Betacam
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Reproductor Sony Betacam-SP BVW-65
Comparación de tamaños de cinta Betacam y VHS
Betacam SP L (arriba), Betacam SP S (izquierda), VHS (derecha)
Betacam es una familia de formatos de vídeo profesional de media pulgada (1/2″) creada por Sony en 1982.
Todos los formatos usan el mismo tipo de cinta magnética, que es lo que define a Betacam, con idéntico tamaño, ancho de cinta y forma de enhebrado. Sus distintas variantes lo convierten un sistema altamente compatible y con una amplia evolución. Las cintas tienen dos tamaños distintos: S y L. Las cámaras Betacam sólo admiten el tamaño S, mientras que los magnetoscopios soportan S y L. Las cintas y los estuches tienen colores distintos dependiendo del formato específico del que se trate. Betacam incorpora una clave mecánica que permite al magnetoscopio identificar a qué sistema pertenece la cinta insertada en él.
Variantes de Betacam [editar]
Betacam / Betacam SP [editar]
El primer formato ‘Betacam’ fue lanzado en 1982. Es un sistema analógico de vídeo por componentes, que almacena la luminancia (Y) en una pista y la crominancia (Y-R, Y-B) en otra distinta. La separación de las señales proporciona una calidad suficiente para un entorno broadcast y 300 líneas verticales de resolución.
El Betacam original utiliza cintas magnéticas de óxido, que son exactamente las mismas que su versión doméstica, el Betamax, creado también por Sony en 1975. Las cintas vírgenes Betacam se pueden usar en magnetoscopios Betamax y viceversa. La diferencia entre ambos formatos consiste en que Betamax graba una señal de vídeo compuesto (al igual que otros formatos como VHS, U-Matic y el formato C de 1 pulgada, mientras que Betacam usa una señal por componentes y una mayor velocidad de paso de cinta, lo que proporciona mejor calidad de audio y vídeo. Una cinta L-750 permite 3 horas de grabación en Betamax y sólo 30 minutos de grabación en Betacam, pero con una calidad muy superior.
El Betacam SP fue creado en 1986, y mejoraba su resolución a 340 líneas verticales y añadía dos pistas de audio. Betacam SP (SP significa “Superior performance”, es decir, “rendimiento superior”) se convirtió en el estándar de vídeo para las cadenas de televisión y la producción de gama alta hasta la entrada de los formatos digitales a partir de mediados de los 90. Aunque los tamaños y duraciones de cinta son iguales, las cintas de Betacam SP usan metal evaporado en lugar de óxido, de menor calidad, por lo que no se puede utilizar el mismo soporte. En la práctica hay una variación en la duración de las cintas en PAL, puesto que las marcas comerciales indican la duración para NTSC. Por cada 5 minutos de cinta se añade uno adicional; así una cinta Betacam vendida como de 30 minutos en PAL durará 36 minutos.
Toda la gama Betacam está diseñada para ser compatible entre sí, pero sólo con versión anteriores y generalmente en lectura. Esto significa que un equipo Betacam SP podrá leer (sólo leer) cintas Betacam, pero no podrá grabar con ellas y Betacam no podrá leer Betacam SP. Según Sony ha ido incorporando formatos con el sistema Betacam ha ido manteniendo está compatibilidad. Por tanto existen magnetoscopios MPEG IMX que leen Betacam, Betacam SP, Betacam Digital, Betacam SX y MPEG IMX. Esta es una de las grandes ventajas que han permitido el éxito de la gama Betacam, puesto que no hace necesario repicar/convertir el archivo guardado en versiones antiguas.
Magnetoscopio VBVW-75P de Sony. Formato Betacam SP
Betacam y Betacam SP suele utilizar cintas de color negro o gris.
