[Ffmpeg-devel] ratecontrol advice
Thu Aug 11 02:22:41 CEST 2005
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
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.
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