Home Theater and Projectors

First Blog – Moving to 3D

Greetings to all existing and future home theater owners that have made the decision to use front projection at the means of achieving the cinema experience in their own home.  For my first blog, as well as the next several here at Projector Reviews, I have decided to focus a little on the history and more on the technology for bringing 3D into the consumer home theater environment.  Pete Connolly’s “The Art of Gaming” blog will cover 3D gaming while my focus will be on 3D for viewing movies and video programming.

 

Over the next several blogs I will be talking a little about the history of 3D video with some discussion of how 3D video has evolved into its current state.  I also plan to get into some the technical aspects of 3D video with discussions of the alternative 3D approaches for providing consumers with 3D in their projector-based home theaters.  My focus will not be limited to just 3D-ready projectors but also to projection screens, 3D glasses, video processing and to some extent to 3D sources. 

 

To start off this first blog I would like to summarize where we are with the HDMI version 1.4a standard for 3D video.  The HDMI version 1.4a specification was released on March 4, 2010 and includes a section on “Extraction of 3D Signaling” that defines the 3D formats that are mandatory for 3D displays. Note that there are a number of 720p DLP projectors being sold as being ”3D Ready” that do not have HDMI 1.4a input(s) and do not support the 3D video formats required by that specification.   Any 3D display/projector that claims to be certified to HDMI 1.4a must accept all of the mandatory 3D signal formats (listed below) at their HDMI input then internally apply video processing to put the 3D video into a format appropriate for that specific display. Therefore, the 3D video source (e.g., Blu-ray 3D disc player) is not required to adapt its output signal format to the unique capabilities of the connected 3D display nor is the 3D source device required to support more than just one of the approved 3D signal formats. Note that the rules for which 3D formats are required to be supported applies only to those sources and displays that claim to be compliant with the HDMI 1.4a specification. The Blu-ray 3DTM specification (released in December 2009) specifically requires support for the Frame Packing 1080p/24 and 720p/60 formats as defined by the HDMI 1.4 spec. Below is a brief summary of the mandatory 3D video formats that are defined by the HDMI 1.4a specification. There are 3 basic formats defined (in table 8-15 and associated figures and text of the HDMI 1.4a spec.) and then there are specific resolution and frame rate variations required/allowed under each.

Frame Packing 3D Format (Blu-ray 3D required full resolution formats)  

  • full 1080p resolution for each right/left images with refresh rates of 23.98/24 Hz
  • full 720p resolution for each right/left images with a refresh rate of 50Hz* or 60Hz.

The Frame Packing structure used for delivering full resolution 1080p 3D video at 24 frames per second (for each the right and left image streams) is illustrated in the figure below:

 Note:    Frame Packing is capable of placing two full resolution HD images into one “super sized” frame as shown above for transmission across HDMI. Frame Packing provides full resolution 3D and when used for 1080p 3D video, the right and left images are placed one above the other into a “super sized” frame that is 2205 pixels vertical by 1920 pixels horizontal with a 45 x 1920 pixel active blanking area separating the two images.

 

Side-by-Side 3D Format – (e.g., satellite or cable 3D broadcast)

  • half horizontal resolution 1080i (i.e., 960h x 1080v pixels) for each right/left image with refresh rates of 59.94/60 Hz or 50 Hz*.

Top-and-Bottom 3D Format – (e.g., – satellite or cable 3D broadcast)

  • half vertical resolution 1080p (1920h x 540v pixels) for each right/left images with refresh rates of 23.98/24 Hz.
  • half vertical resolution 720p (1280h x 360v pixels) for each right/left image with refresh rates of 59.94/60 Hz or 50 Hz*.

 

Note:    All 3D displays conforming to the HDMI 1.4a spec. must accept 3D signals with a 23.98/24 Hz refresh rate as well as either 50Hz (e.g., Europe) or 60Hz. (e.g., North America) refresh rates for all of the mandatory 3D signal types as listed above. However, the actual resolution and refresh rate the 3DTV uses to display the 3D images to the viewers is entirely up to the specific 3DTV design.

 

Please post you comments and/or suggested future discussion topics.

 

RonJ  (Ron Jones)

News And Comments

  • Devin

    Ron, I asked these questions to Art and Pete, wanted to get your input on the best type of screen for gaming. I am looking at the Epson 8700UB. Am I going to notice a big difference from my panasonic plasma? (brightness, color saturation,etc.) I am looking forward to a much bigger screen (110″ with the projector being about 11-14 feet away) but dont want a huge PQ trade off for gaming in terms of the brightness and color. I also spoke with Art about the screen, leaning toward a carada brilliant whtie 1.4 gain screen vs a regular Carada 1.0 screen. Need something that is good for both movie watching, TV, and gaming. Any suggestions?

    • http://www.projectorreviews.com/members/rjon197/ rjon197

      The “best” screen for you specific situation will depend on several factors including:

      Is the room light controlled for watching movies, for watching TV and/or for gaming?

      What is the room layout and are the walls and ceiling painted a dark color or light color?

      If there are windows or room lights that cannot be controlled during viewing, where are they located relative to the screen?

      Will the projector ceiling mounted near the ceiling or do you have the option of mounting the projector near eye level?

      Do you plan on having your projector calibrated for accurate colors and grey scale for movie viewing?

      Are you looking a fixed frame screen, a manual pull-down screen or an electric drop down screen?

      What price range are you look for?

      Assuming you have a fully light controlled room and are flexible for the mounting locations for the projector then for viewing movies at the nominally recommended 16 foot lamberts (FL) for the light level off of the screen you can trade-off screen size for screen gain. The Projector Reviews test of the Epson 8700UB measured the projector light output at about 500 lumens in THX mode. A 16 x 9 screen with a diagonal size of 100 inches with a gain of 1.0 would result in 16.9 FL. Likewise moving up to a larger 120 inch screen with a higher gain of 1.4 would produce a similarly bright image at 16.4 FL. Also moving the projector to near the shortest projector-to-screen throw distance permitted for the selected screen size will increase image brightness.

  • Mike

    Ron, Thanks for the article I have not updated my projector to 3D yet. This has me wondering if I will have to update my cabling to HDMI 1.4 or will my current HDMI cabling 1.3 work with a 3D formatted projector…Thanks for your input.

    Mike

    • http://www.projectorreviews.com/members/rjon197/ rjon197

      There really is no such thing as a “HDMI 1.4a Cable”. The official labeling for HDMI cables changed more than a year ago such that HDMI cables are now designated as either “Standard Speed” or “High Speed”. The “High Speed” HDMI cables are the ones that can support the data rates required by 3D and these also have the same bandwidth as what was required to support the more demanding high definition formats first introduced with HDMI 1.3 (such as 1080p/60 video with lossless HD audio). So the bottom line is if your existing HDMI cables were sold under the old labeling as HDMI 1.3 Category 2 then they support the same data rates as what are now called “High Speed” HDMI cables and should work just fine for 3D video. Even some HDMI cables, especially in shorter lengths, sold either as HDMI 1.3 Category 1 cables or as “Standard Speed” HDMI cables may in fact have enough bandwidth to support 3D video signals, but you would need to test each one yourself to find out as it is a hit or miss proposition.

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