imported_Brian-W

2k is 2048x1566, not 3840x2160. Where did you get this number? Doubling 1920 doesn't = 2k. In fact it's more like 3k, which film scanners don't exist for (it's either 2k or the rarely used 4k)

imported_Brian-W

2k is 2048x1566, not 3840x2160. Where did you get this number? Doubling 1920 doesn't = 2k. In fact it's more like 3k, which film scanners don't exist for (it's either 2k or the rarely used 4k)

Dan Hitchman

If, hypothetically, VC-9 is optimized for about 19 Megabits/sec with 1920x1080p 24 fps (what about video based 30 fps?) then both Blu-Ray and HD-DVD could give us not only the highest video quality at 1080p, but the best audio available today as well.

I would want no less than 1920x1080p optimized with an available ~21x9 anamorphic enhancement for 2.0:1 and wider aspect ratios (easily done using a quality 2k telecine source) and 7.1 channel discrete lossless high resolution audio (MLP would work best since it is already a licensee of the DVD-Forum).

Dan Hitchman

If, hypothetically, VC-9 is optimized for about 19 Megabits/sec with 1920x1080p 24 fps (what about video based 30 fps?) then both Blu-Ray and HD-DVD could give us not only the highest video quality at 1080p, but the best audio available today as well.

I would want no less than 1920x1080p optimized with an available ~21x9 anamorphic enhancement for 2.0:1 and wider aspect ratios (easily done using a quality 2k telecine source) and 7.1 channel discrete lossless high resolution audio (MLP would work best since it is already a licensee of the DVD-Forum).

James Morrow

Sorry about the 2k/4k digital cinema confusion, Brian - my reliable and trusted source couldn't be trusted to be reliable on this occasion. Unluckily, I had checked three other sources for validation and they had all made the same mistake!

Now I've checked over a hundred sources, and everything in the article apart from the 2k, 4k resolution bit seems to be correct, but to clarify:


Film Scanners and Telecine Machines

The "standard" resolution for 2k 35mm film scanners is 4:3 2048 by 1556, although 2048 by 1665 (tall Cinemascope), 2048 by 1792, 2048 by 1566, 2048 by 1536, 1920 by 1445 and 1920 by 1080 are also used - the last recently released by Sony.

The "standard" resolution for 4k 35mm film scanners was set by Kodak in the late eighties at (roughly) 24mm by 18mm, 4:3, 4096 by 3112 pixels. Scans have been carried out up to 4096 by 4096, "tall" Cinemascope is 4096 by 3330, 4096 by 3584 and 4096 by 3072 have also been used. Much more work is now being carried out at 4k, including digital transfers from 65mm IMAX, as near real-time editing tools are becoming available.

Tests have shown that well exposed 35mm film scanned at 6k (4:3 6144 by 4608 pixels) produces clearly better quality than 4k scans - although the improvement over 4k isn't as great as that of 4k over 2k (not surprisingly).

65mm film - such as IMAX material - can currently be scanned at up to 8k resolution (8192 by 6144 pixels), but most IMAX scans are currently performed at 4k resolution.


Digital Cinema Projectors

Digital cinema was launched in 1999 with TI's 1280 by 1024 pixel resolution DLP-based projector. Currently, only around 0.1% of cinema worldwide are digital-compatible, and development is essentially on hold. Even at 1280 by 1024 pixel resolution, a two hour movie takes up around 1TB (uncompressed) - which was a huge amount of data five years ago. HDTV and 2k have roughly double this requirement and 4k four times that again... Kodak has developed a projector based around JVC's 2048 by 1536 DILA modulator, TI are now producing a 2048 by 1080 pixel DLP, JVC are producing limited quantities of a 3840 by 2048 pixel DILA, and Sony have recently announced a 4096 by 2160 pixel resolution LCD-based modulator.


Home Cinema Projectors

A number of current "high definition compatible" projectors for home use are not actually capable of even 720 line resolution - let alone 1080 line. Typically centering around mid-range 1024 by 576 pixel DLPs, they claim compatibility with 720p and 1080i but can't display full resolution data. Others operate at 1280 by 720 pixel resolution progressive scan, and so are ideally suited to displaying 720p material. There are projectors on the market that operate at 1365 by 1024 pixels and now a few at full HD resolution - 1920 by 1080 pixels - but typically interlaced, and 2048 by 1536 pixel resolution. But as the high definition market grows, progressive scan projectors that exactly match high definition 1080 line resolution are likely to dominate, because the difference between interpolated video and a direct one to one mapping pixel for pixel is all too obvious ... So unless you can afford a 1080p projector now I would hold off buying it for a while...