Las primeras videocámaras Betacam venían acompañadas de un magetoscopio reproductor. Los primeros modelos fueron la BVP-3, que usaba 3 tubos Saticon, y la BVP-1, con un único tubo Trinicon de 3 bandas. A pesar de venir acompañadas por un magnetoscopio (BVW-1), son equipos camcorder, es decir, cámaras con magnetoscopio incorporado. Las cintas sólo podían reproducirse en la cámara a través del visor en blanco y negro. Para visionar en color existía un magnetoscopio de estudio, el BVW-10, que sin embargo era sólo reproductor. En un principio Betacam estaba concebido sólo como formato de captación ENG. Para montar se usaban editoras A/B ROLL que reproducían Beta y grababan C-1″ o U-Matic. Además, la primera gama de equipos incluía un reproductor portátil (BVW-20) con monitor en color, lo que permitía comprobar la imagen in situ. Al contrario que el BVW-10, no llevaba incorporado un TBC (Time Base Corrector).
Con el éxito de Betacam como formato para informativos, la gama pronto incluyó el reproductor de estudio BVW-15 y el magnetoscopio grabador BVW-40. El BVW-15 añadía dynamic tracking, que permite una visualización óptima de la imagen con velocidad variable y congelados. El BVW-40 fue el primer equipo que permitió la grabación y edición en Betacam y, por tanto, por componentes. También se podía hacer una edición máquina a máquina sencilla por corte con los magnetos BVW-10/15 y BVW-40. Se añadieron además dos equipos para el trabajo de campo: el grabador BVW-25 y el reproductor portátil BVW-21.
Los primeros años hubo críticos que afirmaban que Betacam era inferior a los formatos C y B, los estándares del audiovisuales en los 70 y 80. Además existía una importante limitación en la duración de las cintas, que duraban sólo media hora. Sony respondió creando el Betacam SP que incorporaba no demasiadas novedades en cuanto al formato en sí, pero que añadía importantes variaciones en cuanto al magnetoscopio, con grandes mejoras en calidad, características, y con la novedad del tamaño L de cinta, que permitía grabar más de 90 minutos en un único soporte.
Las nuevas máquinas de estudio fueron los reproductores BVW-60 y BVW-65, con dynamic tracking, y los grabadores BVW-70 y BVW-75, este último con dynamic tracking incluido. El BVW-5, el magnetoscopio adosado al camcorder, permitía visionar en color usando un adaptador. existía un grabador ligero, el BVW-35, que incorporaba el puerto serial RS-422, que permitía utilizarlo con controladores de edición. A pesar de que los nuevos equipos de estudio podían usar cintas de tamaño L, el BVW-35 no las admitía por ser una versión más barata. Sony incorporó el BVW-22, un reproductor barato enfocado a labores de visionado y minutado y que no podía ser usado para edición.
Más tarde se incorporó a la gama de trabajo de campo el BVW-50, que grababa y reproducía cintas L y que se mantuvo durante una década, y casi sin variaciones, con el estándar más vendido.
Hasta la incorporación de la cámara BVW-400, el magnetoscopio iba adosado a la cámara (docking system), lo que permitía cambiarlo por otro. La BVW-400 fue el primer modelo con magnetoscopio integrado, lo que restaba flexibilidad, pero también muchísimo peso (algo esencial en trabajo ENG). De hecho, los modelos integrado son los que se han consolidado en el mercado.
Magnetoscopio TTV 3452-P de Sony. Formato Betacam digital
El último camcorder Betacam SP fue el BVW-600, cuyo frontal es muy similar al del modelo BVW-700, que es Betacam Digital. Al igual que los demás Betacam, no puede reproducir en color sin adaptador.
En los noventa Sony creó una línea inferior para vídeo industrial dentro de la gama (la calidad para televisión se conoce como calidad broadcast). A principios de década lanzó el reproductor PVW-2600 y el grabador PVW-2800, que carecían de las pistas 3 y 4 de audio AFM. A mediados de los 90 fue el turno de los baratos UVW, más sencillos, que traían un panel frontal limitado y carecían de jog y shuttle. Eran el reproductor UVW-1600 y el grabador UVW-1800.
