HDTV Glossary

HDTV format of 1080 interlaced visible lines of 1920 total pixels each in 16:9 aspect ratio. 1080i is per frame (540 lines x two fields) at 30 fps, and the HD format is commonly used since 1998. See DTV.

HDTV format of 1080 progressive visible lines of 1920 total pixels each in 16:9 aspect ratio. 1080p is per frame at either 24fps or 30 fps. 1080p/60fps is not one of the 18 ATSC formats but new displays introduced since 2005 are able to display in that format. 1080p/24fps should be ideal for the transfer and broadcast of 24 fps film-based material, but it is not used at the present broadcasting. However, should it be used, objectionable flicker would require the 1080p/24fps to be converted to either progressive 1080p/60 fps or interlaced 1080i/30fps (60 fields per second).

If the signal were to be converted to the higher 1080p/60fps, it would also require a CRT based video projector with a fast raster (67.5kHz, double the 33.75kHz of 1080i/30fps) to been able to synchronize to the signal and display it as 60pfs. The same (fast raster) requirement would apply if the 1080p/60fps were obtained from line doubling a 1080i/30fps broadcast program using a scaler/line doubler processor. Some fixed pixel displays released on the first generation/s of 1080p HDTVs capable of displaying 1080x1920 are not actually able to 'accept' a 1080p/60fps signal from an external source. In 2006, such a source was introduced: Blu-ray Hi-Def DVD.

Technique used to display/transfer film based content to video. Film is shot at a rate of 24 frames per second, when projecting it on a motion picture cinema theater screen any visible flicker is minimized by opening the film shooter of the film projector twice for each frame, so viewers actually see 48 frames per second.

Interlaced video systems display at 30 frames per second (in 60 interlaced fields for 480i NTSC or 1080i HDTV). Simply transferring each of the 24 film frames onto one video frame would result in a video version of the film running about 25 % faster than intended; this is solved by repeating some of the images to restore the proper speed of the film when viewed as video. Telecine machines are used to transfer film to video to produce masters.

Although DVD is a NTSC interlaced video media (480i 60 fields x second), frame content that originates from film is actually stored as 48 fields rather than 60 fields to save space. The original 24 frames of the film source can easily be reconstructed from the 48 fields by assembling a frame from each pair of fields that came from the same original film frame, without any motion between them (motion the interlaced video has between fields). In order to help on the identification of film source material for its frame reconstruction, a flag is usually inserted (but not always) within the MPEG-2 data stream to indicate that the content is sourced from film and has that frame structure cadence.

If the flag is used, or if the playback device (DVD player, HDTV) detects the 24 fps film frame cadence automatically, it instructs the internal circuitry (when suited with that) to perform a 2-3 pull-down processing to repeat some of the 48 fields to construct a 60 fields video sequence ‘in real time’, so a video display device can synchronize and display it properly at 60i.

Content originating from 60i video cameras is stored as is in the DVD and does not need of this playback technique because all the 60 fields are already within the signal. Additionally, a deinterlacing technique is used to convert the 60 interlaced fields x second video to 60 frames x second for the progressive outputs of the player (and the display device to show it as a progressive image).

The above also applies to 1080i HD resolution images sourced from 24 fps film, by applying the same technique, the film sourced HD image can be converted to 60 fields x second for 1080i sets, or 60 frames x second for progressive displays.

SDTV format of 480 interlaced visible lines of 704 total pixels each (in 16:9 or 4:3 aspect ratio), or of 640 total pixels each (in 4:3 aspect ratio). 480i is per frame (240 lines x two fields) at 30 fps (frames per second). 480i/30fps is similar to interlaced DVD quality. Comparatively, NTSC color television is also 480i visible lines but is analog in a 4:3 aspect ratio with 450 pixels edge to edge (also measured as 340 TVL lines of horizontal resolution per picture height).

EDTV format of 480 progressive visible lines of 704 total pixels each (in 16:9 or 4:3 aspect ratio), or of 640 total pixels each (in 4:3 aspect ratio). 480p is per frame at 24, 30, or 60fps. The 480p/60fps format is similar but in theory it should be better than progressive DVD quality, because the DVD progressive is the result of re-interleaving/line-doubling 480i/30fps stored DVD images, not 480p/60fps as EDTV, which should have better temporal resolution suitable for fast action content (like 720p is). This format was originally a SD format, in late 2000, the CEA promoted it to an EDTV level created for 480p.

Copy-protection protocol used by the IEEE1394 digital connection. It is also known as Digital Transmission Content Protection (DTCP). The name originates from the group of five companies that developed the standard.