... and now that high definition video approaches, it would be great if Blu-ray also supported high resolution 7.1 or better audio. I know that film is typically stuck at 48/24 at the moment - but a few live music concerts recorded at 1080p24 with 192/24/7.1 or 2822.4/1/7.1 would certainly raise people's awareness of what's possible.

It\'s time we Blu-it...

James Morrow

Sorry about the 2k/4k digital cinema confusion, Brian - my reliable and trusted source couldn't be trusted to be reliable on this occasion. Unluckily, I had checked three other sources for validation and they had all made the same mistake!

Now I've checked over a hundred sources, and everything in the article apart from the 2k, 4k resolution bit seems to be correct, but to clarify:


Film Scanners and Telecine Machines

The "standard" resolution for 2k 35mm film scanners is 4:3 2048 by 1556, although 2048 by 1665 (tall Cinemascope), 2048 by 1792, 2048 by 1566, 2048 by 1536, 1920 by 1445 and 1920 by 1080 are also used - the last recently released by Sony.

The "standard" resolution for 4k 35mm film scanners was set by Kodak in the late eighties at (roughly) 24mm by 18mm, 4:3, 4096 by 3112 pixels. Scans have been carried out up to 4096 by 4096, "tall" Cinemascope is 4096 by 3330, 4096 by 3584 and 4096 by 3072 have also been used. Much more work is now being carried out at 4k, including digital transfers from 65mm IMAX, as near real-time editing tools are becoming available.

Tests have shown that well exposed 35mm film scanned at 6k (4:3 6144 by 4608 pixels) produces clearly better quality than 4k scans - although the improvement over 4k isn't as great as that of 4k over 2k (not surprisingly).

65mm film - such as IMAX material - can currently be scanned at up to 8k resolution (8192 by 6144 pixels), but most IMAX scans are currently performed at 4k resolution.


Digital Cinema Projectors

Digital cinema was launched in 1999 with TI's 1280 by 1024 pixel resolution DLP-based projector. Currently, only around 0.1% of cinema worldwide are digital-compatible, and development is essentially on hold. Even at 1280 by 1024 pixel resolution, a two hour movie takes up around 1TB (uncompressed) - which was a huge amount of data five years ago. HDTV and 2k have roughly double this requirement and 4k four times that again... Kodak has developed a projector based around JVC's 2048 by 1536 DILA modulator, TI are now producing a 2048 by 1080 pixel DLP, JVC are producing limited quantities of a 3840 by 2048 pixel DILA, and Sony have recently announced a 4096 by 2160 pixel resolution LCD-based modulator.


Home Cinema Projectors

A number of current "high definition compatible" projectors for home use are not actually capable of even 720 line resolution - let alone 1080 line. Typically centering around mid-range 1024 by 576 pixel DLPs, they claim compatibility with 720p and 1080i but can't display full resolution data. Others operate at 1280 by 720 pixel resolution progressive scan, and so are ideally suited to displaying 720p material. There are projectors on the market that operate at 1365 by 1024 pixels and now a few at full HD resolution - 1920 by 1080 pixels - but typically interlaced, and 2048 by 1536 pixel resolution. But as the high definition market grows, progressive scan projectors that exactly match high definition 1080 line resolution are likely to dominate, because the difference between interpolated video and a direct one to one mapping pixel for pixel is all too obvious ... So unless you can afford a 1080p projector now I would hold off buying it for a while...

... and now that high definition video approaches, it would be great if Blu-ray also supported high resolution 7.1 or better audio. I know that film is typically stuck at 48/24 at the moment - but a few live music concerts recorded at 1080p24 with 192/24/7.1 or 2822.4/1/7.1 would certainly raise people's awareness of what's possible.

It\'s time we Blu-it...

James Morrow

... but all this talk of high quality digital cinema could become just wishful thinking if Microsoft have their way ...

A wide range of service suppliers, faced with expected increasing public demand for high definition and typical channel bandwidths of 19.4Mbps are busy trying out what they can get away with rather than what they can get - i.e. 1080p24 WMV9 at 8Mbps or lower and using the bandwidth saved to get extra revenue.

Worse than this, although previous digital cinema used uncompressed content (around 1TB for a two hour film), Microsoft is now pushing for WMV in local cinemas at around 8Mbps using IP or DVDs for distribution and Windows PCs to drive the projectors, see:

http://www.microsoft.com/windows/win...cinemaapp.aspx

Now high definition at 8Mbps is very impressive, but it's much lower quality than uncompressed or even mildly compressed content. Digital cinema has the potential to raise quality in the cinema - but not going the direction Microsoft is currently taking it. It seems ironic that just as new optical discs arrive which are capable of supporting much higher standards, what is now being tested in cinemas is of much lower quality...