Betacam Digital [editar]
Cinta Betacam Digital tamaño L
El Betacam Digital (conocido también como Digi Beta y DBC) fue lanzado en 1993. El sistema venía a suplantar a Betacam y Betacam SP, aunque en la práctica han convivido y siguen conviviendo por cuestiones prácticas y económicas (en 2004 todavía se seguía usando Beta SP en grandes cantidades en Televisión Española). A la vez Betacam Digital fue la primera apuesta económica de Sony en digital, frente al D1, ofreciendo alta calidad a un precio aceptable. Las cintas S llegan a los 40 minutos y las L hasta 124 minutos de duración.
Betacam Digital graba usando una señal de vídeo por componentes comprimida con el algoritmo DCT (el ratio de compresión es variable, normalmente alrededor de 2:1). Su profundidad de color es de 10 bit y su frecuencia de muestreo es 4:2:2 en PAL (720×576) y NTSC (720×486), con el resultado de un bitrate de 90 Mb/s. En cuanto a sonido proporciona 4 canales de audio PCM a 48 KHz y 20 bits. Incluye dos pistas longitudinales para control track y código de tiempo.
Betacam Digital es considerado tradicionalmente el mejor formato de vídeo digital de resolución estándar (SD). En general es usado como formato de cinta para másters y trabajos de calidad media-alta, especialmente postproducción y publicidad, aunque algunas empresas lo usan para cualquier cometido. Es más caro que otros como el DVCAM y el DVCPRO, pero proporciona mayor calidad. Panasonic tiene un formato algo parecido, el DVCPRO 50.
Otro factor que contribuyó al éxito del Beta Digital es la incorporación en los magnetoscopios de la conexión digital SDI, de tipo coaxial. Las empresas podían usar un formato digital sin necesidad de renovar todo el cableado coaxial previo.
Betacam Digital usa cintas de color azul.
| Características técnicas de Betacam Digital |
| Sistema |
Digital SD. Por componentes |
| Frecuencia de muestreo |
4:2:2 |
| Algoritmo |
DCT intraframe |
| Ratio de compresión |
2:1 |
| Bitrate |
90 Mb/s |
| Profundidad de color |
10 bits |
| Ancho de cinta |
1/2″ |
| Canales de audio |
4 canales PCM |
| Muestreo de audio |
48 KHz / 20 bits |
Betacam SX [editar]
Cinta Betacam SX tamaño S
Betacam SX es un formato digital creado en 1996, con la idea de ser una alternativa más barata al Betacam Digital, especialmente para trabajos ENG. Comprime la señal por componentes usando MPEG-2 4:2:2 Profile@ML (MPEG-2 4:2:2P@ML), con 4 canales de audio PCM a 48 KHz y 16 bits. Betacam SX es compatible con cintas de Betacam SP. El tamaño S guarda hasta 64 minutos y el tamaño L, hasta 194.
Al crear el formato, Sony ideó una serie de camcorders híbridos, que permitían grabar tanto en cinta como en disco duro, así como un repicado a alta velocidad. Así se ahorraba desgaste de los cabezales de vídeo y se aceleraba la captura de cara a la edición no lineal. También incorporó el good shot mark, que permitía incorporar marcas en la cinta. El equipo podía acceder rápidamente a estas marcas y reproducirla.
Betacam SX usa cinta de color amarillo.
| Características técnicas de Betacam SX |
| Sistema |
Digital SD. Por componentes |
| Frecuencia de muestreo |
4:2:2 |
| Algoritmo |
MPEG-2 4:2:2P@ML interframe |
| Ratio de compresión |
10:1 |
| Bitrate |
18 Mb/s |
| Profundidad de color |
8 bits |
| Ancho de cinta |
1/2″ / disco duro |
| Canales de audio |
4 canales PCM |
| Muestreo de audio |
48 KHz / 16 bits |
MPEG IMX es una variante del Betacam creado en 2001. Utiliza, al igual que Betacam SX, una compresión MPEG, pero con un bitrate superior. Comparte la norma CCIR 601, con hasta ocho canales de audio y una pista de código de tiempo. Carece de una pista analógica de control track como el Betacam Digital, pero puede usar la pista 7 de audio para este cometido.
