TV Technology

Primer: The Principles Of 3D Video And Blu-ray 3D

2:00 AM – May 19, 2010 by Tom Vaughan   http://www.cyberlink.com/stat/3d-support/enu/3d-whitepaper.pdf

Today we’re partnering up with the experts at CyberLink to introduce the principles underlying 3D video, how it is created, and how it’s displayed. Our main interest is Blu-ray 3D, so we’ll be exploring the tech your 3D-enabled home theater might include.

Tom Vaughan is the director of business development for CyberLink, developers of the leading Blu-ray player software, PowerDVD. He is responsible for marketing, strategic relationships, and new business development in the US. When the DVD format first emerged, Tom was responsible for developing the DVD authoring and mastering processes, managing the production of some of the first commercial DVDs in the US. Tom holds a B.S. in Electrical and Computer Engineering and an M.B.A. from Drexel University.

What Is 3D?

3D is an abbreviation for “three-dimensional.” Objects in the real world can be measured in three dimensions; for example, by measuring the length, width, and height of an object. When we look at objects in the real world, we can see the width and height of an object (the two-dimensional view of the object), but we can also perceive the depth and distance of the object.

We see the world with our two eyes. Because each eye is in a slightly different location, each sees a slightly different perspective of whatever we are looking at. We don’t normally think about these two different views, but if you close one eye at a time, you will see the image that each eye sees. Notice how much different nearby objects appear from the view of each eye.

Although each eye sees a different image, we don’t perceive two images. In a process called stereopsis, our brain combines the view from each eye into a single picture, and the combined image includes three-dimensional objects and depth perception. The word “stereopsis” is from the Greek words stereo, meaning “solid,” and opsis, meaning “sight.”  Stereopsis was first described in 1838 by Charles Whetstone, but scientists and artists have been fascinated with three-dimensional perception for many centuries.

While most of the population can see 3D, a small percentage of the population (estimates range from 3 to 15%) suffers from some stereoscopic vision impairment. Depending on the quality of the 3D presentation, this population will see no 3D effect or limited 3D depth perception. There are a number of possible causes for this, from decreased vision in one eye, to the loss of the ability to point both eyes inward towards nearby objects.

Humans (and most predators) have two eyes in the front of their head. This “binocular vision” improves depth perception, letting a hunter estimate the distance to its prey. 

In addition to stereoscopic vision, depth perception also comes from a number of monocular depth cues (depth perception cues that can come from only one eye, or more precisely, that come from the 2D version of the picture that you see). These cues are important to good 3D video, as your brain will expect your stereoscopic perception to closely match your 2D perception of the scene you are viewing.

Monocular cues include:

Your memory of the shape and size of different objects: combined with the relative size of the image you see, this lets you perceive the distance to that object. For example, in the photo below, if you are familiar with the size of the bricks that the squirrel is standing on, you can quickly perceive the size of the squirrel, and your distance to the squirrel.

Perspective: Objects at greater distances appear smaller than near objects. Parallel lines appear to converge as distance increases. This effect is obvious as you stand on a straight road or path and look down the road, or when you look up at a tall building.

Occlusion (interposition): If we see two objects, where the first object is blocking part of a second object, we recognize that the first object is closer. In the photo below, you can tell that the tree in the center is closer than the building because it is blocking your ability to see part of the building. Occlusion helps us estimate the relative distance of objects in the photo.

Shadows and Highlights: Help us to see objects that are raised above or recessed into a surface. In the photo above, we can see that there are bumps on the tree trunk, thanks to the shadows and highlights.

