Digital Technology Bringing a 3-D Revival to Theaters

Get out the goofy glasses.

As Hollywood studios and national movie chains search for new ways to get consumers into theaters, they’re turning back to 3-D for their future.

Studios have announced plans to release a record 25 or more 3-D titles over the next two years, including a remake of the hit "The Nightmare Before Christmas" that premieres Sunday(Oct. 19).

Movie theaters, meanwhile, are rolling out 3-D-capable screens in record numbers.

This month, a consortium of theater owners -- including the AMC, Cinemark and Regal chains -- announced an agreement with five Hollywood studios to spend nearly $ 1 billion to install at least 14,000 digital projection systems in theaters across North America over the next several years. That would nearly triple the number of digital theaters in North America.

Despite financing concerns amid the meltdown of the banking system, backers say some of the first digital screens from the agreement could open the first quarter of next year.

"We’re going to push forward as quickly as possible," said Rich Manzione, vice president of strategic development for the Digital Cinema Implementation Partners consortium.

Digital movie projection systems are key to the newest 3-D movie technology. Today’s digital cinema projectors -- the vast majority of which are made by Dallas-based Texas Instruments Inc. -- create 3-D images with a single machine, while old 3-D technology required two projectors running the same film simultaneously.

The new projectors send one image intended for the viewer’s left eye and one for the right. Special polarized eyeglasses prevent the right eye from seeing the left-eye movie, and vice versa. The brain combines the two projections into a single 3-D image.

The reason why Hollywood is hot for 3-D is simple. With big-screen televisions, DVDs, high-definition and pay-per-view movies now commonplace, fewer consumers are going to theaters.

"This gives (theater owners) the chance to provide something that consumers can’t get at home," Manzione said.

It also lets them charge higher prices and reap higher profits. Theaters typically charge a few dollars more for 3-D productions than they do for 2-D productions.

Recent 3-D projects have been well received.

"Journey to the Center of the Earth," billed as the first live-action feature filmed in the latest 3-D technology, opened at No. 3 at the box office in July.

Most notably, theaters that showed the 3-D version of the film sold about three times as many tickets as theaters that showed the film in 2-D.

A 3-D concert video from Walt Disney Studios, "Hannah Montana & Miley Cyrus: Best of Both Worlds" debuted at

No. 1 when it premiered in February.

The top-grossing 3D film of all time came from Austin, Texas filmmaker Robert Rodriguez. His "Spy Kids 3-D," released in July 2003, grossed an estimated $ 197 million worldwide. It cost $ 38 million to make. (NYT)

Dirac PRO

What is Dirac PRO?

Dirac Pro is a version of the Dirac family of video compression tools, optimised for professional production and archiving applications, especially where the emphasis is on quality and low latency (i.e. we avoid the long delay inherent in some of the implementations we use for broadcast or internet applications).

Typical production processes require lossless or virtually lossless compression with low latency. Dirac has been streamlined to meet these requirements.

Dirac Pro is designed for simplicity, efficiency and speed, and intended for high quality applications with lower compression ratios.

Like Dirac it is an open technology, which will work on all the major operating systems, such as Windows, Macintosh or Linux. As it is an Open system, it is easy to import it onto a wide range of hardware, from specialist signal processors to application-specific LSI circuits.

Dirac Pro is capable of being used in post production at resolutions up to 4K with a base layer plus enhancement system, allowing very high quality proxy workflows.

Typical applications may be

• lossless or visually lossless compression for archives,
• mezzanine compression for re-use of existing equipment, such as 1080P 50Hz carried in a 1080I 25 Hz channel
• and low latency compression for live video links.

We can use SD infrastructure to route HD signals by compressing 1.5 GBit/s HDSDI links into 270 MBit/s SDI or SDTI. Likewise, compressing HDSDI signals to be carried on Gigabit Ethernet (at circa 600 MBit/s) would also allow HD working on cheap network infrastructure. DiracPRO introduces minimal artefacts at these levels of compression.

Features

Dirac Pro will support the following techical features, required by professional end-users:

• Intra-frame only (forward and backward prediction modes are also available if required)
• 10 bit 4:2:2
• No subsampling
• Lossless or Visually lossless compression
• Low latency on encode/decode
• Robust over multiple passes
• Ease of transport (can use a range of transport standards including MPEG-2 and SDTI)
• Low complexity for decoding
• Open Specification
• Multiple vendor
• Support for multiple HD image formats and frame rates.

