Although this post is somewhat technical, it gives us an overview of the different 3D formats used in the industry.

Side-by-Side

With consumer electronics pundits predicting the success of 3D HDTVs in a big way, consumers have been left confused with regards to the various 3D terminologies being thrown at them by 3D TV manufacturers. One of the common areas of confusion is with regards to 3D content, and how it is delivered to a 3D TV, as well as the various encoding formats that are compatible with different 3D televisions. One of the terms that is being thrown around with regards to the airing of 3D content over cable, is Side by Side 3D. So if you are wondering just what exactly is Side by Side 3D, then this article is perfect for you and will attempt to answer all your questions.

As you may already be aware, almost all 3D TVs that are being released in 2010 rely on the frame sequential 3D display method. However, this doesn’t mean that the input 3D signal to the TV has to be in a frame-sequential format. In fact, pretty much all 3D HDTVs can process 3D signals in a variety of different formats and perform on-the-fly conversion of the incoming 3D video signal into a frame sequential format. While frame-sequential 3D is part of the blu-ray 3D spec, when it comes to airing 3D content over cable/air, Side by Side 3D is proving to be a popular choice. In fact, DirecTV has announced that it will be airing 3D programming by using the side-by-side 3D format. ESPN will also be airing 3D content using a 60fps, 720p side-by-side format.

How Side by Side 3D Works
In side-by-side 3D, a full 1080p or 720p frame consists of two halves on the left and right, with the entire frame for the left eye scaled down horizontally to fit the left-half of the frame, and the entire frame for the right eye scaled down horizontally to fit the right side of the frame. Thus, in the case of 720p content (resolution of 1280 x 720), each frame will actually consist of the horizontally scaled frame for the left eye with a resolution of 640 x 720 and adjacent to it, the corresponding frame for the right eye at the same 640×720 resolution. The image to the right shows what this looks like.

As you might have already noticed, side-by-side 3D results in a halving of the horizontal resolution of each frame intended for the left and right eye. When the 3D ready TV receives this side-by-side 3D signal, it splits each frame to extract the frame for each eye, and then rescales these individual frames to a full HD resolution using upscaling algorithms. It then displays these upscaled individual frames alternately in a frame-sequential manner (see the second image below) that is in sync with your active shutter 3D glasses.

Conversion of side by side 3D content to frame-sequential 3D

You are probably wondering why we would want to settle for a seemingly inferior technique of transmitting 3D content that leads to a halving of the horizontal resolution of the image. The reason that side-by-side 3D is a popular choice for 3D content at the moment is that it uses the same bandwidth as regular HD content, so it can be transmitted in the same way that current HD signals are transmitted. As a result, you won’t need an expensive set-top-box replacement for viewing 3D content. Instead, your cable service providers can upgrade the firmware of the set-top-box to enable the transmission of side by side 3D content to your 3D TV. It should be noted that ESPN has already done some testing with 720p side-by-side content for sporting events and the feedback from initial testers has been extremely positive.

What is Over-Under 3D (or Top and Bottom 3D)?

With 3D TVs and 3D content catching on in a big way in 2010 and leading into 2011, consumers have had to familiarize themselves with a lot of new terminology and jargon specific to 3D display technology and 3D content delivery. One area that is extremely confusing for consumers is that of 3D content formats and how different 3D formats are made compatible with your 3D TV. One of the terms that you have probably come across is the Over-Under or Top and Bottom 3D format. So if you are wondering just what is Over-Under or Top and Bottom 3D, then this article is right up your alley and will do a great job at explaining this concept in simple terms.

The HDMI 1.4 3D format specification allows for a number of different formats for 3D video content. One of the mandatory 3D formats (i.e., the format has to be supported by a 3D TV for it to be HDMI 1.4 compliant) is Top and Bottom or Over-Under 3D. On the other hand, as you may well be aware, almost all 3D TVs currently display 3D content on the screen via Frame Sequential 3D techniques. However, this doesn’t mean that the input 3D signal to the TV has to be in a frame-sequential format. In fact, pretty much all 3D HDTVs can process 3D signals in a variety of different formats and perform on-the-fly conversion of the incoming 3D video signal into a frame sequential format. While frame-sequential 3D is part of the blu-ray 3D spec, when it comes to airing 3D content over cable/air, Side by Side 3D and Top and Bottom 3D are proving to be a popular choice as they are backwards compatible with HDMI 1.3 systems (if they are Frame Compatible versions of these formats) and do not require extra bandwidth for delivery of the 3D video (thus helping with backward compatibility).