Parallax: As we move, we notice that the relative position of nearby objects changes more than far objects. In the photos below, as a virtual camera moves from left to right across a virtual three-dimensional scene, you can observe that objects that are closer appear to move (right to left) more than far objects.

the Motion Picture Experts Group (MPEG) have taken advantage of this fact to reduce the overall bit rate and file sizes for stereoscopic 3D. A new Video Codec was developed, based on the Advanced Video Codec (AVC, also known as H.264), called Multi-View Codec (MVC). Blu-ray 3D uses MVC video encoding, which provides for very high picture quality with an overhead (versus standard Blu-ray) of 50%. While the peak bit rate for standard Blu-ray movies is 40 Mb/s, the peak bit rate for Blu-ray 3D is 60 Mb/s. 

Blu-ray 3D MVC is encoded as a primary video stream (for one eye, or for 2D playback) and a dependent video stream for the other eye. The dependent video stream references the objects in each frame of the primary video stream, encoding only the differences.

Blu-ray 3D has enhanced graphics capabilities, allowing for 3D menus and subtitles positioned in 3D video. Menu and subtitle graphics and text can be defined to appear on a plane that is offset from the screen. This plane can be defined to be either closer to or farther away from the viewer. This depth offset is accomplished by shifting the text or graphics horizontally by an equal and opposite amount over the video stream for each eye.

Upgrading to Blu-ray 3D

To enjoy Blu-ray 3D titles, consumers must upgrade their PC or their home theater system. There are several components that are needed:

  • A 3D-capable display (TV, desktop display, or notebook PC display)
  • 3D glasses compatible with your display
  • A PC with Blu-ray 3D player software, or a (set-top) Blu-ray 3D player

In order to choose the right solution, there are some important things to consider for each of these components.

Blu-ray 3D TVs or Displays

The Blu-ray 3D format does not specify the 3D display technology. This allows consumers to choose the 3D display technology that best meets their needs. At the high-end, consumers will likely select true 120 Hz frame-sequential displays that use LC active shutter glasses. Less expensive systems can be configured using polarizing displays and glasses.

Blu-ray 3D Players

Blu-ray 3D players can be implemented on a PC using Blu-ray player software, or as a dedicated hardware solution, otherwise known as a set-top Blu-ray player. Sony’s PlayStation 3 (PS3) game consoles, for example, are expected to get a firmware upgrade in the summer of 2010, providing support for Blu-ray 3D. Several set-top Blu-ray 3D players have been announced, and some are already available.

Blu-ray 3D on a PC

Another way to enjoy Blu-ray 3D is to purchase Blu-ray 3D player software like CyberLink’s PowerDVD 10 Ultra. PCs can be connected to a 3D-compatible display, and later, to a 3D-capable TV. In other words, a PC with Blu-ray player software is a true Blu-ray player, capable of all of the same functions as a set-top Blu-ray player. In addition, a Blu-ray 3D-capable PC offers many capabilities that fixed function hardware devices don’t:

  • Enjoy 3D Games; over 400 game titles can be played in 3D
  • Access and enjoy Internet video from any Web site, including 3D video
  • Play 2D and 3D video files from almost any source (DV, HDV, AVCHD, AVI, WMV, MOV, etc.)
  • View 2D and 3D photos
  • Support for cable or satellite TV content through solutions such as DirecTV2PC
  • Support for premium, protected video (Amazon, iTunes, etc.)
  • Video enhancement, such as CyberLink TrueTheater HD, TrueTheater Motion, and TrueTheater Lighting
  • Access and play music, video, or browse photos on your home entertainment system
  • Use other 3D software, such as CAD, 3D animation, or 3D solid object modeling software

Blu-ray 3D capability will be available in every PC form factor, including:

  • Notebook PCs (with true 120 Hz sequential-frame displays)
  • Desktop PCs and displays
  • Home Theater PCs

 

Should I upgrade my TV, or my PC?

Ultimately, you’ll want to watch movies on the largest screen that you can afford.  Several 3D TV models are available today, and more will be available later this year.

This year, 3D TVs are going to be relatively expensive. Typically, the replacement cycle for TVs is between five and 10 years. Consumers who have recently purchased a new large-screen TV may be reluctant to upgrade to a new 3D TV right away. It is likely that consumers will add 3D capability at some point in the future when they otherwise choose to upgrade or replace their TV. Of course, this decision depends on many factors, such as the availability of Blu-ray 3D titles, 3D TV channels, and other 3D video content.

