[opendtv] Chroma Formats, P versus I, and Resolution Issues

  • From: "Tom McMahon" <TLM@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 15 Dec 2004 14:24:16 -0800

I am not necessarily disagreeing with anyone here but let me just say that:

* The primary reasons we just added the 4:4:4 Profile to the H.264/AVC FRExt 
Amendment were 1) To support non-YCbCr color spaces
(like RGB, SMPTE XYZ' or multispectral imagery) where chroma subsampling simply 
makes no sense and 2) to support the post industry
where you are doing many generations of postprocessing and can't afford all the 
chroma up/downconversion each time.  (Yes, there is
going to be I-frame and other forms of compression in post.)

* The primary justification for including the new H.264/AVC 4:2:2 Profile was 
for interlaced applications.

* After spending a few years looking at the highest possible quality 
progressive D-Cinema imagery on the biggest screens with the
best (2K black chip) projectors going thru both 4:2:0 and 4:4:4 codecs, I see 
no reason not to use 4:2:0 chroma format for
compression (so long as the imagery is progressive).

-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On 
Behalf Of Tom Barry
Sent: Wednesday, December 15, 2004 2:00 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Why Europe should choose 720P for HDTV

As that's two posts correcting me now I guess I better clarify my sloppiness. 
The "it" that I was claiming we couldn't currently see
was the full glory of 4:4:4 1080p and not referring to seeing the difference 
between the lower resolutions bandied about.

- Tom

John Shutt wrote:

> 3 out of 4 programs on PBS's HD schedule are actually widescreen SD 
> upconverted to 1080i.  The difference is very noticeable.
> John Shutt
> ----- Original Message -----
> From: "Doug McDonald" <mcdonald@xxxxxxxxxxxx>
>>>Just because we couldn't see it on almost all current displays (1080i 
>>>  720p fixed) doesn't mean we shouldn't do it.
>>That last is false ... it CAN be easily seen, and noticed, as it is 
>>actually AVAILABLE TODAY, almost every day. It is visible on Fox OTA 
>>TV. It is clearly inferior to true HD 720p.

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