[MPlayer-users] Distortion between different versions of MPlayer/Mencoder

[D Richard Felker III]

On Sat, Oct 04, 2003 at 05:57:19PM -0700, Joseph N. Hall wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> > > Michael Niedermayer wrote:
> > > >i guess thats only happenig with files which have width or height %16 =! 
> > > >0, 
> > > Yes, that seems to fit.
> >
> > Never encode with width/height %16 != 0!! It will hurt quality a lot
> > even without buggy encoders!
> 
> This doesn't apply to lossless encoders like huffyuv, one assumes?

Of course. That's why you call it lossless... :)

> Does it apply to anything other than MPEG{1,2,4}-type encoders?

No, but basically everything non-lossless is MPEG{1,2,4}-type,
including vp3/theora. (Yes, you heard me right: it's essentially the
same thing and pretty much any patent applying to mpeg also applies to
theora. Of course all these patents are invalid because they're
obvious and the technology was invented well over 50 years ago, but
that's another matter...)

> And are there cases where block sizes of 8 are as good as 16?

For the most part, no. Chroma is subsampled, so an 8x8 chroma block
comprises 16x16 (for standard 4:2:0) of the full image dimensions.
Thus, while individual mpeg blocks are only 8x8, you need dimensions
that are multiples of 16 to keep from having incomplete chroma blocks.

Rich