Es un sistema de vídeo por componentes comprimido con el MPEG-2 4:2:2P@ML. Permite tres niveles de bitrate distintos: 30 Mb/s (compresión 6:1), 40 Mb/s (compresión 4:1) y 50 Mb/s (compresión 3,3:1).
Con los magnetoscopios IMX, Sony introdujo dos nuevas tecnologías: SDTI y e-VTR. SDTI permite que vídeo, audio, TC y control remoto viajen por un sólo cable coaxial. e-VTR hace que los mismo datos puedan ser trasmitidos por IP a través de una conexión ethernet. También incluye la función good shot mark de Beta SX. Las cintas de tamaño S graban hasta 60 minutos y las de tamaño L, hasta 184 minutos.
MPEG IMX usa cintas de color verde. El formato también forma parte de la gama XDCAM, y puede grabar en Professional Disc, una especificación de Blu-ray Disc para vídeo broadcast.
| Características técnicas de MPEG IMX |
| Sistema |
Digital SD. Por componentes |
| Frecuencia de muestreo |
4:2:2 |
| Algoritmo |
MPEG-2 4:2:2P@ML interframe |
| Ratio de compresión |
3,3:1 / 4:1 / 6:1 |
| Bitrate |
50 Mb/s / 40 Mb/s / 30Mb/s |
| Profundidad de color |
8 bits |
| Ancho de cinta |
1/2″ / Professional Disc |
| Canales de audio |
8-4 canales PCM |
| Muestreo de audio |
48 KHz / 16-24 bits |
HDCAM / HDCAM SR [editar]
HDCAM, creado en 1997, es una versión de Alta definición (HD) de la familia Betacam, y mantiene la misma cinta de 1/2 pulgada. Utiliza una frecuencia de muestreo 4:2:2 y 8 bits de profundidad de color en vídeo por componentes. Este formato, al tratarse de HD, permite grabar en resoluciones superiores, a 720 y 1080 líneas. Además, como está destinado al cine, además de a los habituales 25 y 30 frames por segundo con exploración entrelazada (25i, 30i), PAL y NTSC respectivamente, graba a una velocidad de 24 fps (24p), la misma que se usa en cine con soporte fotoquímico. Además puede realizar exploración progresiva, además de la exploración entrelazada tradicional de vídeo. Su bitrate de vídeo es 144 Mb/s. En cuanto a audio graba 4 canales de audio AES/EBU a 48 KHz y 20 bits.
HDCAM usa cinta negra con pestaña naranja.
| Características técnicas de HDCAM |
| Sistema |
Digital HD. Por componentes |
| Patrón de muestreo |
3:1:1 |
| Algoritmo |
DCT intraframe |
| Exploración |
Progresiva / Entrelazada |
| Bitrate |
144 Mb/s |
| Profundidad de color |
8 bits |
| Ancho de cinta |
1/2″ |
| Canales de audio |
4 canales PCM |
| Muestreo de audio |
48 KHz / 20 bits |
HDCAM SR es una variación del anterior creada en 2003. Utiliza una cinta con alta densidad de partículas que permite grabar una señal RGB con muestreo 4:4:4 a un bitrate de 440 Mb/s. Esto permite capturar una resolución máxima de 1920×1080 y hasta 12 canales de audio. HDCAM SR usa una compresión MPEG-4 Studio Profile de alta calidad que no utiliza grupos de imágenes (GOP), por lo que no da los típicos problemas de MPEG a la hora de editar y usa compresión intraframe en progresivo y compresión intracampo en entrelazado. Algunos magnetoscopios HDCAM SR tienen un segundo modo que alcanza los 880 Mb/s, lo que permite un único flujo de vídeo con menor compresión o dos flujos simultáneamente. El modo 440 Mb/s es SQ y el modo 880 Mb/s, HQ. HDCAM SR sigue permitiendo un 4:2:2 por componentes.
