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At the NAB show a few weeks ago, James Cameron and Vince Pace announced a new company to assist cinematographers and videographers in the production of 3D movies and TV shows by developing, selling, and leasing 3D camera systems.

 

Cameron feels that in the not-too-distant future, all feature film and TV series production could be mastered in 3D with 2D versions extracted from the digital files. The company has already developed a system for simultaneous 3D/2D production at live events, known as Shadow. It was used during the recent CBS broadcast of the Masters golf tournament.

 

While none of this is earth-shattering news, something Cameron said later during the question and answer period bears mentioning. In response to a question about carrying 3D over conventional broadcast channels, Cameron replied by first describing the side-by-side and top+bottom frame-compatible 3D formats, both of which sacrifice resolution.

 

Side-by-side is used exclusively on 1080i 3D broadcasts, resulting in left eye and right eye images that are anamorphically squeezed into the same video frame. For side-by-side 3D, each image winds up with 960×1080 resolution, while top+bottom images are re-sized to 1280×360. The lost pixels must be interpolated when each frame is anamorphically stretched back to its original size, which is why neither 3D system looks particularly sharp when compared to 3D Blu-ray discs.

 

After Cameron correctly identified side-by-side and top+bottom as being the only practical systems right now for broadcast, he then went on to say, “…full HD 3D would require a doubling of bandwidth, but it’s not necessary right now…you only need full HD for each eye for cinema-sized displays. You don’t need it for home displays. That’s my opinion right now.”

 

You can watch Cameron’s response here – http://www.youtube.com/watch?v=OI8OmPdSfBw&NR=1

 

That comment opened quite a few eyes, particularly mine. Here is the most influential filmmaker of his time when it comes to advanced technology, saying that full HD isn’t needed in the home, and that half-resolution 3D is adequate for now.

 

Really?

 

What about frame-packed 3D Blu-ray discs? I’m sure the Digital Entertainment Group would like to hear Cameron’s perspective on that one. So would any manufacturer of active-shutter 3D TVs. So would any person who just purchased a 3D TV measuring 46 inches and larger.

 

What about passive 3D TVs, which throw away half the vertical resolution from any 3D content? Why would you want to watch less-than-full HD 3D movies and TV shows on one of these sets and just make the problem worse?

 

I would think that Cameron would be strongly advocating for full HD across the board, particularly since one company (Sisivel) already showed a system at NAB 2011 that would accommodate two full-resolution 1280×720 views in a standard 6 MHz channel using H.264 AVC coding. Here’s a picture of what it looks like:

And that is how you pack two full-resolution 1280x720p 3D images into one standard 6 Mhz broadcast...with the help of a little MPEG4 encoding, of course.

The Sisivel system keeps the left eye frame intact; that is the normal 2D view. The right eye frame is broken up into three smaller tiles that are stitched together in the decoder/receiver. It’s not a new trick and is relatively simple to pull off with today’s powerful software and hardware.

 

Granted, ATSC broadcasters do not use MPEG4 encoding. But that’s not the point: Sisivel tried a different approach and came up with a way to handle 720p 3D content without sacrificing any resolution, something that ought to be of interest to ESPN’s 3D content producers who could deliver this format right now over cable and DBS systems.

 

MPEG2 compression systems have also gotten a lot more efficient, perhaps 100% better than they were a decade ago. While it’s not feasible to put a pair of 1920x1080i full-frame signals into a 6 MHz channel, it can be done now with 720p, based on the demos I saw at NAB.

 

No one should ‘settle’ for lower quality 3D if they are simultaneously trying to get the format to take off. There are plenty of sharp technical people out there that are coming up with creative ways to pack multiple HD programs into standard TV channels without compromising image quality. Stay tuned!

Posted by Pete Putman, April 25, 2011 12:50 PM

About Pete Putman

Peter Putman is the president of ROAM Consulting L.L.C. His company provides training, marketing communications, and product testing/development services to manufacturers, dealers, and end-users of displays, display interfaces, and related products.

Pete edits and publishes HDTVexpert.com, a Web blog focused on digital TV, HDTV, and display technologies. He is also a columnist for Pro AV magazine, the leading trade publication for commercial AV systems integrators.