Replacement cycles for notebook PCs, and upgrade cycles for desktop PCs are much faster. Enthusiasts may upgrade their desktop PCs every year. It will be easy to add 3D video decoding and display capability when upgrading or replacing a PC. For these reasons, we think that the installed base of 3D video-capable PCs will vastly outnumber 3D capable TVs in the next few years.

Decoding Blu-ray 3D on a PC

While quad-core CPUs can support software decoding of 3D Blu-ray, the optimal solution includes a discrete graphics card or integrated graphics solution capable of decoding Blu-ray 3D in the GPU. The latest-generation graphics processors, including Nvidia’s GeForce GT 240, GT 340, GT 330, GT 320,  GTX 470, GTX 480 graphics cards, and GeForce 300M-series mobile graphics, and systems with Intel Core processors with Intel HD graphics (Core i3, Core i5, and Core i7 Mobile) support dual HD video stream decoding. Blu-ray 3D video decoding solutions can be expected for ATI Radeon 5000-series graphics in the future.

Blu-ray player software utilizes these modern graphics processors to decode Blu-ray 3D MVC, resulting in very low CPU utilization and flawless video performance.

Connecting To A PC display

Full-quality 120 Hz frame sequential 3D video is only supported through a dual-link DVI connector (for Nvidia 3D Vision-compatible displays), or (soon) through a High Speed HDMI cable to a HDMI 1.4-compliant display.

HDMI 1.4 specifies support for a number of 3D video signal formats, including full-frame, dual-stream 3D, where both the left and right video frames are packed into a single stereo frame, with the left eye picture on top of the right. HDMI 1.4 stereoscopic frame packing supports 1080p at 24 frames per second, or 720p resolution at 50 or 60 frames per second.

HDMI 1.4 also defines 3D signals compressed into standard 2D video formats, including side-by-side and over/under. Polarized displays can be connected to a PC using standard DVI or HDMI 1.3 connections.

Connecting to a 3D TV

Full-quality 120 Hz frame-sequential 3D video (such as Blu-ray 3D) is only supported through a High Speed HDMI cable to a HDMI 1.4-compliant TV.

Nvidia has announced that some 3D Vision-compatible graphics cards and systems will be software-upgradeable to provide HDMI 1.4 stereoscopic output through a forthcoming 3DTV Play software

Home Theater

Why NTSC and PAL Still Matter With HDTV

How Digital TV and HDTV Are Linked to Analog Television Standards

By Robert Silva, About.com Guide

A lot consumers around the World assume that, with the introduction of Digital TV and HDTV, the old barriers to a universal video standard have been removed. However, this is an incorrect assumption. Despite the fact that video is going digital, the fundamental difference between video standards that exist currently, Frame Rate, is still the foundation of the new Digital TV and HDTV standards.

What Frame Rate Is

In video (both Analog and HD), just as in film, images are displayed as Frames. However, there are differences in the way the frames are displayed on a television screen.

How Frames are Displayed in Analog Video

Lines and Pixels

A television or recorded video image is basically made up of scan lines or pixel rows. Unlike film, in which the whole image is projected on a screen at once, a video image is composed of lines or pixel rows displayed across a screen starting at the top of the screen and moving to bottom. These lines or pixel rows can be displayed in two ways. The first way is to split the lines into two fields in which all of the odd numbered lines or pixel rows are displayed first and then all of the even numbered lines or pixel rows are displayed next, in essence, producing a complete frame. This process is called interlacing or interlaced scan.

The second method, used in flat panel TVs and computer monitors, is referred to as progressive scan. Instead of displaying the lines in two alternate fields, progressive scan allows the lines to displayed sequentially. This means that both the odd and even numbered lines are displayed in numerical sequence.

