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|HDTV Jargon - Terms and Glossary|
If you are looking for some answers when it comes to confusing 'jargon' associated with HDTV, you are not alone. We have collected some definitions that may help educate you when it comes to talking about High Definition television.
Here is a list of words and terms commonly used in talking about HDTV.
1080p is the shorthand name for a category of HDTV video modes. The number "1080" represents 1,080 lines of vertical resolution (1080 vertical scan lines),while the letter p stands for progressive scan (meaning the image is not interlaced). 1080p can be referred to as full HD or full high definition to differentiate it from other HDTV video modes. The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal resolution of 1920 pixels. This creates a frame resolution of 1920×1080, or 2,073,600 pixels in total. The frame rate in hertz can be either implied by the context or specified after the letter p (or i), such as 1080p30, meaning 30 Hz.
In addition to the meaning of 1080p as a display resolution, 1080p is also used to describe video equipment capabilities. Use of 1080p and the closely related 1080i labels in consumer products may refer to a range of capabilities. For example, video equipment that up scales to 1080p takes lower resolution material and re formats it for a higher resolution display. The image that results is different from the display of original 1080p source material on a native 1080p capable-display. Similarly, equipment capable of displaying both 720p and 1080i may in fact not have the capability to display 1080p or 1080i material at full resolution. It is common for this material to be downscaled to the native capability of the equipment. The term "native 1080p-capable" is sometimes used to refer to equipment capable of rendering 1080p fully.
1080i is the shorthand name for a category of video modes. The i stands for interlaced, the 1080 for a vertical resolution of 1080 lines, usually with a horizontal resolution of 1920 pixels and an aspect ratio of 16:9; that is high-definition television. If not implied by context, the field rate (not the frame rate) in hertz is given after the letter. The two field rates in common use are 50 and 60 Hz. Contrary to myth, 1080i is not superior to 720p; 1080i has more scanning lines but also suffers the disadvantages of interlaced scanning.
720p is the shorthand name for a category of video modes. The p stands for progressive scan, i.e. non-interlaced, the 720 for a vertical resolution of 720 lines, usually with a horizontal resolution of 1280 pixels and an aspect ratio of 16:9; that is high-definition television. 720p is directly compatible with newer flat screen technology such as plasma and LCD which are inherently progressive and must perform deinterlacing to display 1080i source material. 720p is used by ABC and ESPN because the smoother image is desirable for fast-action sports telecasts. Proponents of 720p further argue that at the average viewing distance, with the average size of consumer HDTV sets, the human eye would not actually be able to perceive the difference in resolution between 720p and 1080p. This is because the 720p image "saturates" the perceivable resolution of the eye at this distance - watching from much closer to the monitor, however, the viewer would be able to see the difference.
Dolby’s third generation Audio Coding algorithm, also known as "Dolby Digital®." It’s the multi-channel sound system specified as the standard for Digital HDTV. AC-3 delivers CD-quality digital audio and provides five full-bandwidth channels for front left, front right, center, surround left and surround right speakers, plus an LFE (low frequency effect) subwoofer, for a total of 5.1 channels.
Analog to digital conversion (or converter).
Addressable Resolution -
The highest resolution signal that a display device (TV or monitor) can accept.
Caution: Consumers should be aware however, that although a particular device (Digital-HDTV) is able to receive the resolution, it may not be capable of displaying it.
Analog TV -
Analog TV is the NTSC Standard for traditional television broadcasts. Analog signals vary continuously, representing fluctuations in color and brightness.
Unwanted visible effects in the picture created by disturbances in the transmission or image processing, such as 'edge crawl' or 'hanging dots' in analog pictures, or 'pixelization' in digital pictures.
Aspect Ratio -
Refers to the width of a picture relative to its height. If an NTSC picture is 4 feet wide, it will be 3 feet high; thus it has a 4:3 aspect ratio. HDTV has a 16:9 aspect ratio.
The range of frequencies used to transmit information such as picture and sound. For TV broadcasters, the FCC has allocated 6Mhz for each channel. For DTV, the maximum bit rate possible within the bandwidth is 19.4 Mbps, which is one HDTV channel. SDTV has a lower bit rate, therefore the bandwidth can accommodate more than one channel.