La duración de cintas es la misma que el formato Betacam Digital: 40 para la talla S y 124 para el tamaño L. En su versión de 24 fps alcanza los 50 y 155 minutos, respectivamente.
HDCAM SR usa cinta negra con pestaña azul.
Dentro de los formatos HDCAM y HDCAM SR, Sony cuenta con la gama CineAlta, con equipos especialmente diseñados para su uso en rodajes de cine.
| Características técnicas de HDCAM SR |
| Sistema |
Digital HD. RGB / Por componentes |
| Patrón de muestreo |
4:4:4 / 4:2:2 |
| Algoritmo |
MPEG-4SP intraframe / intracampo |
| Exploración |
Progresiva / Entrelazada |
| Bitrate |
440 Mb/s |
| Profundidad de color |
12 / 10 bits |
| Ancho de cinta |
1/2″ |
| Canales de audio |
12 canales PCM |
Pistas en Betacam [editar]
Esquema en trazas de la grabación de información en el formato Sony Betacam SP
El sistema Betacam tiene un modo de grabación de la información sobre la superficie de la cinta que es necesario comprender para entender el funcionamiento del formato y de muchos sistemas de edición de vídeo. Como la inmensa mayoría de los formatos, graba la información de vídeo en trazas helicoidales (oblicuas) y el resto de información en trazas longitudinales (horizontales). Este sistema viene heredado de los primeros formatos de vídeo como el B y el C. Una de las principales ventajas respecto a los sistemas que le precedieron fue su capacidad de grabar de manera independiente la información de la señal de luminancia Y (B/N)y la señal de crominancia C (B-Y, R-Y).
Betacam SP graba la información de vídeo en 4 trazas cada pasada. Las dos interiores contienen la información de luminancia (Y) y las dos exteriores, la crominancia (C). Asimismo, las exteriores llevan incluidas las pistas 3 y 4 de audio, que van en frecuencia modulada. Esto puede dar problemas y muchas veces estas dos pistas de audio sufren interferencias. En las mismas pistas verticales está la información relativa al VITC (Vertical Interval Time Code).
Las pistas longitudinales graban audio e información de track y código de tiempo. Las dos superiores graban audio 1 y 2, quedando la 1, generalmente usada para locuciones, en el interior, más protegida. Las inferiores graban TC en el exterior, y control track en el interior, para que vaya resguardada, ya que se trata de información sobre el giro del motor de lectura/grabación. Es usado en todo el mundo
High-definition television
From Wikipedia, the free encyclopedia
High-definition television (HDTV) is a digital television broadcasting system with higher resolution than traditional television systems (SDTV) . HDTV is digitally broadcast because digital television (DTV) requires less bandwidth if sufficient video compression is used.
[edit] History of high-definition television
- Further information: Analog high-definition television system
The term high definition used to describe a series of television systems from the 1930s and 1940s, starting with the British 405-line black-and-white system introduced in 1936, and including the American 525-line NTSC system established in 1941. However, these systems were only “high definition” when compared to earlier systems.
All such so-called high definition systems were based on the Thorn-EMI electrical system, as opposed to the Baird et al mechanical systems. The BBC approved the Thorn-EMI system for national use by the summer 1937.
A brief itemized history of early analog HD systems follows; these would be considered standard definition television systems today.
- 1936 : System-A, UK: 405 lines @ 50 hz, discontinued 1986
- 1938 : Several countries used a 441 line system, France in 1956 being the last to discontinue it
- 1939 : System-M, USA: 525 lines @ 60 hz
- 1952-1956: European adoption of 625 lines @ 50 hz with PAL and SECAM color coming in 1956
- 1956 : French (monochrome) 819 line @ 50 hz system launched, discontinued 1986
All used interlacing and a 4:3 aspect ratio.