HDTV format of 720 progressive visible lines of 1280 total pixels each in 16:9 aspect ratio. 720p is per frame at 24, 30, or 60 fps. ABC and ESPN are broadcasting in 720p/60fps. 720p is considered a better format for fast action images like sports due to higher temporal resolution than the other commonly used HDTV format (interlaced 1080i).

The higher temporal resolution of 720p allows the format to complete an image frame in 1/60 of a second while 1080i is only drawing 540 lines with half of the information of the frame of the format. On the next 1/60 of a second the 720p could record complete detail of a different fast moving image, while the 1080i would be registering picture information of only the second set of 540 lines containing only half of an image that could also have moved fast enough to produce interlace artifacts when putting the two fields together.

In late 2000, when the CEA created the additional EDTV level with the DTV formats, there were a number of 4:3 TV sets that manufacturers labeled HDTVs but only showed 810i lines of a 16:9 1080i image (25% less in the vertical resolution), using a letterbox approach to convey the rectangular widescreen geometry of the HD image within the 4:3 frame of the TV.

The remaining 270i lines (1080i minus 810i) of the TV set were wasted on scanning black information for the top/bottom bars, instead of using the lines for the benefit of the image. The concept is similar to what a DVD player does when a regular 4:3 TV displays a 16:9 image as letterbox (throwing away 1 line for every 3 kept to maintain geometry).

The new EDTV category was placed by the CEA between the original SDTV and HDTV standards, but instead of putting those 4:3 810i sets on that EDTV category the CEA did the following:

a) The 480p sets were promoted from SDTV to the EDTV level, and

b) The 810i (non-HDTV) 4:3 DTV sets were promoted to the group of fully capable HDTV sets (720p or 1080i). With time, manufacturers of 4:3 DTV sets gradually designed those to adjust their scanning raster so they could show all the 1080i lines of incoming signal closer together, all within the displayed 16:9 image; in those TVs the black bars are dead space, the TV is not using vertical resolution lines for the black bars (as opposed to the 810i style). It is recommended that consumers verify how a 4:3 DTV handles 16:9 images before making a purchase.

A-VSB is a DTV broadcast system for mobile purposes proposed to the ATSC in December 2005. During 2006 Sinclair Broadcast Group, Samsung Electronics, and transmitter manufacturer Rohde & Schwarz, joined efforts to successfully test DTV mobile reception at highway speeds.

At CES 2007, A-VSB was demoed, and expected to be included in the Advanced Television Systems Committee (ATSC) digital-TV standard by 1H07, and is backward compatible with 8-VSB the current DTV terrestrial system.

A-VSB, was previously simulated at NAB in April 2006, using forward-error-correction (FEC) “turbo-coding” for difficult signal environments, which used about one fifth of the transmitted bits for the actual video, the rest was to provide robustness so the signal is tuned well by the receiving device.

1.5 megabits per second (Mbps) of transmitted signal would have only 375 kbps of actual video. That number of bits is considered sufficient for small devices such as cellphones and PDAs.

The use of Single Frequency Network (SFN) within A-VSB can improve broadcast quality with higher uniform signal strength throughout a service area, even in locations that normally would have their signals interfered with by obstacles such as hills or buildings.

A broadcaster adds a specified Supplementary Reference Sequence (SRS) to the transmitted signal and A-VSB receivers can use the SRS in order to remain “locked in” to the transmission. This helps maintain reception of the main signal and extra ‘turbo’ signal(s) even when interference would normally disrupt a signal, like when the signal is reflected from moving objects near the receiver. A-VSB also enables the receiver to stay ‘locked on’ to the signal when the receiver itself is moving, such as when someone is walking with their portable TV.

Please consult the “DTV Standards” section of the HDTV Technology Review Report for 2007 for more information.

Electronic device that converts analog signals to digital. A D/A is also a similar device that performs the reverse function.

Equipment that performs filtering of power-line noise/interferences on AC (alternate current), and protects the connected audio/video components from voltage surges and spikes. Some line conditioners are designed with separate sections to connect digital or analog equipment in two groups; the design claims that such separation blocks the feedback of digital equipment from interfering with analog equipment.

Visible lines of the horizontal scanning (on NTSC is 480i of 525i, on HDTV is 1080i of 1125i). Blanking and vertical sync signals are within the non-visible lines.

Loudspeaker constructed to reproduce only low frequencies, with a power amplifier that is usually built within the speaker cabinet. Some subwoofers are ‘passive’, which means that the subwoofer requires a separate amplifier to drive the loudspeaker.