Bit Rate -
Measured as "bits per second," and used to express the rate at which data is transmitted or processed. The higher the bit rate, the more data that is processed and, typically, the higher the picture resolution.
A 6 Mhz (bandwidth) section of broadcasting spectrum allocated for one analog NTSC transmission
Component Video Connection -
Output of a video device (such as a DTV set-top box), or the input of a DTV receiver or monitor consisting of 3 primary color signals: red, green, and blue that together convey all necessary picture information. With current consumer video products, the 3 component signals have been translated into luminance (Y) and two color difference signals (PB, PR), each on a separate wire.
Composite Video -
The analog, encoded video signal (such as NTSC) that includes vertical and horizontal synchronizing information. Since both brightness and color signals are encoded together, only a single connection wire is needed (i.e. RCA cables).
Electronically reduces the number of bits needed to store or transmit data within a specified time or space. Several types of compression methods are used buy the industry, but the method adopted for DTV is called "MPEG2." Ten or more full-range channels of programming and data can be compressed into the same space required by a single analog channel.
The conversion of digital to analog signals, also referred to as DAC (D/A converter). For conventional television technology to display digitally transmitted TV data, the data must be decoded first and then converted back to an analog signal.
DTCP - Digital Transmission Content Protection
A Digital rights management technology. The DTCP standard was issues by the DTLA (Digital Transmission Licensing Administrator) to protect multimedia distribution in the Digital Home. You should make sure that the HDTV set you are buying will support DTCP connections. Older HDTV sets may not have this.
Digital Television (DTV) -
Refers to all formats of digital television, including high definition television (HDTV), and standard definition television (SDTV). Also referred to as ATV (Advanced TV).
Digital Theater Systems sound. Discrete 5.1 channel surround system similar but not the same as Dolby Digital®. Dolby Digital is the DTV standard, but DTS competes with it on DVD and in the movie theaters.
Describes the format conversion from a higher resolution input signal number to a lower display number, such as 1080i input to 480i display.
DVI (Digital Video Interface) -
The digital visual interface or digital video interface (DVI) is a video connector designed to maximize the visual quality of digital display devices such as flat panel LCD computer displays and digital projectors. It was developed by an industry consortium, the Digital Display Working Group (DDWG).
EPG (Electronic Program Guide)-
On-screen display of channels and program data.
The number of times per second that a signal fluctuates. The international unit for frequency is the hertz (Hz). One thousand hertz equals 1 KHz (kilohertz). One million hertz equals 1 MHz (megahertz). One billion hertz equals 1 GHz (gigahertz). Television is broadcast in frequencies ranging from 54 MHz to 216 MHz (VHF) and 470 MHz to 806 MHz (UHF).
High Definition Television (HDTV)-
The popular definition of HDTV is approximately twice the vertical and horizontal picture resolution of today's NTSC TV, which essentially makes the picture twice as sharp. HDTV also has a screen ratio of 16:9 as compared with most of today's TV screens, which have a screen ratio of 4:3. HDTV offers reduced motion artifacts (i.e. ghosting, dot crawl), and offers 5.1 independent channels of CD-quality stereo surround sound, (also referred to as AC-3).
High-Definition Multimedia Interface (HDMI)-
An industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any compatible digital audio/video source, such as a set-top box, DVD player, and A/V receiver and a compatible digital audio and/or video monitor, such as a digital television (DTV). HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable.
High Definition Video (HDV) -
Video format which is intended to provide the facility to record high-definition (as opposed to standard definition) MPEG-2 video on standard DV media (DV or MiniDV cassette tape).
Since the frame size of HDV is much larger than the SD frame size, the data stream needs to be compressed before it is recorded to tape. This compression ensures that a 60 minute MiniDV tape can still hold 60 minutes of HDV footage. The frame size of HDV is either 1280x720 or 1440x1080 (compared to the standard 1920x1080 that is defined for 1080i HD). Despite this, HDV footage can be mixed with more tradional HD footage in post production.