Even if BD is used for distribution of 1080p24 content compressed to around 20Mbps using WM9, it is still significantly lower quality than uncompressed high definition - cinema quality should be much better than what we have at home, not the same as or even worse than our home systems. The technology exists to make digital cinema even better than current analogue cinema - but if the cinemas go for IP/DVD distribution all we'll end up with is highly compressed high definition video that has nowhere near the transparency of a live high definition feed.

It\'s time we Blu-it...

Lee Scoggins

I find that many theaters are too dim in Ft-lamberts anyway so my presentation of DVDs at home is usually much better. The movie chains are just so loaded with debt that many do not invest in good projection. Often the sound is set too low as well.

My solution? I'm building a home theater in my basement.

no fears alone at night she's sailing through the crowd
in her ears the phones are tight and the music's playing loud
~skateaway

James Morrow

Sounds good, Lee.

... and on the subject of codecs, bitrates and quality, it is often assumed that because MPeg4 and WMV are more modern than MPeg2 they are also capable of producing higher quality pictures than MPeg2. Certainly, at low bitrates their stability and quality compared to MPeg2 is impressive. However, this should not be surprising, because both have been specifically developed to produce the best possible picture quality at low bitrates. However, being designed around minimum bitrates (quantity) rather than quality does not mean that, with minimum bitrates less of an issue, their quality will necessarily be better than a codec that is optimised to use more bits as effectively as possible – or one, such as MPeg2, which for whatever reason is not designed to work at such low bitrates.

In order to achieve their very low bitrates, MPeg4 and WMV have to employ more aggressive compression techniques than MPeg2. One of the main techniques used is motion vector estimation. To understand and see the kinds of artifacts this produces (greatly exaggerated), it is useful to look at video at very low bitrates, such as videophones and many of the transmissions from the recent Gulf war. Instead of a stable, solid world, pieces shimmer and quiver, faces break up and drift back together, and so on. Of course, at higher bitrates these effects are less evident – but they’re there, nevertheless, because motion vector estimation is an intrinsic part of MPeg4 and WMV – supporting the very low bitrates they are designed to achieve.

Tests in the eighties have shown that, under favourable conditions, a human being (and there are a lot of them about) can detect misalignments of around a hundredth of a pixel or less, so this is the kind of precision to which motion vector estimation has to work (under favourable conditions) in order to maintain the illusion of solid, fixed objects that don’t pulsate, shake or quiver, etc.. Favourable conditions include large displays operating at full 1920 by 1080 pixel resolution – i.e. using no interpolation functions. Less favourable conditions include smaller displays and, in particular, displays that use interpolation functions to display 1920 by 1080 pixel material via intrinsically lower resolution devices.

Unfortunately, the vast majority of current “high definition compatible” products are not capable of displaying properly registered 1920 by 1080 pixel resolution material. However, even when running the Microsoft 720p24 8Mbps demos on a 17” 1280 by 1024 pixels display strange pulsing and cogging and jerky movement effects are often visible on vegetation such as trees, scrubland, hedges etc., and there is a tendency for natural objects to look “manmade.” Whilst getting anything even vaguely reasonable at around 8Mbps is impressive, what does this mean at the kind of bitrates that the BD/HD-DVD is capable of – i.e. 24-28Mbps?

Coincidently, in 2003 the Blu-ray Disc Founders [BDF] carried out a detailed study of the performance of full resolution 1920 by 1080 p24 MPeg2 and MPeg4 AVC (part 10) encoded from fine grain film, coarser grain film and digital sources, with bitrates of 7, 12, 15, 20 and 24Mbps. However, they didn’t look into lower resolutions or interpolated images.

Participants included experts from the technical and production divisions of Hollywood studios and from the BDF companies – see the Blu-ray disc technical white paper, part 3 the logical and application specifications, for details, at

http://blu-raydisc-official.org/tecinfo/index.html

In summary, whilst MPeg4 worked at 7Mbps (MPeg2 wasn’t tested), less than a quarter of the viewers were happy with the quality as being sufficient for HD packaged material. At 12Mbps, once again, less than a quarter were happy with material from fine-grained film, although 45% were happy with MPeg2 on coarse-grained film and less than 40% were happy with either codec on largely computer-generated images. At 15Mbps, MPeg4 performed better than MPeg2 with fine-grained film, but still only achieved a less than 40% satisfaction rate, whilst MPeg2 performed better than MPeg4 on coarse-grained film, with a score of 60%, and both scored 60% on largely computer-generated film. Moving up to 20Mbps, MPeg2 was preferred over MPeg4 with all types of images, achieving scores of 60%, 90% and 100% where MPeg4 achieved 55%, 85% and 90%. Finally, at 24Mbps, MPeg2 achieved 100% acceptance, whilst on fine-grained film, MPeg4 only achieved 70%.

