[opendtv] Re: 625 video quality is good enough....
- From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 18 Oct 2004 22:17:24 +0100
Indeed, MPEG2 would struggle, but a truly anonymous transmission system
could carry MPEG4, WM(whatever version) etc, and by thoroughly future proof.
What we need to standardise on is the transport stream, not the scanning
format. Let's try to get it right this time.
----- Original Message -----
From: "Dale Kelly" <res0xtey@xxxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Monday, October 18, 2004 8:25 PM
Subject: [opendtv] Re: 625 video quality is good enough....
> > I'm keen to get to 50p as well, and to leave interlace as a display
> > option,
> > but the best way to get there has to be with a mix of 720p and 1080i so
> > that
> > we can get all our film and film-type production to the viewer at the
best
> > quality. We don't suffer from 2:3 pull-down effects in Europe, film
looks
> > like it should do, even though it lasts 4% less than it should (we're
used
> > to it).
>
> I agree, 50/60P should be the ultimate format when technology can
> accommodate. However, I don't know that it can be done in a transport
> constrained to MPEG2.
>
> I had forgotten about the advantage 50Hz countries have in the film world.
> The "pull down" conversion is one the more valued features of my DTV set.
>
> ----- Original Message -----
> From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
> To: <opendtv@xxxxxxxxxxxxx>
> Sent: Monday, October 18, 2004 11:51 AM
> Subject: [opendtv] Re: 625 video quality is good enough....
>
>
> > NHK are much happier accepting interlaced material than proscan, at
1080.
> > And the downconversion to 625 is trivial because it comes straight from
> > the
> > HDC950 ccu, so interlaced 1080 made most sense for both the BBC and NHK.
> > On
> > both occasions, two productions were made simultaneously (HD and SD),
with
> > two production chains from two mixers driven from one desk. 50i worked
> > just
> > fine for those productions. I can quite see how conversion to 59.94
would
> > be
> > difficult, but NHK were happy to go that way for them.
> >
> > I'm keen to get to 50p as well, and to leave interlace as a display
> > option,
> > but the best way to get there has to be with a mix of 720p and 1080i so
> > that
> > we can get all our film and film-type production to the viewer at the
best
> > quality. We don't suffer from 2:3 pull-down effects in Europe, film
looks
> > like it should do, even though it lasts 4% less than it should (we're
used
> > to it).
> >
> > ----- Original Message -----
> > From: "Dale Kelly" <res0xtey@xxxxxxxxxxx>
> > To: <opendtv@xxxxxxxxxxxxx>
> > Sent: Monday, October 18, 2004 7:26 PM
> > Subject: [opendtv] Re: 625 video quality is good enough....
> >
> >
> >> I should point out that NHK was the co-producer on both occasions, and
> > they
> >> > made no comment on softness. I know that they claim to have a
> >> > spectacularly
> >> > good 50/60 converter in Tokyo, although I've seen no footage through
> >> > it.
> >>
> >> If format conversion is not the culprit, though the resolution loss was
> > akin
> >> to analog material conversion losses I've seen in the past, perhaps the
> > poor
> >> resolution was due to the method of program delivery to Discovery. Any
> >> knowledge of that issue on your end?
> >>
> >> I certainly have no problem with the 1080 25/30 progressive formats,
> > however
> >> do I feel that interlace should be, at best, an interim format.
> >>
> >> ----- Original Message -----
> >> From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
> >> To: <opendtv@xxxxxxxxxxxxx>
> >> Sent: Monday, October 18, 2004 10:20 AM
> >> Subject: [opendtv] Re: 625 video quality is good enough....
> >>
> >>
> >> >I should point out that NHK was the co-producer on both occasions, and
> > they
> >> > made no comment on softness. I know that they claim to have a
> >> > spectacularly
> >> > good 50/60 converter in Tokyo, although I've seen no footage through
> >> > it.
> >> >
> >> > Also, I should point out that part of the argument in Europe over
> >> > *transmission* formats, is that material shot in 1080/50i would be
> >> > converted
> >> > to 720/50p for *transmission*. That strikes me as daft since much of
> >> > the
> >> > 1080 programme production in Europe is in 1080/25psf, so we'd be
> >> > downconverting to 720p ,then frame repeating it. Hardly an efficient
> >> > use
> >> > of
> >> > bitrate.
> >> >
> >> > The EBU's latest statement (R112, IIRC) is that there will be no
single
> >> > *transmission* standard in Europe. It expresses a laudable aim to go
> >> > progressive, but admits that 1080/50p isn't practical yet. The
initial
> >> > position that 720p would be the unique standard has been dropped, and
a
> >> > system is envisaged where individual broadcasters may *transmit* 720p
> >> > or
> >> > 1080/50i ad hoc, perhaps even programme by programme. To me, that
seems
> >> > the
> >> > best compromise until a means is found of sending 1080/50p. It avoids
> >> > unnecessary standards conversion, which has to be a good thing.
> >> >
> >> > None of this refers to programme *production*, only to transmission.
