[opendtv] Re: News: See the Big Picture? Don't Forget to Examine the Fine Print
- From: "John Willkie" <jmwillkie@xxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 4 May 2004 10:00:25 -0700
You are VERY incorrect.
MPEG-2 provides several mechanisms that signal video size ans aspect ratio
(section 1: systems), including a flag that signals a video frame as being
1:1.33; 1:1.78 and 1:2.21, and the size relative size of the picture
elements. Look up the extended segment.
ATSC supports only specific video formats, and extended segment support is
specified.
DVB-SI provides mechanisms -- in addition to MPEG-2 section 1 -- to signal
video frame aspect ratio.
Wanna try again?
John Willkie
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Craig Birkmaier
Sent: Tuesday, May 04, 2004 9:07 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: News: See the Big Picture? Don't Forget to
Examine the Fine Print
At 1:16 AM -0700 5/4/04, John Willkie wrote:
>Ah, but 1:2.21 is in the MPEG-2 and DVB specs. Is that going to be
rendered
>only on 16x9 sets?
MPEG only uses formats as examples. Levels are only constrained by
three factors:
1. Maximum number of samples per line;
2. Maximum number of lines per frame;
3. Maximum number of samples per second.
The specs are aspect ratio agnostic; there is a flag to signal the
actual aspect ratio that is being used.
The DVB and ATSC specs place format constraints on the use of the
MPEG tools. This IMHO was a stupid mistake. At least DVB allows the
satellite guys the ability to use sub line lengths to cram more
channels into their transponders.
Regards
Craig
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