[MPlayer-users] Re: best encoder ?

Martin Hoffmann ma.hoff at t-online.de
Mon Jul 22 23:40:02 CEST 2002

> >>>btw: When using XVID with interlacing turned on, you do not need to
> >>>deinterlace an the picture will look more sharp (no motion blurring) -
> >>>However if you do not intend to playback on tv set then deinterlacing is
> >>>the best method !
> OIC, but since I *do* intend to do playback on TV, what side effects are
> there, if any ?
Deinterlacing gives blurry picture on some motion scenes !
Judge yourself: Record ntv (scrolling text at bottom) 
(1) play it as original VDR file 
(2) encode it with lavc WITHOUT -vop pp -npp lb 
(3) encode it with deinterlacing -vop pp -npp lb
(4) Then try Deinterlacing by dropping one field -vop pp -npp li (if i 
remember right)
Now judge yourself !
I guess you'll find (1) and (2) looking best ! (3) is blurry and (4) is less 
resolution !
Now, why not using (2) with lavc / divx ?? Because the encoder does not treat 
interlaced fields (lines) correctly - he will just encode "dumb" - so he 
wastes a lot of bits on the interlaced lines thinking these are high-details 
- this way we waste too much bits !
On the other hand, xvid with interlacing turned on decides on a per Macroblock 
basis (if i remember right) if it's interlaced or not ! So he will encode the 
whole picture (as it's not, or less moving on ntv) non-interlaced (as lavc) 
and the bottom part as interlaced ! (Basically encoding every odd and even 
lines seperately ...)

Regarding Wasted bitrate you should try (2) on any fast moving scenes that are 
full screen interlaced (e.g. TV Shows with camera movement!)

Try it !

> > + Correct Aspect Ratio sacling in case of 16:9 material (current is not
> > exactly :-()
> Hopefully this will be a configurable option ? Since I crop my
> "cinemascoped" movies an aspect ratio would be no good idea ;)
Don't get me wrong, AVI alway has sqare pixels per definition - I'm not going 
to break this for 16:9 material (for 4:3 i do, but that's another story) - I 
had just some mistake when scaling 16:9 material !
Now it does scale to the correct Y values: 720x405  or 480x270 and so on !
Old versions did scale to 480x432 which in fact is NOT 16:9 assuming sqare 
pixels !

Does this break anything you use ?
If so, tell me how it should be ? Leave it 480x576 (original resolution) - or 
what ?

> > So, cropping is heard to do automatically, since i have no way to analyze
> > pictures :-( Rescaling could be added depending on wanted_size and length
> > of
> You do have a way to analyse the pictures using something like
> mencoder -cropdetect -i mymovie.mpg -frames 500 -o yugga.avi
> but this is far away from being perfect since f.e. a TV stations logo
> which appears in the black area lets "cropdetect" think, the movie
> starts at that vertical position... But cropping by hand is *very*
> effective resulting in a much smaller sized AVI :)
Is the size gain really that much by cropping the bars ? I always thought this 
would not be much gain ...


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