[Ffmpeg-devel] ratecontrol advice
Fri Jul 29 08:17:20 CEST 2005
> 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
> 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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