How European’s Sisvel Technology compares with the new US broadcast 3D system
Contrary to what many at the press have been preaching since 3DTV was introduced in 2010, 3D is still alive and active in the industry, and many consumers still want to experience 3D at home.
What it should be dead is the approach of inflated advertising and improper reporting of 3DTV as a whole new television set or system that replaces what you have, although it appears that the market and the industry have finally adapted to the idea of considering 3D as what it should have been considered since day one: just a “feature”, one more feature of a good HDTV, to seldom enjoy a 3D movie or sport, then, when the 3D program is over, continue with everyday’s HD viewing. For this reason it is a must to have 3D transmissions backward compatible with HDTV transmissions.
As expected, CES 2013 showed many demonstrations of Ultra HDTV LED and OLED (even in Ultra HDTV resolution, such as Sony’s and Panasonic’s 56” OLED Ultra HDTV prototypes), and there were also 3D demos of the same Ultra HDTV and OLED panels, not to mention the huge 3D wall at the entrance of LG’s booth. Additionally, Stream TV Networks, Hisense, Toshiba and others demo their 1080p and Ultra HDTV auto-stereoscopic (no-glasses) 3D panels as well.
From the point of view of display availability and pre-recorded/theatrical content there has been 3D progress during 2012, and there has been also progress in the work toward new ATSC standard for US’s terrestrial broadcasting of 3D, such as the A/104 Service Compatible Hybrid Coding 3DTV (SCHC) standard approved in December 26, 2012 by the ATSC:
“3D-TV broadcasting service composed of two or more compressed video images, where at least one of them is the legacy 2D-TV image having the same resolution as the production resolution. Elements of Service Compatible Hybrid Coded 3D-TV (SCHC) include Stereoscopic 3D video, audio signals, and ancillary data. Stereoscopic 3D video basically consists of a left view and a right view. In SCHC, left and right views are independently transmitted as separate video elementary streams, one of which is a base view video and the other of which is an additional video. Ancillary data can be caption information, program/channel signaling data, etc. Caption information is transmitted along with the video signal of a bit stream, while signaling data is transmitted via multiplexing….The compression format of the base view video shall conform to MPEG-2 video Main Profile @ High Level  while the compression format of the additional view video shall conform to AVC/H.264 Main Profile @ Level 4.0 or High Profile @ Level 4.0 .”
Is there any other format that would perform the double function of 2D and 3D without impacting image quality on either and still fit within the allotted channel space?
Europe has been in those shoes recently, and the answer is yes. In the US we do not often see what other continents are doing regarding 3D broadcasting, but Europe and Asia showed an accelerated implementation and public acceptance of 3D compared to the US.
A service compatible format announced in December 2010 was launched in the Italian Piedmont region and was backward compatible with 2D HDTV sets using a technique known as 3D Tile Format, which integrates two 720p frames within a single 1080p frame, one 720p image can be tuned by legacy HDTVs for 2D display, the other 720p image is split in 3 tiles when delivered and is reconstructed by a compatible decoder for 3D to be displayed in a 3DTV.
Over the past few years a company named Sisvel Technology (www.sisveltechnology.com) has been actively working and promoting their “3D Tile” broadcasting system that claims to offer a one-for-all solution for broadcasting 3D in HD while delivering the image in a way that is also backward compatible with existing HDTVs.
More recently the company made the 3D Tile format also compatible with near future glasses-free auto-stereoscopic 3DTVs, sharing the same transmission bandwidth of an HD channel, the format was named “3DZ Tile Format”, developed in partnership with Triaxes Vision, a Glasses Free 3D Specialist (www.triaxes.com).
In past articles I mentioned the European 3D broadcasting efforts. I met Sisvel in the past, and again now at CES 2013. We discussed the new 3DZ feature of enabling their transmission for auto-stereoscopic 3DTVs without degrading the current quality of the Tile format by using the remaining space of the 1920x1080 video frame (about 10% or 200,000+ pixels, more below). Currently the Tile format is being used in some areas of Europe.
As with over-the-air broadcasting, distributing 3D over cable, satellite, and IPTV entails higher bandwidth requirements to been able to send two images (left and right eye) using the current HDTV channel space. At the same time the signal is made backward compatible with current 2D HDTVs to avoid having to distribute yet another channel with the HD version of the 3D content. Cable and satellite services in the US are using the top-down or side-by-side half-resolution frame-compatible formats.
New compression algorithms such MPEG-4 allow for the larger 3D data stream to fit into the 6MHz allotted bandwidth space of a current HDTV over-the-air terrestrial transmission that uses MPEG-2, the current compression used for DTV over-the-air broadcasting in the US. The more efficient MPEG-4 can cut in a half the required space and promises an even better image quality.
Sisvel Technology uses MPEG-4 compression to deliver 3D with 1280x720p resolution per eye to new 3DTV sets, it is also backward compatible with legacy HDTVs, and is now also ready for future auto-stereoscopic 3DTVs by also transmitting the extra 3D depth-map.