NTSC and PAL

The number of vertical lines or pixel rows dictates the capability to produce a detailed image, but there is more. It is obvious at this point that the larger the number of vertical lines or pixel rows, the more detailed the image. However, within the arena of analog video, the number of vertical lines or pixel rows is fixed within a system. The current major analog video systems are NTSC and PAL.

NTSC is based on a 525-line or pixel row, 60 fields/30 frames-per-second, at 60Hz system for transmission and display of video images. This is an interlaced system in which each frame is displayed in two fields of 262 lines or pixel rows, which is then combined to display a frame of video with 525 lines or pixel rows. NTSC is the official analog video standard in the U.S., Canada, Mexico, some parts of Central and South America, Japan, Taiwan, and Korea.

PAL is the dominant format in the World for analog television broadcasting and video display and is based on a 625 line or pixel row, 50 field/25 frames a second, 50HZ system. The signal is interlaced, like NTSC into two fields, composed of 312 lines or pixel rows each. Since there are fewer frames (25) displayed per second, sometimes you can notice a slight flicker in the image, much like the flicker seen on projected film. However, PAL offers a higher resolution image and better color stability than NTSC. Countries on the PAL system include the U.K., Germany, Spain, Portugal, Italy, China, India, most of Africa, and the Middle East.

For more background information on the PAL and NTSC analog video systems, check out my article: An Overview of Worldwide Video Standards1.

DigitalTV/HDTV and NTSC/PAL Frame Rates

Although the increased resolution capability, digital format broadcasting, and high definition video software content standards are a step up for consumers, when comparing HDTV to analog NTSC and PAL standards, the fundamental common foundation of both systems is the Frame Rate.

In terms of traditional video content, in NTSC-based countries there are 30 separate frames displayed every second (1 complete frame every 1/30th of a second), while in PAL-based countries, there are 25 separate frames displayed every second (1 complete frame displayed every 25th of a second). These frames are either displayed using the Interlaced Scan2 method or the Progressive Scan3 method.

With the implementation of the Digital TV and HDTV, the foundation of how frames are displayed still have their roots in the original NTSC and PAL analog video formats. In soon-to-be former NTSC-based countries, Digital and HDTV are implementing the 30 Frame-per-second frame rate, while soon-to-be PAL-based countries are implementing a 25 Frame-per-second Frame rate.

NTSC-Based Digital TV/HDTV Frame Rate

Using NTSC as a foundation for Digital TV or HDTV, with the frames are displayed as an interlaced image (1080i), each frame is composed of two fields, with each field displayed every 60th of a second, and a complete frame displayed every 30th of a second, using a NTSC-based 30 frame-per-second frame rate. If the frame is in the progressive scan format (720p or 1080p) it is displayed twice every 30th of a second. In both cases, a unique high definition frame is displayed every 30th of a second in former NTSC-based countries.

PAL-Based Digital TV/HDTV Frame Rate

Using PAL as a foundation for Digital TV or HDTV, with the frames are displayed as an interlaced image (1080i), each frame is composed of two fields, with each field displayed every 50th of a second, and a complete frame displayed every 25th of a second, using a PAL-based 25 frame-per-second frame rate. If the frame is in the progressive scan format (720p or 1080p) it is displayed twice every 25th of a second. In both cases, a unique high definition frame is displayed every 25th of a second in former PAL-based countries.

Final Take

In the final analysis, Digital TV and HDTV, although a leap forward in technology implementation, in terms of what you actually see on the screen, with reference to increased resolution and detail, still has roots in 50-plus year-old analog video standards. As a result, there are, and will be, for the foreseeable future, differences in Digital TV and HDTV standards in use throughout the World, which reinforces the barrier to true Worldwide video standards for both the professional and the consumer.

For a more indepth look at Video Frame Rate differences, and how they are implemented in the Digital TV and HDTV environment, also check out my article: Video Frame Rate vs Screen Refresh Rate4.

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