Connectivity standard for professional use established by the "Audio Engineering Society" and the "European Broadcasting Union" for digital audio transmission between equipment components. AES/EBU is carried on a balanced line terminated with three-pin XLR connectors. Sony/Philips’ S/P DIF is the consumer adaptation of this standard.

(also called as flicker) Effect of a CRT electron gun drawing the scanning lines too slow, which gives time for the phosphors to fade.

(also known as Interlace: i) Technique that displays a full frame of a picture by showing two different fields containing only half of the video information (such as 480i, 1080i).

(same as analogue) Continuous movement that takes time to change from one position to another. Standard analog audio and video signals have an infinite number of levels between their highest and lowest value, as opposed to digital that represent changes as only two steps (‘on’ or ‘off’, or binary’s ‘one’ or ‘zero’). Analog signals are stored magnetically, optical (films), and frequency modulated (Laserdiscs and VHS-HiFi).

(also specified as Widescreen video ‘enhanced for 16:9 televisions’) Technique that improves the vertical resolution of widescreen video (number of horizontal lines in the vertical direction). The technique horizontally squeezes a wider 1.78:1 aspect ratio (16:9) image to a 1.33:1 (4:3) image, making objects look thin and tall, so when the image is unsqueezed by the display, the original widescreen geometry of the image is restored without reducing the vertical resolution lines.

The result is a gain of 33% in vertical resolution compared to letterboxing with black bars (letterboxing takes away actual image content lines to show as black). In other words, a 16:9 image of 480i scanning lines would be shown with all its 480 lines, not as 360 of the letterboxed version (which discards 120 lines of image content to create top/bottom black bars so a regular 4:3 TV can show the image as widescreen).

Method of measuring brightness by which the display device is divided into nine rectangles and light is measured from the center of each rectangle, then averaged among the nine and expressed as lux (lumen/square meter), which is then multiplied by the number of square meters of the image at the plane of meter reading. The result is the light output specification expressed in lumens.

The ratio between the width and height of the video image. Standard NTSC television has a 4:3 (1.33:1) aspect ratio, which is similar to the Academy standard for films before the 1950’s, almost a square box shape. Widescreen screens are rectangular with a 16:9 aspect ratio (1.78:1); some widescreen display panels are only 15:9.

Widescreen sets are offered to the consumer in several flavors: front projection, rear projection, direct-view TVs, LCD TVs, and Plasma TVs. Some film aspect ratios are 1.85:1, anamorphic scope 2.35:1 or 2.40:1, and 65mm (70mm) from 2.05:1 to 2.21:1. Images from those wider aspect ratios are fitted within the 16:9 (1.78:1) HDTV image as a wider rectangle with top/bottom black bars (that use some vertical resolution lines of the 1080i or 480p DVD).

Advanced Television Systems Committee, the federal committee that selected the new DTV standard, which the US adopted on December 24, 1996 except for the full application of the 18 video formats described on the ATSC table III.

Automatic alignment of red, blue and green color images.

Range of frequencies that equipment for radio, TV, audio, and video operate and let pass-thru. The wider the bandwidth, the better the audio or video quality is. The higher the bandwidth, the better the performance of the equipment is. In a digital circuit, bandwidth is measured as bits per second.

Prime signal that is not modulated onto a carrier signal, but rather has its own path (composite, component, etc).

Devices and ports that can let pass signals in both directions (such as RS-232, IEEE1394).

(also known as brightness) Level of light produced on a video screen when it emits no light at all (screen black), the color NTSC system places the absolute black level at +7.5 IRE (unit of video defined by the Institute of Radio Engineers), a level that is higher than when the television was black and white, which set the absolute black level as 0 volts DC. The level was raised because B&W transmitters at that time could not handle a color signal with black level at zero volts.

Effect that occurs on CRT images when the light hitting the screen is too high overdriving the phosphors (in CRTs) in a way that edges of images appear to exceed their boundaries, because brightness or contrast might be too high, dispersing the light to adjacent areas.

Professional type of connector with a cylindrical shape with pins that lock into place.

(also known as black level) Intensity of light produced on a video screen, regardless of color.

Term given to the permanent damage on a video display caused when a fixed image has been shown for too long. CRT and PDP plasma panels are prone to burn-in; LCD and DLP chip-based displays are not. To reduce the risk of burn-in, some display devices shift the entire image just a few pixels at intervals, in a way that is not noticed by the viewer.