Both Dirac and Dirac Pro are Open Technologies, and the Dirac software source code is licensed under the Mozilla Public License Version 1.1.

The technology of Dirac PRO

The main difference between Dirac and DiracPRO is in the treatment of the final process in compression - the arithmetic coding. Arithmetic coding is processing intensive and introduces delay. These are features that are undesirable in high end production work. The arithmetic coding produces most efficiency savings with highly compressed material. There is little benefit to be gained with the low compression used in top-end production. DiracPRO therefore omits the arithmetic coding.

Applications

There are two specialised applications we have identified as prime targets for DiracPRO.

The first is low-delay compression for live links. This uses a special choice of motion compensation options, avoiding the delay that the most powerful option provides. With low delay, the system can be used for wireless links, within or outside the studio.

The second specialised application is a low compression option designed to deliver nearly lossless coding. This lets us deliver 1080 progressive formats over infrastructure designed for 1080 interlaced.

High-end production is rapidly migrating to high quality 1080 P50/60. But this format requires a higher data rate than the existing 1.5 GBit/s HDSDI infrastructure. The DiracPRO profile supports the transport of these high quality images over conventional high definition infrastructure. This is an evolution of work on Mezzanine coding (aka SMPTE VC-2) which originally used DCT as the transform. Now we are embracing the concept within DiracPRO and using wavelets as the prime compression tool. It is also suitable for quality coding of video for 270 MBit/s links.

Further applications may be lossless or visually lossless compression for archives or mezzanine compression for reuse of existing equipment, such as 1080P 50 Hz carried in a 1080I 25 Hz channel.

For existing standard definition links, compressing 1.5 GBit/s HDSDI links into 270 MBit/s SDI or SDTI would facilitate the use of standard infrastructure for routing HD signals. Likewise, compressing HDSDI signals to be carried on Gigabit Ethernet (at circa 600 MBit/s) would also allow high definition working on a cheaper network infrastructure. DiracPRO gives excellent quality at

Dirac - New Video Compression Technology

Dirac is a prototype algorithm for the encoding and decoding of raw video. It was presented by the BBC in January 2004 as the basis of a new codec for the transmission of video over the Internet. The codec was finalised on January 21, 2008, and further developments will only be bug fixes and constraints^[1]. The immediate aim is to be able to encode standard digital PAL TV definition (720 x 576i pixels per frame at 25 frames per second) in real time; the reference implementation can encode around 17 frames per second on a 3 GHz PC but extensive optimisation is planned. This implementation is written in C++ and was released at SourceForge on 11 March 2004.

An intra-frame-only subset of the Dirac specification, known as Dirac Pro, is being considered for standardisation as SMPTE VC-2^[2].

The codec is named in honour of the British scientist Paul Dirac.

[edit] Technology

Similar to common video codecs such as the ISO/IEC Moving Picture Experts Group (MPEG)'s MPEG-4 Part 2 or Microsoft's WMV 7, it can compress any size of picture from low-resolution QCIF (176x144 pixels) to HDTV (1920x1080) and beyond. However, it promises significant savings in bandwidth and improvements in quality over these codecs, by some claims even superior to those promised by the latest generation of codecs such as H.264/MPEG-4 AVC or SMPTE's VC-1 (which is based on Microsoft's WMV 9). Dirac's implementors make the preliminary claim of "a two-fold reduction in bit rate over MPEG-2 for high definition video"[1], an estimate which would put the design in about the same class of compression capability as the latest standardization efforts of H.264/MPEG-4 AVC and VC-1. MPEG-2 is the previous generation video codec used in the standard DVD format today.

Dirac employs wavelet compression, instead of the discrete cosine transforms used in most older codecs (such as H.264/MPEG-4 AVC or SMPTE's VC-1). Dirac is one of several projects attempting to apply wavelets to video compression. Others include Rududu [2], Snow and Tarkin. Wavelet compression has already proven its viability in the JPEG 2000 compression standard for photographic images.

More About Modulation Error Ratio

Modulation error ratio is digital complex baseband SNR - in fact, in the data world, the terms "SNR" and "MER" are often used interchangeably, adding to the confusion about SNR, especially considering that, as mentioned previously, in the telecommunications world, the terms "CNR" and "SNR" are often used interchangeably.

