[MPlayer-users] help wanted: using mencoder to make NTSC DVD from transport stream
113762 at vs.iki.fi
Sun Mar 6 14:31:29 CET 2005
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. But the resulting distortion in aspect ratio is only
justifiable if you already are quite close to the rounded size.
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