Usually manufacturers deliver displays with the contrast setting to its highest to increase the appeal of TV sets that stand out on fluorescent lighted showrooms. However, when you own the set it is always recommended keeping the contrast levels as low as possible until the display is properly calibrated, and to use stretching modes in 16:9 displays when viewing 4:3 images (to avoid long viewing with dark pillar bars).

Format that uses a ceiling (height) surround channel/speaker decoded from the center front and center back channels, using an algorithm similar to what Dolby Pro Logic uses when extracting and steering to the center front the signal decoded from L and R fronts. One war movie already explored that format.

In the late seventies a similar technology was developed by ADS, the Model 10 Acoustic Dimension Synthesizer. It was a comprehensive digital time-delay processor (and expensive at that time, almost $1000), the unit decoded a ceiling and center back surround channels/speakers in addition to the side/rear surrounds. After almost 25 years, the ceiling and back surround approach 'reinvents' itself.

This is the channel that primarily carries the dialogue from a movie soundtrack, but also contains a substantial portion of other non-dialogue sounds. The center channel also helps maintain the front sound imaging for off-center viewers. Center channel speakers are magnetically shielded.

The use of TV's small speakers (and small TV amps) as alternative for a missing center channel is not recommended as a permanent home-theater setup. The dialog and much of the sound of a movie comes from the center channel, some have estimated it in the order of 60% of the movie soundtrack.

When using the TV's small amp/speakers in a home theater their loudness capacity would be exceeded much earlier than the external L/R speakers/amp (assuming that is larger than the TV audio, as typically is). The effect could be worst if the system does not have a subwoofer to redirect low frequencies from a small center and surrounds. The distortion on the center channel would affect the clarity of the dialog over loud passages.

Additionally, sounds that are panning side-to-side would have different timbre while switching among speakers (from left to center to right) accompanying the video movement in that direction. Voices of people walking side-to-side will change their tone as they enter the TV's center speaker and as they depart from it, reason by which it is recommended for the center speaker to be of similar type and timbre than the L/R, and be driven by similar amplification as well.

Having this input in the DTV allows for the use of the internal speakers to reproduce the sound of the center channel in the home theater set-up. If the TV center channel input is line-level (RCA type), it can receive the center channel signal already decoded by an external surround processor, and use the TV set’s internal amplifier to drive the internal speakers of the TV.

If the center-channel input of the TV is speaker-level, it can receive a speaker cable carrying an amplified center channel signal from an A/V Receiver or separate amplifier, bypassing the TV’s internal amp. This may be useful if your audio/video system has insufficient space to place a center channel speaker, or you might want to start your surround system at a reduced cost. However, as mentioned in the Center Channel description, this approach should not be permanent.

Sometimes called ‘Hue’, is the term used to characterize color information, such as hue and saturation (not black, gray and white). Interference of chroma can be seen as rainbow images and color transition dots, caused by the interaction between the chrominance and luminance components of a composite video signal.

Multi-channel surround effect produced from two channel sources by using ambient information stored in a stereo recording, a stereo recording encoded for surround, and recordings specifically encoded in Circle Surround. The surround sound information sent to the surround speakers is stereo, as opposed to the monaural approach of Dolby Pro Logic. Circle Surround creates a believable front soundstage, apportioning the stereo signal more comfortably across the three front channels; this makes the system appealing for music listening.

Artificial outlines surrounding the edges of colored objects on the video image.

The correct color temperature of a video display should be 6500 degrees Kelvin, and expresses the color quality of a light source. The light source is bluer when the Kelvin measurement is high and reddish when it is low.

This filter separates the luminance and chrominance from the composite video signal, improving, resolution, picture quality, and reducing objectionable color patterns. Low-to-mid-line sets utilize a glass comb filter. Higher-end sets utilize a CCD or digital comb filter, which greatly enhances resolution. The highest quality comb filters are 3D-Y/C digital comb filters, and may be motion-adaptive.

Analog component video connections used typically for DVD players/recorders, HD-STB/PVRs, audio/video receivers, video switchers, D-VHS VCRs, and HDTVs are:

a) 3-wire 75 ohm coax analog YPbPr (YCbCr is actually 'digital' component video, and the nomenclature has been incorrectly used abroad for analog connections in consumer equipment), and

b) 5-wire RGB BNC or VGA 15 pin D-sub, with the horizontal and vertical sync signals separated from the other 3 signals. Component video connections do not carry audio, for which separate audio connectors are required, such as digital coaxial and optical (Toslink). Component video offers higher quality performance than composite and even S-video, it bypasses the composite en/decoding process, and color carrier frequency.

