[MEncoder-users] avi sync questions

[Erik Slagter]

RC wrote:

>> Every time you change the resolution, the quality gets worse, scaling
>> is  a lossy process (if not scaled by exactly 2,4,1/2,1/4 etc.).

> That's not inherently true.  Simpler scalers, which do not interpolate,
> should be able to upscale and then after downscaling offer very close to
> original video.  sincR supposedly comes closest.

Still if you don't need it, I really wouldn't use it. It's comparable to 
an A/D and then D/A conversion cycle.

In case of a movie that was shot with a sensor of a certain resolution, 
you'd really want to have that dot-for-dot on your digital screen if 
possible. On a CRT it would matter less.

> It's a rare, exceptional DVD that doesn't have noisy edges transitioning
> to a few pixels of black around the fringes, which is almost as bad
> as non-16 dimentions (less likely to triger codec bugs--border_mask
> may help). 

In theory, yes. In practice I've actually seen more or less significant 
changes in file size (yes, with same quality of course). This may be a 
matter of taste.

> That is the recomended method of course, which is why cropdetect by
> default rounds down to multiples of 16.  It can be problematic in a few
> situations, however, where subtitles or the like are right at the edge
> of the screen.  Changing the offset (cropping more pixels at the top
> than the bottom) usually works, but not always.

Letterboxed material with wronly placed subtiles are the biggest pain of 
all :-( (even on DVD's this common practice..)