[MEncoder-users] filesize become very big after convertion
phil at slug.org
Tue Aug 22 19:52:26 CEST 2006
Nicolas George wrote:
> Le quartidi 4 fructidor, an CCXIV, Phil Ehrens a écrit :
> > I haven't seem much *scaling* to that resolution, but I think that
> > *cropping* to 704x384 is common (to remove black borders from 16:9
> > in 4:3 letterbox) and doesn't degrade the image.
> Yes, if it is cropping, it is certainly a good thing, although I doubt that
> any codec will waste a lot of bits in the constant black areas.
It's not the black, it's the noisy transition between the black and the
image that is common with less-than-stellar-quality dvd's.
> But you must keep in mind that although DVD have a 1.25:1 or 1.5:1 aspect
> pixelwise, they carry tags that indicates that they should be viewed at 4:3
> or 16:9. And good DVD will not needlessly use 4:3 and encode black borders.
> Therefore, when you see 704×384, it is often the result of a 704×451
> cropping AND then a scaling. And this down-scaling is not always a good idea
> when the bitrate is enough.
Alas, there are far more dvd's that needlessly use 4:3 and encode
black borders than dvd's that do the right thing. Most dvd's are
not good. Most content was originally released on media other than
dvd and the transfers often leave a great deal to be desired.
Many people use the scale filter when all they really want is
cropping because there are many example scripts that show both used
together without explanation.
More information about the MEncoder-users