NTSC standard video connection (typically a yellowed jack/plug) for the passage of an interlaced video signal that has luminance (black and white information), chrominance (color), sync (horizontal and vertical), blanking, and color burst signals, all in one wire. The standard has been used also in VHS and laserdisc equipment. Regardless of the type of connection (component, composite, S-video) the use of gold plated jacks/plugs is known to offer better connectivity between them.

Range between the maximum and minimum values of brightness; contrast ratio (CR) is a measurement obtained from the division of both. The specification came from the same panel of experts that established the ANSI lumens as the measurement of brightness in 1992 (under the American National Standards Association). A ‘perceived’ CR measured from an image as viewed would differ from the CR measured at the lens of the projection device (FPTV), and differ from the CR measured at the screen point.

Alignment of the red, green, and blue CRT guns on a projected display device (RPTV or FPTV). Using the convergence controls of the TV, the three colors should overlap and display a white line on the crosshatch test pattern over the entire surface of the image. Display devices using fixed pixel arrays (such as DLP DMD chips) do not require convergence adjustments.

Vacuum tube containing an electron gun that drives an electron beam that rapidly hit a phosphor-coated screen and produce video images.

Name associated with the VGA connection with 15 pins for RGBHV signals.

Digital to analog converter (the inverse conversion is also mentioned as A/D).

Satellite system that distributes signals from the satellite to the individual receivers, such as DirecTV, Dish Network, and Voom.

Directional Correctional De-interlacing. Faroudja’s proprietary name for their de-interlacing chip currently used in many products.

(One-tenth of a Bel, named after Alexander Graham Bell) Logarithmic ratio used to measure power, sound pressure level, or voltage. A 3dB loss/increase is considered an attenuation/augmentation of half/double of its original value; zero dB is the threshold of hearing; 120dB is the threshold of pain.

Technique used in THX processors for rear speakers to create an ambient DSP sound field similar in spaciousness and depth as a commercial theater.

Fidelity of the reproduction of a video picture, affected by resolution.

(or re-interleaving) Technique that involves assembling pairs of interlaced fields into one progressive frame (1/60 of a second long), and showing it twice, over the same amount of time as two fields. The need for 60 flashes on the screen each second stems from a biological property called the Flicker Fusion Frequency, whereby the human brain needs to see a minimum number of single image flashes in a second to see motion without seeing flicker. See progressive scan below.

Audio jacks that can be either coaxial (RCA jack) or optical (Toslink) and allow for the passage of multi-channel digital audio signals over a single connection. There are other digital audio connections for multi-channel audio such as IEEE1394 (FireWire) used in some proprietary links between DVD players/Receivers/Processors, or the audio portion of HDMI. Digital connections are prone to less noise and interference than analog audio connections plus it keeps the signal in the digital domain.

DLP stands for Digital Light Processing. These projectors and rear projection televisions provide premium quality images with excellent black levels without the use of a CRT (Cathode Ray Tube). These projectors use a Digital Micro-mirror Device (DMD) to create images that are enlarged to fill the screen. The DMD chip has upwards of 1.3 million tiny mirrors to resolve 720x1280 HD resolution images.

In January 2004, the xHD3 DMD chip was introduced by Texas Instruments (TI, the manufacturer of DLP DMDs) that claimed having resolution enough to resolve 1080x1920 HD images, although using a 1080x960 DMD chip (half of the mirrors) and using a technique named wobulation. In 2005, TI announced the release on a true 1080x1920 DMD chip for front projectors, and new projectors using that technology were introduced at CES 2006. Since DLP is a reflective technology, DLP will typically have higher ANSI lumens and Contrast Ratios than LCD. A color wheel is employed to help create a full palette of colors on one-chip projection implementations, which can produce a "rainbow" viewing effect for some people; three-chip implementation does not need a color wheel to show all the range of colors.

Samsung’s proprietary name for their video enhancement technology "Digital Natural Image" enhancement.

Multi-channel perceptual encoding scheme. Initially, Dolby’s new surround system was called AC-3 (for audio coder 3). It was introduced in movie theaters in June 1992 as Dolby Stereo Digital (or Dolby SR). Dolby Surround is a single-band-limited surround channel with a range of 100 Hz to 7,000 Hz. Dolby Digital, on the other hand, offers a full dynamic range on five discrete main channels L, C, R, Ls, and Rs (20 Hz - 20,000 Hz), plus a separate .1 channel for Low Frequency Effects (LFE) intended to be reproduced by a subwoofer. The surround channels are in stereo (as opposed to mono with Dolby Pro Logic).

