[MPlayer-users] help wanted: using mencoder to make NTSC DVD from transport stream

[D Richard Felker III]

On Sun, Mar 06, 2005 at 03:31:29PM +0200, Ville Saari wrote:
> On Sun, Mar 06, 2005 at 09:32:01AM +0100, Nico Sabbi wrote:
> 
> > >> mencoder $i -vf scale=720:-2,expand=720:480 -o dvd.mpg \
> ...
> > -vf scale=x:-2 scales y so as to keep proportions, so whether the 
> > original A/R is 4/3, 16/9 or 2.35
> > you will have a properly scaled picture in every case.
> > The only downside is that  -2 doesn't round to the closest x16 value, so 
> > you had better do it yourself.
> 
> The scaled size doesn't need to be divisible by 16 because you are
> expanding it to x16 size anyway. The final size out of the filter
> chain is the one that matters.
> 
> However the x16 vertical size has the advantage of aligning the
> edges of the black bars with the luma blocks improving the compression
> efficiency. x32 would be even better because then the also the chroma
> would align.

No, x16 already aligns the chroma. No need for 32, ever.

Rich