IEEE 1394 -
High-speed digital video/audio and data interface technology that allows a true digital stream to be sent and copied. In computer usage also known as “Firewire”. Not a good solution for HDTV as currently the on screen guide and VOD menus cannot be transferred over this connection. Only digital connections will work with IEEE 1394, thus analog cable channels will not work over this connnection.
Interlaced Scanning -
Refers to the process of re-assembling a picture from a series of electrical (video) signals. The "standard" NTSC system uses 525 scanning lines to create a picture (frame). The frame/picture is made up of two fields: The first field has 262.5 odd lines (1,3,5...) and the second field has 262.5 even lines (2,4,6...). The odd lines are scanned (or painted on the screen) in 1/60th of a second and the even lines follow in the next 1/60th of a second. This presents an entire frame/picture of 525 lines in 1/30th of a second.
Describes the way a 16:9 aspect ratio image is displayed on a 4:3 screen, where black areas are visible above and below the image.
Line Doubling -
The method, through special circuitry, to modify an NTSC interlaced picture to create an effect similar to a progressively scanned picture. The first field of 262.5 odd-numbered lines is stored in digital memory and combined with the even-numbered lines. Then all 525 lines are scanned in 1/30th of a second. The result is improved detail enhancement from an NTSC source.
National Television Standards Committee responsible for developing Standards for "traditional" Analog TV, prior to Digital-HDTV.
PAL (Phase Alternation Line) -
The signal format used in video equipment in Europe and parts of Asia. PAL signals give you 25 frames per second, and so are incompatible with NTSC, the American video signal format.
Pixel Term used for "picture element;" the smallest element in a television picture. The total number of pixels limits the detail that can be seen on a television. A typical television set has less than half a million pixels. The pixel count for HDTV is nearly two million.
Progressive Scanning -
Typically used by VGA computer monitors, all the horizontal scan lines are 'painted' on the screen at one time. Adopted DTV formats include both interlaced and progressive broadcast and display methods. Progressive Scanning handles each frame of video much differently. Progressive scanning eliminates the need to draw two separate fields for each frame of video. Instead, Progressive Scanning draws every scan line, even and odd, for each frame. Progressive scan is usually 60 frames per second, or 60 full frames per second.
The density of lines and dots per line which make up a visual image. Usually, the higher the numbers, the sharper and more detailed the picture will be. In terms of DTV, maximum resolution refers to the number of horizontal scanning lines multiplied by the total number of pixels per line, called pixel density.
SECAM (Système Electronique Couleur Avec Mémoire) -
The signal format used in video equipment in France and the former Soviet Union. It is incompatible with PAL and NTSC formats.
Set-top Box STB)(also: Decoder, Receiver, Tuner) -
A unit similar to today's cable boxes that is capable of receiving and decoding DTV broadcasts. A DTV 'Certified' STB can receive all (18) ATSC DTV formats, (including HDTV) and provide a displayable picture.
Range of frequencies available for over-the-air transmission.
Standard Definition Television (SDTV)-
Refers to DIGITAL transmissions with 480-line resolution, either interlaced or progressive scanned formats. SDTV offers significant improvement over today's conventional NTSC picture resolution, similar to comparing DVD quality to VHS, primarily because the digital transmission eliminates snow and ghosts, common with the current NTSC analog format. However, SDTV does not come close to HDTV in both visual and audio quality.
S-Video (Separated video)-
An encoded video signal which separates the brightness from color data. S-video can greatly improve the picture when connecting TVs to any high quality video source such as digital cable and DVDs.
UHF (Ultra High Frequency)-
The range used by TV channels 14 through 69.
Describes the conversion of a lower apparent resolution to a higher number, such as "upconverting" 720p to 1080i. This is a misnomer, though, since to accomplish this, the horizontal scanning frequency is actually lowered from 45kHz to 33.75kHz. Resolution quality is not improved by this method.
VHF (Very High Frequency)-
The range used by TV channels 2 through 13.
Y, PB, PR -
This is a high quality component analog interface. Generally used where a digital TV signal source is employed. Preferred connection for High Definition TV signals; enables superior quality in transmitted picture. The video signal is separated into its component parts of brightness and color differentials.
Y, U, V -
Sometimes referred to as Y, Cr, Cb, where a video signal is separated into components of brightness and color, arguably to a degree more advanced than S-video.