April 3, 2009
by Mark Schubin.
Thousands of us will gather next month in Las Vegas for videography's biggest annual event, the convention of the National Association of Broadcasters (NAB). This year, however, attendance is likely to drop significantly. There's the economy, of course (the American Society of Newspaper Editors and the Magazine Publishers of America are among groups that have cancelled their 2009 meetings), and the notion that magazine columns like this one, blogs, and other news sources will cover the event as well as (or, perhaps, even better than) being there. But then there are these facts about the latest in 3-D videography: It can be 0.7 mm deep and 120 to 170 degrees in duration.
Puzzled? If there's one thing about 3-D on which everyone agrees, it's that it is intended to provide a depth experience significant greater than 0.7 mm. And who measures motion-image durations in terms of degrees? We do know such durations have to be measured in seconds, minutes, or hours. They can also be measured in inches and feet. There's been a correspondence between distance and time in videography ever since the invention of video scanning in the 19th century. In American standard-definition (SD) television, the width of the picture is sometimes said to be between 52 and 53 millionths of a second, because that's how long it took the electron beam in a picture tube to move from the left edge to the right edge of the picture.
The temporal designation made more sense than one using inches, because picture tubes came in different sizes, and it would take the same duration to cross them regardless of width. That's not the case in a 3-D RabbitHole, however. It has no electron beam. For that matter, it has no power cord, battery, wired or wireless connection, or any type of moving part. It nevertheless delivers superb full-color moving pictures in true 3-D, extending both in front of and behind its filmy thinness.
The effect can be mind blowing. But, to fully appreciate it, you have to see it in person. More than 400 people were able to do just that at the 15th-annual Technology Retreat, run by the Hollywood Post Alliance (HPA) in Rancho Mirage, California last month.
Like the NAB convention, at which broadcasters are a minority, so, too, the HPA Technology Retreat, where only a portion of attendees are from the Hollywood post-production community. There were broadcasters; ABC, CBS, the CW, Fox, NBC, PBS, Telemundo, the BBC, and the European Broadcasting Union (EBU) were represented, among others. There were manufacturers -- of computers, consumer-electronics, and professional equipment -- and software developers. There were Hollywood studios and a Bollywood lab. There were academics, consultants, entrepreneurs, journalists, lawyers, rental houses, venture capitalists, and even someone from the National Security Agency. Topics discussed ranged from AXF (the archive exchange format) to zoom-lens elements. And there were take-aways:
Professional videotape will die within five years, but tape will continue to be used into the foreseeable future. Movies should have unlimited loudness range, but producers should consider preemptively limiting it. The shutdown of analog television stations hasn't prevented many viewers from watching TV, but it's screwing up aspect ratios. What is called HDTV isn't necessarily so, but an HDTV signal can provide exit lighting.
Confused? Consider just one topic discussed at the event, 3-D. It was featured in more than a dozen technology demonstrations, seven breakfast roundtables, a panel discussion, and several other presentations.
One of those technology demonstrations featured the RabbitHoles (from RabbitHoles Media). They are film-based holographic prints, less than a millimeter thick but able to show great depth behind and in front of their surface when illuminated with sunlight or ordinary halogen lamps. Unlike other holograms, however, they are full color and full motion, with 1280 frames encoded into the print and sequentially visible as the viewer moves. RabbitHoles Media says the motion duration is about ten seconds, but it actually depends on the speed and distance at which a viewer passes the image, something better measured in angular degrees than in temporal seconds.
RabbitHoles Media might be a name new to you; JVC probably is not. Yet JVC also demonstrated an extraordinary 3-D technology at the HPA retreat, a consumer TV that can take ordinary two-dimensional programming and convert it into 3-D. Other 3-D technology demonstrations included no-glasses-necessary large-screen displays from Alioscopy and Philips (the former with real-time interactivity and the latter also offering tools for positioning graphics in 3-D and for turning 2-D into 3-D).
Then there was that panel, covering everything from shooting to compression, storage, processing, and presentation. You might think shooting 3-D is largely a matter of optics, electronics, and mechanics, but Peter Wilson of HDDC noted that there are also serious artistic issues.
Consider a sporting event shot at a large stadium. Traditional two-dimensional techniques would involve cameras on the periphery of the field with long zoom lenses. Frequent use might be made of a high, wide shot covering the entire playing area.
Unfortunately, none of that really works in 3-D. From the distance of a high, wide camera, a human being would not perceive 3-D, but a viewer of 3-D TV might expect to. Separating two cameras by a significant distance will introduce a sense of stereo, but it becomes the sense that might be experienced by a giant whose eyes are separated by a similar distance; all the athletes will seem tiny and puny.
The ideal shooting plan for 3-D might involve only cameras on the field, running along with the competing teams. Unfortunately, that's probably not ideal for 2-D viewers (or it might already be common practice), not to mention game officials.
Such surprising considerations of technological developments were not limited to 3-D at the event. Consider the shutdown of full-power analog broadcasting. It had been scheduled to take place on February 17, the opening day of the HPA Technology Retreat, but the mandatory date was put off to June 12 before the conference opened.
