>
> +.B lmin=<0.0\-99.9>
> +minimum average quantizer for ratecontrol, should be equal to or lower
> than +vqmin. (default: 2.0)
> +.RE
> +.TP
> +.B lmax=<0.0\-99.9>
> +maximum average quantizer for ratecontrol. (default: 31.0)
> +.RE
> +.TP
>
> I'm not sure if this is the correct description though, maybe Michael
> Niedermayer can comment on that.
no, its not correct, they limit the lagrange multiplier and their range is 
0.01 - 255.0 
and no i dont have a simple/understandable explanation
but the basic idea is rate control -> lambda-> quantizer (QP)
and 0.85QP^2 ~ lambda^2 or 0.92QP ~ lambda
so for simplicity we "scale" lambda to the QP range externally
lambda^2 is the lagrange multipler (for the SSE distortion function)

> I also propose to change the vrc_buf_size description as follows:
>
>  buffer size in kbit (pass\ 1/\:2).
> +For MPEG1/2 this also sets the vbv buffer size, use 327 for VCD,
> +917 for SVCD and 1835 for DVD.
>  Note: vratetol should not be too large during the second pass or there
> might be problems if vrc_(min|max)rate is used.
ok, but IMHO we should change ve_lavc.c to use 1024type kbit instead of 
1000type kbit for the buffer size

[...]
-- 
Michael
level[i]= get_vlc(); i+=get_vlc();		(violates patent EP0266049)
median(mv[y-1][x], mv[y][x-1], mv[y+1][x+1]);	(violates patent #5,905,535)
buf[i]= qp - buf[i-1];				(violates patent #?)
for more examples, see http://mplayerhq.hu/~michael/patent.html
stop it, see http://petition.eurolinux.org & http://petition.ffii.org/eubsa/en