[Ffmpeg-devel] ratecontrol advice

[Dario Andrade]

> 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