Why use MER to characterize a data signal? It is a direct measure of modulation quality and has linkage to bit error rate. Modulation error ratio is normally expressed in decibels, so it is a measurement that is familiar to cable engineers and technicians. It is a useful metric with which to gauge the end-to-end health of a network, although by itself, MER provides little insight about the type of impairments that exist.⁹

Figure 13 illustrates a 16-QAM constellation. A perfect, unimpaired 16-QAM digitally modulated signal would have all of its symbols land at exactly the same 16 points on the constellation over time. Real-world impairments cause most of the symbol landing points to be spread out somewhat from the ideal symbol landing points. Figure 13 shows the vector for a target symbol - the ideal symbol we want to transmit. Because of one or more impairments, the transmitted symbol vector (or received symbol vector) is a little different than ideal. Modulation error is the vector difference between the ideal target symbol vector and the transmitted symbol vector. That is,

[Eq. 19]

Figure 13. Modulation Error Is a Measure of Modulation Quality. (Source: Hewlett-Packard)

If a constellation diagram is used to plot the landing points of a given symbol over time, the resulting display forms a small "cloud" of symbol landing points rather than a single point. Modulation error ratio is the ratio of average symbol power to average error power (refer to Figure 14):

MER(dB) = 10log(Average symbol power ÷ Average error power) [Eq. 20]

In the case of MER, the higher the number, the better.

Figure 14. Modulation Error Ratio Is the Ratio of Average Symbol Power to Average Error Power. (Source: Hewlett-Packard)

Mathematically, a more precise definition of MER (in decibels) follows:

[Eq. 21]

where I and Q are the real (in-phase) and imaginary (quadrature) parts of each sampled ideal target symbol vector, and are the real (in-phase) and imaginary (quadrature) parts of each modulation error vector. This definition assumes that a long enough sample is taken so that all the constellation symbols are equally likely to occur.

In effect, MER is a measure of how "fuzzy" the symbol points of a constellation are. Table 4 summarizes the approximate ES/N0 range that will support valid MER measurements for various DOCSIS modulation constellations. The two values in the table for the lower threshold correspond to ideal uncoded symbol error rate (SER) = 10-2 and 10-3, respectively. The upper threshold is a practical limit based on receiver implementation loss. Outside the range between the lower and upper thresholds, the MER measurement is likely to be unreliable. The threshold values depend on receiver implementation. Some commercial QAM analyzers may have values of the lower ES/N0 threshold 2 to 3 dB higher than those shown in the table.

Table 4. Valid MER Measurement Range

Modulation Format	Lower ES/N0 Threshold	Upper ES/N0 Threshold
QPSK	7-10 dB	40-45 dB
16 QAM	15-18 dB	40-45 dB
64 QAM	22-24 dB	40-45 dB
256 QAM	28-30 dB	40-45 dB

Good engineering practice suggests keeping RxMER in an operational system at least 3 to 6 dB or more above the lower ES/N0 threshold.¹⁰ This guideline will accommodate temperature-related signal-level variations in the coaxial plant, amplifier, and optoelectronics misalignment; test equipment calibration and absolute amplitude accuracy; and similar factors that can affect operating headroom. The lower ES/N0 threshold can be thought of as an "MER failure threshold" of sorts. That is, when unequalized RxMER approaches the lower ES/N0 threshold, the channel may become unusable with the current modulation. Possible workarounds include switching to a lower order of modulation, using adaptive equalization, or identifying and repairing what is causing the low RxMER in the first place.

DIY S-video to Composite Video Adapter

Have you been in a situation when your video output device has only S-video output but your TV monitor’s input accepts only composite video input? Then this simple adapter can be very handy. This circuit works with both PAL and NTSC standards.

Short pins 1 and 2 (Y ground and C ground) of the S-video connector and then connect to composite video ground in the RCA connector. Also short pin 3 (luminance) of the S-video connector to the hot pin of the RCA connector. Insert a 470pF capacitor between pin 4 (chrominance) and RCA hot pin. The voltage rating of capacitor can be 10V or more.

The circuit operation is not ideal because impedances are not matched exactly right. But the picture quality you will get may be good enough for emergency situations.