[FFmpeg-devel] parameter ranges bug / minrate q

[tripp]

Hi,


--- On Sun, 7/20/08, Michael Niedermayer <michaelni at gmx.at> wrote:

> > -* To force the frame rate of input file to 1 fps and the output file 
> > to 24 fps:
> > +* To force the frame rate of input file (valid for raw formats only) 
> >to 1 fps and the output file to 24 fps:
 
> This could be considered a bug, i think we even have a issue 
> about it on roundup ...

issue 312,
a fix to the doc accuracy to have it remain as a request.

> > @@ -388,8 +383,15 @@
> >  Set video bitrate tolerance (in bit/s).
> >  @item -maxrate @var{bitrate}
> >  Set max video bitrate (in bit/s).
> > +Requires -bufsize to be set.
> >  @item -minrate @var{bitrate}
> >  Set min video bitrate (in bit/s).
> > +Most useful in setting up a CBR encode:
> > + at example
> > +ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate
> > 4000k -bufsize 1835k out.m2v
> > + at end example
> 
> ok
> 
> 
> > +It is of little use elsewise
> 
> ok
> 
> 
> > +and when setting a -minrate that doesn't equal
> > -maxrate you'll get this warning:
> > +Warning min_rate > 0 but min_rate != max_rate isn't recommended!
> >  @item -bufsize @var{size}
> >  Set video buffer verifier buffer size (in bits).
> >  @item -vcodec @var{codec}
> 
> iam not sure about this, this doesnt seem too usefull ...

it links a console output error to the docs.
i'd call it reassuring,
indicating expected behaviour.

i'm not married to it.

> >  @item -qcomp @var{compression}
> > -video quantizer scale compression (VBR)
> > -
> > +video quantizer scale compression (VBR) (range 0.0 - 1.0,  default 0.5)
> 
> not strictly true

regarding default value?

> > +it's not recommended to set this value at its extremes.
> >  @item -lmin @var{lambda}
> >  minimum video lagrange factor (VBR)
> >  @item -lmax @var{lambda}
> 
> why?

lifted straight from mencoder docs,
where it also says qcomp 1 = CQ encoding
qcomp 0 = CBR
(assuming default rc_eq)

it's not recommended to set this value at its extremes
with the dafault rc_eq?

> [and yes you will have to split the seperate things unless
> diego or another is in very good mood and does it ...]

meaning i have to split it into like 4 patches?
minrate
bitstream filter add
issue 312 partial fix
defaults and ranges


i couldn't find patch submission guidelines.


ty
tripp