[Ffmpeg-devel] X264 ratecontrol wraper

Guillaume POIRIER poirierg
Tue Mar 14 08:04:54 CET 2006


On 3/13/06, M?ns Rullg?rd <mru at inprovide.com> wrote:
> Michael Niedermayer <michaelni at gmx.at> writes:
> > Hi
> >
> > is anyone interrested in writing a ratecontrol wraper for
> > ffmpeg-x264 similar to ffmpeg-xvid so all our codecs could use the
> > x264 rc code?
> The problem I see here is with the different quantizer range and
> qp/bitrate relationship.  Do you have a good mapping of the H.264 qp
> onto an equivalent mpeg2/4 quantizer?

Loren has written an empirical formula in MEncoder's man page:
he mapping is  approximately H264QP = 12 + 6*log2(MPEGQP).  For
example, MPEG at QP=2 is equivalent to H.264 at QP=18.

Reinventing the wheel certainly is annoying, but as long as all other
wheels are square...

Reimar D?ffinger

More information about the ffmpeg-devel mailing list