[opendtv] Re: 625 video quality is good enough....
- From: "Dale Kelly" <res0xtey@xxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 18 Oct 2004 12:25:18 -0700
> 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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