The post–WWII French 819-line black-and-white system was high definition in the contemporary sense, but was discontinued in 1986, a year after the final British 405-line broadcast. Neither the 405 line nor the 819 line television system supported color transmission in any form.
Since the formal adoption of DVB’s widescreen HDTV transmission modes in the early 2000s the 525-line NTSC (and PAL-M) systems as well as the European 625-line PAL and SECAM systems are now regarded as (so called) standard definition television systems.
The modern HDTV-technology is developed by the swedish engineer Östen mäkitalo.
In Mexico, Guillermo González Camarena (1917–1965), invented an early color television transmission system. He received patents for color television systems in 1942 (U.S. Patent 2,296,019), 1960 and 1962. The 1942 patent (filed in Mexico on August 19, 1940) was for a synchronized color filter wheel adapter for monochrome television, similar to the field sequential color receiver demonstrated by Baird in England in July 1939[53] and by CBS in the United States in August 1940.
On August 31, 1946 González Camarena sent his first color transmission from his lab in the offices of The Mexican League of Radio Experiments at Lucerna St. #1, in Mexico City. The video signal was transmitted at a frequency of 115 MHz. and the audio in the 40 meter band. He made the first publicly announced color broadcast in Mexico, on February 8, 1963, of the program Paraíso Infantil on Mexico City’s XHGC-TV.
In 1958, the U.S.S.R. created Тransformator (Russian: Трансформатор, “Transformer”), the first high-resolution (definition) television system capable of producing an image composed of 1,125 lines of resolution for the purpose of television conferences among military commands; as it was a military product, it was not commercialized.[1]
[edit] Modern systems
In 1969, the Japanese state broadcaster NHK first developed consumer high-definition television with a 5:3 aspect ratio, a slightly wider screen format than the usual 4:3 standard.[2] However, the system was not launched publicly until late in the 1990s.
In 1981, the first HDTV demonstration in the United States was held. It had the same 5:3 aspect ratio as the Japanese system.[3] Upon visiting a demonstration of the Japanese MUSE HDTV system in Washington, US-President Ronald Reagan was most impressed and officially declared it “a matter of national interest” to introduce HDTV to the USA. Several systems were proposed as the new standard for the USA, including the Japanese MUSE system, but all were rejected by the FCC because of their higher bandwidth requirement.
A new standard had to be radically efficient, needing less bandwidth for HDTV than the existing NTSC standard for SDTV. It was commonly understood only a digital system could possibly bring desired results, however nothing such had yet been developed. Pattern-recognition research for cruise missile development at the NASA Jet Propulsion Laboratory provided the basis for developing the MPEG set of compression standards.
[edit] The rise of digital compression
As soon as the MPEG1 standard provided the foundation for digital TV, development of modern TV standards started worldwide. After finalization of MPEG2 in mid 1993, the DVB organisation within the International Telecommunication Union‘s radio telecommunications sector (ITU-R) developed the ETSI standard 300-327 by the end of December 1993.
It became known as DVB-T for digital terrestrial TV. DVB-S and DVB-C standards soon followed for terrestrial, satellite and cable transmission of SDTV and HDTV. In the USA the Grand Alliance proposed ATSC as the new standard for SDTV and HDTV. Both ATSC and DVB were based on the MPEG2 standard. The DVB-S2 standard is based on the newer and more efficient MPEG4 compression standards. Common for all DVB standards is the use of highly efficient modulation techniques for further reducing bandwidth, and foremost for reducing receiver-hardware and antenna requirement.
In 1983, the International Telecommunication Union‘s radio telecommunications sector (ITU-R) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. One of the thornier issues concerned a suitable frame/field refresh rate, with the world already strongly demarcated into two camps, 25/50Hz and 30/60Hz, related by reasons of picture stability to the frequency of their mains electrical supplies.