This format has been adopted as the audio standard for DTV signals. Perceptual encoding seeks to eliminate the data humans cannot hear, while maintaining all the information humans can hear, and was designed to encode multi-channel digital audio. It divides the audio spectrum of each channel into narrow frequency bands that correlate closely to the frequency selectivity of human hearing allowing coding noise to be very sharply filtered taking advantage of the psycho-acoustic phenomenon known as auditory masking. Coding noise stays close in frequency to the audio signal being coded. This effectively masks the noise.

AC-3 uses a "shared bit-pool" arrangement plus human auditory masking to make use of transmitted data as efficiently as possible, and allows multi-channel surround sound to be encoded at a lower bit rate than required by just one channel on a CD. Dolby Digital can process a 20-bit dynamic range digital audio signal over a frequency range of 20 Hz to 20,000 Hz +/- 0.5dB (LFE bass channel: 20 - 120 Hz +/- 0.5dB) with sampling rates of 32, 44.1 and 48 kHz with a typical data rate of 384 kbps (versus 1,411 kbps for DTS) with a compression rate of 12:1.

The AC-3 algorithm was designed by Dolby to faithfully reproduce film and music based programs with interference-free discrete channels, not folded or matrixed like Pro Logic; whatever the director wanted to be hear from a specific area, it is the only thing that will be heard from that area. Dolby Digital is ported out of a DVD player of HD-STB via its digital coaxial or optical output and fed directly into the digital coax or optical jack of a Dolby Digital decoder/processor or receiver (with built-in DD decoder).

A decoder/processor has six separate analog audio outputs, one for each discrete channel of the 5.1 Dolby Digital, five to be amplified by a separate power amp, .1 LFE to be amplified by an active subwoofer. Dolby has enhanced the basic 5.1 format with EX (adding a matrixed back surround channel extracted from Ls/Rs as Pro Logic extracts the Center channel, and Dolby Digital Plus, a new format to facilitate broadcasters with a more efficient compression method for the DD audio in DTV transmission (more on both formats below).

Dolby Digital Plus is a powerful, flexible codec based upon Core Dolby Digital technologies. For broadcasters, it provides higher efficiency coding at lower bit rates. For the new blue laser formats, it provides more channels, extended bit rates and higher quality.

The Dolby Digital Plus format was announced in April 2004 at NAB. Dolby Digital Plus enables broadcasters to transmit 5.1 at 50% (192 kbps) data rate of regular Dolby Digital (384 kbps). Compatibility with all existing Dolby Digital consumer decoders is ensured, as the Dolby Digital Plus signal will be upconverted to a standard 640 kbps Dolby Digital Plus output in the set top box (a set top box that performs the upconversion would be needed).

The format supports multiple languages in a single bit-stream, and was selected by the Advanced Television Systems Committee (ATSC) as the standard for future robust broadcast applications, and as an option for multichannel audio delivered by the Digital Video Broadcasting (DVB) Project for satellite and cable TV.

Dolby Digital Plus was also announced as capable of a higher-bit rate enhancement to Dolby's existing AC-3 (Dolby Digital) lossy audio compression format. Dolby Digital Plus format supports new levels of quality data rates as high as 6 Mbps on 7.1 channels, with a bit-rate performance of at least 3 Mbps on HD DVD and up to 4.7 Mbps on Blu-ray disc.

According to Silicon Image, although the HDMI transport is able to handle 18Mbps, Dolby Digital Plus has no ability to carry uncompressed audio nor can it be operated in a lossless way. Check the Multi-channel Audio for HD section of the H/DTV Technology Review report for applicability and connectivity details.

Dolby worked closely with Silicon Image to ensure transmission of Dolby Digital Plus signals on HDMI v. 1.3, earlier versions of HDMI are not capable of transmitting this format. Those protocols and specifications were finalized by mid-2006.

Dolby Digital Plus is a mandatory audio format in HD DVD players and an optional feature in Blu-Ray players.

Format of 6.1 multi-channel playback that provides a third surround channel (back) on Dolby Digital movie soundtracks encoded onto the left and right surround channels of 5.1 soundtracks. The format can be decoded by suited A/V receivers and Dolby decoders for playback over surround speakers located behind the seating area, while the left and right surround channels are reproduced by surround speakers to the sides.

To maintain compatibility, no information is lost when the film is played in conventional 5.1. The benefits of Dolby Digital Surround EX include more realistic flyover and fly-around effects, a more stable image for atmospheres and music, and a more consistent surround effect. No additional effect tracks are needed; the mixer directs the available sounds to the appropriate channels for greater directional precision.

