[x264-devel] I444 support

[List, Peter]

> Hi,
> I have been monitoring this list for quite some time now.  A long time
> ago I mentioned that I was interested in high 4:2:2 and High 4:4:4
> support.  Peter List recently mentioned that H.264 was not suitable
for
> hi quality encoding with low compression. 
> ...

Hi James,
I think you got me a little wrong!

Gregor wrote:
> > i'm working on a system to archive old media digitally, and I want
to 
> > do that with as little data loss as possible.
> > 
> > as h.264 offers very good compression ratios and can operate in a
no- 
> > quantisation mode (qp=0), I want to use that, if possible.

I was simply trying to raise some doubt, that compressing video at qp=0
and as he said with "as little data loss as possible" was such a good
idea. But if he really wanted to he also might consider JPEG2000...

On the other hand:
As far as I know, one of the reasons for DCI to decide for JPEG2000 and
against H.264 was the inability of H.264 to produce COMPLETELY
transparent quality at low compression rates at that time. Because of
that phenomena the gains of temporal prediction in H.264 were to a large
extend eaten up by the necessity to reduce qp more than expected to gain
the same visual quality than JPEG2000. 

This, and also concern from the BlueRay and/or HD-DVD bodies led to the
decisions to sort of invalidate MainProfile and replace it with
HighProfile.  
HighProfile is basically equal to MaiunProfile, but contains two
specific methods to enhance the picture quality at very high data rates.
These are "8x8 transform" and "quantization scaling matrices".
Still, HighProfile might not have become perfect in that respect.

Regards
Peter