Nevertheless, many stations did cease analog broadcasting before the broadcasters panel on the 18th, and few problems with reception were reported. Unfortunately, that wasn't the only effect of analog shutdown.
In the past, broadcasters could carry HDTV on their digital transmissions and whatever they thought best on their analog transmissions. A widescreen program might be shrunk to a letterbox format; traditional 4x3 programming could fill the screen.
Without an analog transmission, everyone must deal with the digital. For home viewers receiving the new signals directly via antenna, that's not a technical problem; they can generally adjust their receivers for the image shape that suits them best. Unfortunately, most viewers don't deal with those direct signals, getting their broadcast programming via standard-definition retransmissions over cable TV, direct-to-home satellite services, or telephone-company video services.
Those retransmitters, in turn, cannot afford to have technicians monitoring each broadcaster's programming and changing aspect ratios as appropriate. Instead, they either rely on active format description (not yet widely used) or simply set a downconversion technique once and never change it. If that technique is "center cut," the sides of all widescreen programs get lopped off, even if previously they would have been seen in a letterbox presentation.
As for what retransmitted HDTV looks like, a presentation and demonstration from the EBU was most enlightening. It compared video sequences in "concatenated compression," with one bit-rate-reduction system (such as AVC-Intra, MPEG-2, or JPEG2000) being used when the images are acquired and another being used to disseminate them to homes. The effects of different bit rates were eye-opening. In one sequence involving someone dancing on grass, the grass started dancing, too, at low-enough bit rates.
We've had to learn to deal with many compromises during the history of videography. Shooters of black-&-white video didn't need to worry about the effects of zooming through stripes. Mixers of monochrome TV sound could optimize dynamic range and frequency response for tiny TV-set speakers. Perhaps we'll need to get used to widescreen/narrowscreen and 3-D/2-D compromises as well. But will we need to compromise picture quality for compressed bit rates?
Again, the technology demonstrations proved eye-opening. Several involved new forms of bit-rate reduction. XVD demonstrated its "ultra video compression" system: everything from five streams of 2K movies compressed to two million bits per second (2 Mbps) each, running on a five-year-old "corporate laptop" to mobile video at just 30 kbps, roughly half the maximum data rate of an old dial-up telephone modem. And that brings up the question of attendance at next month's NAB convention.
At the HPA Technology Retreat, Dr. Steve Jolly of BBC Research described and showed partial still images of high-frame-rate video. It was not video intended to be shot at high frame rate and viewed, in slow motion, at a normal rate. It was, instead, video intended to be shot at, stored, processed, and viewed at 300 frames per second.
The notion seems strange. Are there even displays that can present images at that rate? Several speakers said there were. One new consumer TV is said to be capable of 480 frames per second. What about the distribution bit rate? It doesn't need to be increased by a factor of 6 or 12 because less change between frames and sharper frames lead to easier bit-rate reduction.
Unfortunately, Jolly had to end his presentation to those who had not seen his demonstration with a plea for them to trust him about the extraordinary increased sharpness. Even after others in the room who had seen the BBC Research demo backed the sentiment, there was still skepticism.
Contrast that with the technology-demo area, where viewers could see with their own eyes exactly how well JVC's conversion of 2-D into 3-D worked. They could switch between streams on XVD's laptop and evaluate the quality of the bit-rate reduction on a large-screen display. They could ask RabbitHoles Media representatives to change holograms and walk past them at different distances and speeds. They could do all of that because they were there.
In his ProVideo Coalition blog, Adam Wilt wrote of last month's HPA Technology Retreat, "Readers, trust me: If you're into this sort of thing, you gotta be there." What "sort of thing"? In <I>Display Daily,<P> Peter Putman called the event "a 'must attend' for folks engaged in all aspects of media production -- and some who aren't."
Now compare fewer than 100 technology demonstrations, a similar number of presentations, and even a comparable number of breakfast roundtables at the HPA Technology Retreat with much greater numbers of each at next month's NAB convention. Yes, the main product introductions from Avid, Grass Valley, Harris, Panasonic, and Sony are likely to be covered in this publication and others. But what about introductions from companies you never heard of before, a position Avid occupied just 20 years ago?
What about the sort of evaluation of picture and sound quality that you would like to do? Can you tell how JVC's 3-D conversion worked from this article? How about the HPA take-aways noted earlier? Perhaps the analog-television ones were explained here, but how about the others?
Do keep reading this column each month to assist your understanding of the technology of videography. Continue to search the Internet, read product literature, converse with salespeople, and attend local trade-association and professional-society meetings. But if you can learn everything that happened at HPA, IBC, or NAB that way, well, I NV U.
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| COMMENTS (1) | | 04/09/2009 | | Keep a Child Alive is hosting a student produced video PSA contest. Check out the following links for full details.
http://statravelers.com/kca_psa_entries/
http://kcacollege.com/
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