Auto-stereoscopic 3DTVs use the left eye image and the depth map to create several 3D viewing cones perceived as 3D by several simultaneous viewers (or by a single viewer moving in front of the screen). Auto-stereoscopic systems by 3DFusion, Dimenco, and Stream TV Networks were demo at trade shows, the last one a technology that will be implemented soon by Hisense in their auto-stereoscopic (glasses free) 2K and 4K 3DTV LCD/LED panels, also demo at CES 2013.
Sisvel Technology indicated that although their Tile format is currently based on a 1920x1080 video frame at 50/60fps, it can be adapted to US’s 60i interlaced transmissions as well.
3D content captured as 1080px2 images in 3D the Tile format would be distributed as 720px2 in 3D using a 1080p video frame.
A 3DTV would use both 720p left/right images to display 3D, a legacy HDTV would use the left eye’s 720p image of that 3D transmission to display it as HD (upscaled to 1080p on a 1080p HDTV). An auto-stereoscopic 3DTV would use the left 720p image and the depth map included in the same video frame to display a glasses-free 3D image, all using the existing single HD channel of the broadcaster, cable, or satellite company.
However, a firmware upgrade to current MPEG-4 set-top-boxes (or a new set-top-box) would be required to decode and extract the signal needed by the particular TV.
By delivering the 3D depth-map data into the video frame, rather than having the receiver set-top-box create the depth map on-the-fly from the transmitted left and right images, Sisvel Technology’s method shifts this complex function to the broadcaster’s higher processing power, making the approach relatively less costly than putting the burden in millions of receiving set-top-boxes.
Below is another graph of the Tile format with the depth-map data. Note the 720p left image, and the right image split in 3 pieces, both fitted into the 1080p video frame, and the depth-map data for auto-stereoscopic 3DTVs occupying the bottom right corner of the 1080p video frame.
Of the total 2,073,600 (1920x1080) active pixels of the 1080p video frame, the left/right images of the 3DZ Tile format occupies 1280x720p each (totaling 1,843,200 pixels both together), leaving 230,400 pixels available to store the depth-map (black and white image).
Although the system can still claim HD image quality on the 2D/3D images by using the 720p format, if the original 2D/3D signal was captured as 1920x1080 its higher resolution would have to be downscaled to 1280x720 for transmission, which penalizes the spatial resolution by over 55% (2,073K pixels reduced to 921K pixels) regardless of the frame rate.
I personally may not mind that loss of resolution when viewing an occasional 3D program, and considering that the number of 3D programs are expected to continue to be less numerous than HD programs, I may also accept viewing a 1080p 3D program in downscaled 720p 2D in a 1080p HDTV if the 2D version is not available, but I would not accept all 1080p HD content to be downscaled to 720p if the Tile format would have been always applied to all content at all times.
The 3D Tile system is sufficiently intelligent and versatile to switch to a non-Tiled 1080p HD transmission of film sources that originated from 1080p transfers, properly flagged for the decoder/display to perform the automatic switch of formats on the fly; the transmitted resolution of the image is returned to the full HD definition (1080p HD) because in this case there is no need to share the pixels of a 1080p HD frame with a second view (as it would be needed when the program transmission are in 3D).
Although720p is still considered HD quality and is ideal for fast content due to its fast 60p frame rate, such as ESPN sports, I still prefer the higher spatial resolution of 1080i/p for non-sports content because of its 1920 horizontal pixels (vs. just 1280 of the 720p format) to enjoy the increased pixel detail, especially noticeable in larger screens, which have been increasingly adopted among consumers and will continue to be in the near future, however, 1080i sources are known to be prone to interlaced artifacts on fast moving content.
Posted by Rodolfo La Maestra, February 26, 2013 7:48 AM
About Rodolfo La Maestra
Rodolfo La Maestra is the Senior Technical Director of UHDTV Magazine and HDTV Magazine and participated in the HDTV vision since the late 1980's. In the late 1990's, he began tracking and reviewing HDTV consumer equipment, and authored the annual HDTV Technology Review report, tutorials, and educative articles for HDTV Magazine, DVDetc and HDTVetc magazines, Veritas et Visus Newsletter, Display Search, and served as technical consultant/editor for the "Reference Guide" and the "HDTV Glossary of Terms" for HDTVetc and HDTV Magazines. In 2004, he began recording a weekly HDTV technology program for MD Cable television, which by 2006 reached the rating of second most viewed.
Rodolfo's background encompasses Electronic Engineering, Computer Science, and Audio and Video Electronics, with over 4,700 hours of professional training, a BS in Computer and Information Systems, and thirty+ professional and post-graduate certifications, some from MIT, American, and George Washington Universities. Rodolfo was also Computer Science professor in five institutions between 1966-1973 in Argentina, regarding IBM, Burroughs, and Honeywell mainframe computers. After 38 years of computer systems career, Rodolfo retired in 2003 as Chief of Systems Development from the Inter-American Development Bank directing sixty+ software-development computer professionals, supporting member countries in north/central/south America.