On
> >> > current evidence in Europe, I'd put at least 95% of production being
at
> >> > 1080/50i or 25psf, mostly because much more of the installed base of
> >> > production kit is 1080 than 720, Varicam is the exception.
> >> >
> >> > My 2 pen'orth.
> >> >
> >> > ----- Original Message -----
> >> > From: "Craig Birkmaier" <craig@xxxxxxxxx>
> >> > To: <opendtv@xxxxxxxxxxxxx>
> >> > Sent: Monday, October 18, 2004 3:57 PM
> >> > Subject: [opendtv] Re: 625 video quality is good enough....
> >> >
> >> >
> >> >> At 11:43 AM -0700 10/17/04, Dale Kelly wrote:
> >> >> >You might recall a recent posting suggesting that HDTV might be of
> >> >> >little value in countries using the 625 line system since that
> >> >> >system's quality was likely good enough. My position was, that as
> >> >> >good as that image might be relative to other analog based
> >> >> >standards, it could not compete in quality with true HDTV video
> >> >> >displayed on a 720 or 1080 large screen display.
> >> >> >I'm revisiting this subject only because I saw a very graphic
> >> >> >illustration supporting my argument last evening when viewing the
> >> >> >BBC production of "Last Night at the Proms", on the Discovery HD
> >> >> >channel. This is an excellent program in every way but it was
> >> >> >produced in the 625 (580? DTV) 16X9 format* and compared to other
> >> >> >HDTV programming on the same network was noticeably softer,
> >> >> >particularly on the medium and long shots which are such an
integral
> >> >> >part of that program. Clearly the viewers in Britain would have
> >> >> >noticed and wanted the difference.
> >> >> >
> >> >>
> >> >> There is an obvious explanation, one that has significant relevance,
> >> >> as the ITU considers whether it should approve 720P for
international
> >> >> program exchange, and the inclusion of 720@50P into the
international
> >> >> standards.
> >> >>
> >> >> I cannot reproduce the submission to the ITU directly, however I can
> >> >> paraphrase the key points that the advocates of 720P have made:
> >> >>
> >> >>
> >> >>
> >> >> - Progressive formats make compression work better (one company
> >> >> estimates a 10%to 30% increase in the required bit rate for MPEG 2
> >> >> compressed interlace video as opposed to progressive scan video),
> >> >> preserving bandwidth and providing the best quality to viewers.
> >> >>
> >> >> - Emerging display technologies are progressive friendly and are
> >> >> dominated by 1Mpixel types.
> >> >>
> >> >> - 1280x720 is friendly to modern post-production techniques, which
> >> >> often need to de-interlace source for processing, such as spatial
> >> >> scaling and rotational manipulations.
> >> >>
> >> >> - Conversion from 720p to any other format is simpler and provides
> >> >> better quality because there is no source de-interlacing involved.
> >> >> This is the key to why Dale saw a "soft" picture. In order to
present
> >> >> the content here in the U.S. the original 1080@50i source (thanks to
> >> >> Alan Roberts for this very useful clarification) had to be standards
> >> >> converted from 50i to 60i for broadcast by Discovery Networks. This
> >> >> requires a de-interlacing step, then frame rate conversion, then
> >> >> re-interlacing.
> >> >>
> >> >> Welcome to the realities of standards conversion. It does not get
> >> >> better with HDTV, if we are trying to do frame rate conversions on
> >> >> interlaced source. We are trying to create information that was not
> >> >> sampled, using samples that have been compromised by interlaced
> >> >> acquisition. The net result is that to cover all of the artifacts of
> >> >> the standards conversion, we give up significant resolution.
> >> >>
> >> >> Contrast this with a 50P to 60P conversion or visa versa. We do not
> >> >> need to de-interlace the source, and we have excellent spatial
detail
> >> >> available to do the frame rate conversions. The results are obvious
> >> >> on a progressive display.
> >> >>
> >> >> So bottom line, Dale was seeing the "kinder, gentler, softer" side
of
> >> > 1080i.
> >> >>
> >> >> It's time to get rid of interlace. PERIOD!
> >> >>
> >> >> There is NO GOOD reason for this archaic compression technique to be
> >> >> concatenated with digital compression. This is equally true for
> >> >> SDTV(525 or 625 line), as better results can be obtained with a high
> >> >> quality de-interlacing system, before the source is subjected to
> >> >> MPEG-2 compression. Expecting a cheap de-interlacing chip in a
> >> >> consumer display to do as good a job as a $75K to 100K deinterlacing
> >> >> system is ludicrous. On the other hand, it is dirt simple to convert
> >> >> progressive source for interlaced display using noting more than a
> >> >> convolution filter to remove the details that would cause offensive
> >> >> artifacts on an interlaced display.
> >> >>
> >> >> If we only put progressive source into the DTV channel, the use of
> >> >> interlaced acquisition would
> >> >> disappear quickly, in favor of progressive HD and EDTV acquisition.
> >> >>
> >> >> Regards
> >> >> Craig
> >> >>
> >> >>
> >>
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> >> >
> >> >
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