[Ffmpeg-devel] ratecontrol advice

[Dario Andrade]

> 
> My other settings are set dynamically but tend to be like this:
>          gop_size =  60
>          bit_rate = 118000
>          time_base.num = 1
>          time_base.den = 30
>          bit_rate_tolerance = 118000/5
>          qmin = 3
>          qmax = 10
>          mb_lmin = FF_QP2LAMBDA * qmin
>          mb_lmax = FF_QP2LAMBDA * qmax
> 

Dan, In my opinion, bitrate is too low for a qvga 30fps video.
Underflow happens when in the theoretic buffering model "detects" that the
produced bitstream will take longer than it needs to correctly be consumed
by a hypothetical decoder. So I'd try reducing parameters or increasing
bitrate.

Cheers,
Dario Andrade


> Thanks very much !
> Dan
> 
> At 10:47 AM 8/11/2005, Dario Andrade wrote:
> > > I have tried your suggestion and added these initialization
> parameters:
> > >
> > >          c->rc_max_rate = c->bit_rate * 2;
> > >          c->rc_buffer_size = c->bit_rate * 2;
> > >
> > > When I run this, the error "rc buffer underflow" is displayed
> repeatedly
> > > in
> > > my debug monitor.  Can you comment on whether the values that I have
> set
> > > these parameters to is reasonable?  Also, is there another parameter
> that
> >
> >What is the frame size, fps and codec you're using?
> >
> >Regards,
> >Dario Andrade
> >
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> 
>