The BDF believes that the results show that data rates of 15-20Mbps are necessary to recreate the “feel” of the movie, that MPeg2 encoding technology for HD package media still has room for improvement and that there has been insufficient evaluation of the ability of MPeg4 with high definition images, but that MPeg4 can also improve. It was unclear, however, whether MPeg4 (which was developed for low image resolution and low bit rates) would be able to show a definitive advantage over MPeg2 without losing the high definition quality feel of the image. However, if there are reports of marked improvements in MPeg4 (or WMV) it will be necessary to re-test the technology through subjective evaluation tests, etc..

So just because WMV is impressive at 8Mbps does not mean that it will improve on MPeg2 at high bitrates – although it might. Blu-ray technology as capable of over four hours of high definition material at 24-28Mbps, so ideally we need a codoec optimised for encoding 1920 by 1080 p24 at these data rates. Whether this proves to be WMV or not, the option of longer play modes – particularly in a recording machine – using WMV technology exists. For example, 24Mbps could be a standard play mode [SP], with 16Mbps long play [LP] and 8Mbps extended play [XP]. On extended play, a 50GB Blu-ray disc could record over twelve hours of high definition video at the same quality as a two hour red-laser high definition disc.

It\'s time we Blu-it...

James Morrow

Sounds good, Lee.

... and on the subject of codecs, bitrates and quality, it is often assumed that because MPeg4 and WMV are more modern than MPeg2 they are also capable of producing higher quality pictures than MPeg2. Certainly, at low bitrates their stability and quality compared to MPeg2 is impressive. However, this should not be surprising, because both have been specifically developed to produce the best possible picture quality at low bitrates. However, being designed around minimum bitrates (quantity) rather than quality does not mean that, with minimum bitrates less of an issue, their quality will necessarily be better than a codec that is optimised to use more bits as effectively as possible – or one, such as MPeg2, which for whatever reason is not designed to work at such low bitrates.

In order to achieve their very low bitrates, MPeg4 and WMV have to employ more aggressive compression techniques than MPeg2. One of the main techniques used is motion vector estimation. To understand and see the kinds of artifacts this produces (greatly exaggerated), it is useful to look at video at very low bitrates, such as videophones and many of the transmissions from the recent Gulf war. Instead of a stable, solid world, pieces shimmer and quiver, faces break up and drift back together, and so on. Of course, at higher bitrates these effects are less evident – but they’re there, nevertheless, because motion vector estimation is an intrinsic part of MPeg4 and WMV – supporting the very low bitrates they are designed to achieve.

Tests in the eighties have shown that, under favourable conditions, a human being (and there are a lot of them about) can detect misalignments of around a hundredth of a pixel or less, so this is the kind of precision to which motion vector estimation has to work (under favourable conditions) in order to maintain the illusion of solid, fixed objects that don’t pulsate, shake or quiver, etc.. Favourable conditions include large displays operating at full 1920 by 1080 pixel resolution – i.e. using no interpolation functions. Less favourable conditions include smaller displays and, in particular, displays that use interpolation functions to display 1920 by 1080 pixel material via intrinsically lower resolution devices.

Unfortunately, the vast majority of current “high definition compatible” products are not capable of displaying properly registered 1920 by 1080 pixel resolution material. However, even when running the Microsoft 720p24 8Mbps demos on a 17” 1280 by 1024 pixels display strange pulsing and cogging and jerky movement effects are often visible on vegetation such as trees, scrubland, hedges etc., and there is a tendency for natural objects to look “manmade.” Whilst getting anything even vaguely reasonable at around 8Mbps is impressive, what does this mean at the kind of bitrates that the BD/HD-DVD is capable of – i.e. 24-28Mbps?

Coincidently, in 2003 the Blu-ray Disc Founders [BDF] carried out a detailed study of the performance of full resolution 1920 by 1080 p24 MPeg2 and MPeg4 AVC (part 10) encoded from fine grain film, coarser grain film and digital sources, with bitrates of 7, 12, 15, 20 and 24Mbps. However, they didn’t look into lower resolutions or interpolated images.

Participants included experts from the technical and production divisions of Hollywood studios and from the BDF companies – see the Blu-ray disc technical white paper, part 3 the logical and application specifications, for details, at

http://blu-raydisc-official.org/tecinfo/index.html

In summary, whilst MPeg4 worked at 7Mbps (MPeg2 wasn’t tested), less than a quarter of the viewers were happy with the quality as being suffic