[MPlayer-dev-eng] [TOOLS] PSNR plot utility

[Jeff Clagg]

On Fri, Apr 29, 2005 at 12:31:01PM -0500, Zoltan Hidvegi wrote:
> I wrote a simple utility I've been using for a while to calculate and
> plot PSNR values.  The main reason I wrote this is to better
> understand the quality of multi-pass encoding, after I saw that in
> many cases mult-pass encoding increases global PSNR at the expense of
> allowing some really bad looking scenes.  In other words, the global
> PSNR may be high, even if 2% of the movie is almost unwatchable.  I
> did not like this so much, that recently I only use constant QP lavc
> encoding with well chosen lmin=lmax and v[bi]_q(factor|offset).

Not to derail this topic, but the default vqcomp is a bit low. 0.6 or
0.7 is usually better, and more closely matches constant QP. You should
definitely play with this before you cosider ditching 2pass altogether.