[x264-devel] unsubscribe

[arezki redouane]

Please unsubscibe me now

----- Message d'origine ----
De : Gregor Riepl <seto-kun at freesurf.ch>
À : Mailing list for x264 developers <x264-devel at videolan.org>
Envoyé le : Mercredi, 28 Novembre 2007, 18h38mn 16s
Objet : Re: [x264-devel] I444 support

> Yes, x264 offers very good quality/compression ratio, in particular
 at
> high compression rates. I would not be so sure this is still true
 with
> VERY LOW compression like with qp-values of around 0. I don't know,  
> but
> you might very well get a data expansion (even more so with 4:4:4).
> Also, at very low compression rates (high data rates) the gain from
> temporal prediction (motion compensation) can be very small. So,
> consider to use a pure INTRA compression scheme like JPEG2000. For
> instance the Kakadu JPEG200 encoder already includes 4:4:4 RGB
> compression.

thanks for the hint. i'll have a look.

> Finally, of cause I don't know what exactly you try to archive. But,
  
> if
> the material is old and/or analog or if your film scanner (for analog
> sources) only has a limited quality, it will definitely not be worth
> archiving at very high data rates. In that case you would just waist
> expensive storage room to archive a lot of noise...

ok, let me be a little bit more specific. i'm dealing with cartoon  
material to be captured from various analog media like laserdisc or  
35mm (not now, but maybe in the future) and noise is of lesser  
importance - but i do care about unneccessary loss of information. i  
suspect that quantisation would even cause less distortion than  
colorspace conversion. cartoons often exhibit large single-colored  
areas with sharp edges, or surfaces with simple gradients.
compressing and subsampling the color range results in visible  
jaggyness, especially considering the low resolution of laserdiscs.

i did a quick calculation once, don't take my word for it, but a  
blueray disc can easily accomodate several hours of losslessly  
compressed video and audio data in low (ntsc) resolution.

35mm is of course a different matter, to be dealt with later.

just for the record: there is ffv1, which supposedly supports a broad  
range of color spaces and doesn't do quantisation. it also (like  
kakadu) supports only i frames.
if at all possible, i want to compare several codecs in terms of speed
  
and ratio. choosing the best from a handful possibilities is better  
than having to stick with something that might not be suitable at all.





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