[MPlayer-users] Problem using vb_strategy=1

[D Richard Felker III]

On Fri, Dec 26, 2003 at 02:26:32AM +0100, Stefan Baehre wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> When using vb_strategy=1 in single-pass encoding, the number of
> b-frames used is always off by one from vmax_b_frames. So when
> doing
> 
> -lavcopts vcodec=mpeg4:psnr:vmax_b_frames=2:vb_strategy=0
> 
> I always get 2 b-frames, but when doing
> 
> -lavcopts vcodec=mpeg4:psnr:vmax_b_frames=2:vb_strategy=1
> 
> there is never more than 1 b-frame used, when doing
> 
> -lavcopts vcodec=mpeg4:psnr:vmax_b_frames=3:vb_strategy=1
> 
> there is never more than 2 b-frames used, and so on.
> 
> I'm not sure if vb_strategy=1 is supported in single-pass encoding at
> all. Manpage says "strategy to choose between I/P/B frames (pass 2)".
> Does this mean it should only be used in 2-pass encoding, or only
> that it should be used in the second pass when using 2-passes?
> 
> Quality often improves when using vb_strategy=1, even in single-pass
> encoding.

If this "bug" exists, it makes sense that quality always improves.
Using more than one B frame always reduces quality.

Rich