[opendtv] Re: 625 video quality is good enough....
- From: "Dale Kelly" <res0xtey@xxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 18 Oct 2004 15:28:32 -0700
Completely agree.
Unfortunately ATSC's main program channel is constrained to utilising MPEG2
and current receivers support only that format. However, I expect that new
product supporting cable Plug and Play will add support for additional
formats Though by the time 1080P is widely available all this might be
sorted out.
----- Original Message -----
From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Monday, October 18, 2004 2:17 PM
Subject: [opendtv] Re: 625 video quality is good enough....
> 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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