[Ffmpeg-devel] ratecontrol advice

[Dan Finkelstein]

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 I 
need, perhaps something like rc_initial_buffer_occupancy?

Thanks very much, I'm a bit puzzled how the encoder should be properly 
initialized,
Dan


At 11:17 PM 7/28/2005, Dario Andrade wrote:

> > My 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
> >
> > Other values were left at default values.  I'm not sure what you mean by
> > i_q_factor and strict VBV ratecontrol-- can you explain?
> >
> > With these settings I get I frames of around 8K bytes and P frames of
> > about
> > 50 -> 1000 bytes depending on the motion.   Also, I find that the bit_rate
> > varies a lot -- it might be quite a bit higher than 118000.
>
>
>You should also set rc_max_rate and rc_buffer_size for strict CBR operation.
>Quality will certainly degrade, but bitrate behaves much better with this.
>
>Regards,
>Dario Andrade
>
>_______________________________________________
>ffmpeg-devel mailing list
>ffmpeg-devel at mplayerhq.hu
>http://mplayerhq.hu/mailman/listinfo/ffmpeg-devel