[MPlayer-users] PSNR Questions

[D Richard Felker III]

On Sat, Feb 15, 2003 at 05:32:04PM +0000, Ian wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
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> D Richard Felker III wrote:
> 
> >Huh?? This is nonsense. You can't compare PSNR relative to two
> >different reference 'signals'. When encoding, the source is considered
> >the signal, and the difference between the encoded picture and the
> >source is the noise, so the source has infinite PSNR automatically.
> 
> OK, this is the first time I've seen it stated, a formula would be nice 
> too, but in any case see below . . .
> 
> >Yes, theoretically. Computational issues might make it come out
> >different tho.
> 
> Regardless, since in my experience better quality material (ie. the 
> originals!) has a lower PSNR than the copies, I can't take it seriously. 
>  Obviously your experience is different.

How are you measuring the PSNR of the original?? Like I said, you have
to use the same reference to compare PSNR.

Rich