How Over-Under 3D a.k.a Top and Bottom 3D Works

The Top and Bottom or Over-Under 3D format consists of a single 1080p (or 720p) frame consisting of vertically stacked sub-frames for the left and right eye, each possessing half the full HD resolution along the vertical axis

In the Over-Under or Top and Bottom 3D format, the video content is encoded in a manner as shown in the adjacent figure. A single frame has a resolution of 1920×1080 (1080p) or 1280×720 (720p) but is divided into two sub-frames, the upper one consisting of the sub-frame meant for the left eye (Labeled L) and the lower sub-frame meant for the right eye (labeled R). As you can tell, the vertical resolution of each sub-frame is halved as a result of the over-under 3D format. In the case of 1080p content, the resolution of each sub-frame is 1920×540 pixels whereas that of 720p content is 1280×360 pixels.

Thus, the downside of this technique is that you lose half the vertical resolution of the image that is seen by each eye and so you are no longer seeing “true HD 3D”. However, the upscaling algorithms in most 3D TVs compensate for this loss in vertical resolution quite well and you can still enjoy good quality 3D content that is transmitted in the top-bottom or Over-Under 3D format.

This version of the Over-Under configuration is commonly referred to as simply by “Top-and-Bottom 3D” or “Over-Under 3D”. However, it should be noted that you can also have an Over-Under configuration where each sub-frame maintains full 1080p or 720p resolution. The Mandatory Full HD 3D (FHD3D) 3D video format that is specified under HDMI 1.4 is such an Over/Under (top/bottom) 3D format where each sub-frame maintains the full 720p or 1080p resolution. Thus FHD3D is the only 3D format that provides true 3D HD video at 24fps. Read our article on the FHD3D format to learn more about it.

The advantage of the Top-Bottom or Over-Under 3D format (with half vertical resolutions) is that each frame still has a total resolution of 1080p or 720p, the same as regular 2D HD content. As a result, the required bandwidth for transmitting the 3D signal, as well as for processing it, remains the same, thus making it much easier to support in current HDMI 1.3 devices. This is why current HD set top boxes can be provided a firmware upgrade by Cable providers so as to enable 3D content without requiring a total upgrade of the box.

How will my 3D TV decode and display Over-Under 3D?

When your 3D ready TV receives this top-bottom or over-under 3D signal, it splits each frame to extract the sub-frame for each eye, and then rescales these individual frames to a full HD resolution using upscaling algorithms. It then displays these upscaled individual frames alternately in a frame-sequential manner (see the second image below) that is in sync with your active shutter 3D glasses.

While Over-Under 3D or Top and Bottom 3D does halve the vertical resolution of the 3D video content, it has the advantage of not requiring extra bandwidth and is helping make 3D content more readily available as cable companies can enable 3D channels without having to spend billions of dollars on expensive set-top box and infrastructure upgrades. This format is primarily of use for providing 3D content over cable/satellite and is also used by some older 3D Ready TVs (before the establishment of the HDMI 1.4 specification). All the new 3D BluRays provide 3D content in the FHD3D format.

Hopefully, you now understand what over-under or top and bottom 3D is. It is just another method to deliver 3D content to your 3D capable flatscreen TV and although it does lead to the halving of the frame resolution along the vertical axis, it still provides an excellent 3D viewing experience. Additionally, it has the advantage of allowing for backwards compatibility with current HD set top boxes.

Sensio 3D format

Sensio’s format is like using the conventional TV format and reworking the image. I could not find anything else on the format but this pdf :

http://www.sensio.tv/11x17_recto-verso_SENSIO_FINAL.pdf

thanks to http://www.best-3dtvs.com for the information.

Hope this post was useful.

• Delicious