Because the extra surround information is carried on the left and right surround channels, Dolby Digital Surround EX encoded soundtracks are still regarded as 5.1 soundtracks, although with respect to home playback, the terms 5.1, 6.1, and 7.1 mean that there are five, six, or seven main speakers, plus a subwoofer that still reproduces the LFE channel recorded on 5.1 soundtracks, plus any bass the main speakers cannot handle.

A 5.1-channel soundtrack can also be played on a 6.1- or a 7.1-speaker system, the two surround signals on the 5.1 soundtrack are spread across the three or four surround speakers by a Dolby Digital EX decoder, a THX Surround EX decoder, or other proprietary methods provided in home theater equipment by various manufacturers.

Matrixed surround system with four channels of information (Left, Center, Right, and Surround) that are folded into two channels and encoded onto the L/R channels. The Pro Logic processor, in turn, extracts those four channels from the two encoded channels, and steers or directs them to the appropriate speakers, e.g. dialogue to the center channel and mono effects to the rear.

Under this scheme, the rear surround channel mono signal is divided over two speakers, which gives it more coverage. The rear channel information is derived by the simple formula of L-R with added reverb to give it a more natural like sound. The Pro Logic format concept helped originate the newer Dolby Pro Logic II, and IIx.

Format that creates a 5.1 surround sound field from a two-channel stereo program material, whether or not it has been specifically Dolby Surround encoded. Encoded material, such as movie soundtracks, sounds more like Dolby Digital 5.1, while unencoded stereo material, such as music CDs, sounds like a wider effect and more involving sound field. Pro Logic II provides two full-range surround channels, as opposed to Pro Logic’s single, limited-bandwidth surround channel.

Format that works with 5.1 audio as well as two-channel material, producing up to 7.1 channels, by decoding center back and side surround channels from the left/right surround channels of Pro Logic II and 5.1 audio. Pro Logic IIx includes center channel width control and panorama mode, as well as music, movie and games modes. Dolby is positioning this format as an expansion of 5.1 audio with the option to extend it to 7.1 surround.

Introduced in September 2005, Dolby TrueHD can support up to 14 discrete of lossless 24-bit/96 kHz audio channels at bit rates as high as 18Mbps. HD DVD and Blu-ray disc standards currently limit their maximum number of audio channels to eight. Check the Multi-channel Audio for HD section of the H/DTV Technology Review report for applicability and connectivity details.

Dolby TrueHD

At CES 2007, Dolby announced a new feature called Dolby Volume, developed to level out sound differences in TV programming without the typical "pumping" and artifacts introduced by other technologies.

As said by Dolby, "some programmers use compression techniques that allow them to boost the volume of their material without exceeding the peak limits set by Government. Some operators of TV channels also make different esthetic decisions about volume levels or fail to operate equipment properly".

Dolby modeled how the human ear works; responding to the energy of sound waves, the pitch, and the tone quality of sounds, and applied formulas to reduce the volume differences between programs and commercials without losing the needed sounds.

Scheme created for the purpose of copy protection of digital video transmitted over the 1394 connection. DTCP is also known as 5c for the five companies that participated on the standard (Sony, Toshiba, Intel, Hitachi, and Matsushita). The format allows for copy freely, once, and never, as options of protection.

DTS originated as a digital 5.1 surround scheme developed for the movies by MCA/Universal and Steven Spielberg. DTS was first employed in Spielberg's Jurassic Park in the summer of 1993. While it has not been around as along as Dolby, hundreds of films have been released with DTS encoded surround soundtracks. DTS Coherent Acoustics Coding (CAC) maps discrete 6-channel, 20-bit encoded data onto the 16-bit PCM digital audio stream, which is found on either a laserdisc or compact disc.

DTS' CAC signal is passed via the digital output (either coaxial or optical) present on many laserdisc, CD, and DVD players. While Dolby Digital uses perceptual coding to reduce the bit rate, DTS uses compression technology and the CAC algorithm with a higher bit rate than DD. The compression ratio is 3.75:1 of a 20-bit PCM digital audio stream with eight times over-sampling rate. It has a typical data rate of 1,411 kb/s (as opposed to 384 kbps of Dolby Digital). It performs transparently by coding 20-bit data at a bit-rate lower than 16-bit linear PCM.

The Coherent Acoustic Coding algorithm is a scaleable digital coding methodology, which operates on a multirate filterbank. It has been designed to filter the audio signal into frequency bands, which match the critical perceptual bands of the human ear. Within each frequency band, the signals are re-quantified at a variable resolution. This is determined by the available bit-rate and an analysis of the long/short periodicity of the audio signal in each frequency band.

According to DTS, this allows an efficient sharing of the limited number of quantization bits without any transient pre-echo distortion. Furthermore, by coding the spectral analysis to extend and include all channels, the re-quantization routines are fed from a common bit-pool. DTS feels that this optimizes the coding performance and audio quality of each individual channel in a multi-channel format delivering a full-bandwidth for each.

Essentially, this allows six channels of transparent quality 24-bit recorded material at 48 kHz with less digital compression. While Dolby Digital uses a different approach of providing multi-channel sound with low bit-rates, the results might seem similar to the untrained ear.

Although the DTV standard does not include DTS as an audio alternative (only Dolby Digital), DTS was selected as a mandatory format for HD-DVD and Blu-ray players (in addition to Dolby Digital).

DTS announced that their new DTS++ (as named originally) would be capable of higher bit rates. In October 2004, the DTS++ name was changed to DTS-HD. In December 2005, DTS announced their demonstration of a 24 Mbps extension of the same format under a new name, DTS-HD Master Audio, 100% lossless and bit-for-bit identical to the studio master.

DTS-HD is a 100% lossless format using a set of extensions to the coherent acoustics audio coding system, comprised of DTS Digital Surround, DTS-ES, and DTS 96/24, which allows the format to down-mix to 5.1 and two-channel, or deliver audio quality at bit rates extending from DTS Digital Surround to 7.1 DTS-HD channels, using a single stream up to 18Mbps.

The format was approved as optional for HD DVD and Blu-ray.

Check the Multi-channel Audio section of the 2006 H/DTV Technology Review report for applicability on Hi-def DVD formats and connectivity details.

The format delivers up to 7.1 channels of sound said to be "virtually indistinguishable from the original soundtrack" using high constant bit rates and 96k sampling frequency / 24-bit depth resolution. The format offers an alternative for high quality audio when disc space for Master Audio is not sufficient for that higher format.

As with Master Audio, the audio format also contains the DTS 1.5 Mbps core for backward compatibility with legacy DTS-enabled audio devices and deliver of up to 6.1 channels of sound.

The format was approved as an option for HD DVD and Blu-ray. HD DVD can handle up to a maximum of 3 Mbps, and by Blu-ray up to a maximum of 6 Mbps.

A) Blu-ray Secondary Audio
Multi-channel sound "Secondary Audio" is a scalable format using low-bit rate audio, an optional feature on Blu-ray Disc, designed for network streaming, broadcast and Internet applications. Data rates range from 24 kbps per channel, at sampling rates of 48 kHz for Blu-ray Disc, and 44.1 kHz and 48 kHz for HD DVD, with a resolution up to 24-bits.

B) HD DVD DTS Sub Audio
An optional format for HD DVD discs, considered of high quality using low bit rate audio; designed for network streaming, broadcast and Internet applications. It's a two-channel (2.0) scalable format, using from 64 to 192 kbps data rates, and sampling rates from 8 kHz to 96 kHz with 24-bits resolution.

(Disclaimer: DTS graph shown under permission)

The format is bit-for-bit identical to the studio master using high variable bit rates to provide up to 7.1 audio channels at 96k sampling frequency / 24-bit word resolution, as well as containing the DTS 1.5 Mbps core soundtrack within the bit stream to be backward compatible with legacy DTS-enabled audio devices, and deliver up to 6.1 channels of sound. The format can also handle 192 kHz / 24-bit word resolution.

DTS-HD is a 100% lossless format using a set of extensions to the coherent acoustics audio coding system, comprised of DTS Digital Surround, DTS-ES, and DTS 96/24, which allows the format to down-mix to 5.1 and two-channel, or deliver audio quality at bit rates extending from DTS Digital Surround to 7.1 DTS-HD channels, using a single stream up to 24.5 Mbps (18 Mbps for HD DVD).

When the format was created, DTS announced that the original DTS++ would be capable of higher bit rates. In October 2004, the DTS++ name was changed to DTS-HD. In December 2005, DTS announced their demonstration of a 24.5 Mbps extension of the format, DTS-HD Master Audio, 100% lossless and bit-for-bit identical to the studio master. Later, the HD audio format below the Master Audio level was called DTS-HD High Resolution Audio, capable of up to 6 Mbps resolution.

The format was approved as an option for HD DVD and Blu-ray. HD DVD can handle up to a maximum of 18 Mbps, and by Blu-ray up to a maximum of 24.5 Mbps.