The WP considered many views and through the 1980s served to encourage development in a number of video digital processing areas, not least conversion between the two main frame/field rates using motion vectors, which led to further developments in other areas. While a comprehensive HDTV standard was not in the end established, agreement on the aspect ratio was achieved.
Initially the existing 5:3 aspect ratio had been the main candidate, but due to the influence of widescreen cinema, the aspect ratio 16:9 (1.78) eventually emerged as being a reasonable compromise between 5:3 (1.67) and the common 1.85 widescreen cinema format. An aspect ratio of 16:9 was duly agreed at the first meeting of the WP at the BBC‘s R & D establishment in Kingswood Warren.
The resulting ITU-R Recommendation ITU-R BT.709-2 (“Rec. 709“) includes the 16:9 aspect ratio, a specified colorimetry, and the scan modes 1080i (1,080 actively-interlaced lines of resolution) and 1080p (1,080 progressively-scanned lines).
It also includes the alternative 1440 x 1152 HDMAC scan format. (According to some reports, a mooted 720p format (720 progressively-scanned lines) was viewed by some at the ITU as an “enhanced” television format rather than a true HDTV format[4], and so was not included, although 1920×1080 and 1280x720p systems for a range of frame and field rates were defined by several US SMPTE standards.)
[edit] The demise of analog HD systems
However, even that limited standardization of HDTV did not lead to its adoption, principally for technical and economic reasons. Early HDTV commercial experiments such as NHK’s MUSE required over four times the bandwidth of a standard-definition (SDTV) broadcast, and despite efforts made to shrink the required bandwidth down to about 2 times that of SDTV, it was still only distributable by satellite. In addition, recording and reproducing a HDTV signal was a significant technical challenge in the early years of HDTV.
HDTV technology was introduced in the United States in the 1990s by the Digital HDTV Grand Alliance, a group of television companies and MIT.[5][6] On 6th April 1997, CBS went on the air with WCBS-HD from the top of the Empire State Building, New York, doing demos and evaluations.[7] The first HDTV sets went on sale in the United States in 1998.
In Europe, analog 1,125-line HD-MAC test broadcasts were performed in the early 1990s, but did not lead to any established public broadcast service.
Japan remained the only country with successful public broadcast analog HDTV, known as “Hi-vision”, featuring a 5:3 aspect ratio screen with 1,125 interlaced lines (1,035 active lines) at the rate of 60 fields per second. The single satellite transponder MUSE service was turned off on 01 January 2007.
It was not until the early 2000s that technology had progressed enough to deliver sufficient storage capacity and processing power to support compression algorithms powerful enough to make HDTV affordable for consumers[who?] and profitable for broadcasters and other program makers. The main enabling factor was the transition from analog to digital TV standards.
[edit] Modern digital compression and standardization
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Please update the article to reflect recent events / newly available information, and remove this template when finished. |
Digital compression methods such as MPEG-2 and MPEG-4 allow the bandwidth of a single analog TV channel (6 MHz in the US) to carry up to 5 standard-definition or up to 2 high-definition digital TV channels instead.
Most developed nations have plans in place for a transition to digital television, but not necessarily (or exclusively) to HDTV.
For example, on 17th February 2009[update needed], the US intends to terminate all full-power terrestrial analog broadcasting (although some smaller local stations have later deadlines), with both standard definition TV (SDTV) and HDTV being allowed. [8]
Current HDTV broadcast standards include ATSC (North America, parts of South America and South Korea), DVB (Europe, Australia, parts of Asia and Africa) and ISDB-T (Japan, Brazil).
The hoped for standardization of HDTV formats has mostly been achieved[who?].
However, there could be future HDTV interoperability issues — but much less severe than SDTV interoperability issues
- the Chinese HDTV system uses an Intellectual Property free MPEG2 CODEC that may have some coding interoperability issues with current DVB CODECs
- the Brazilian HDTV system uses MPEG-4 (as opposed to MPEG-2, the DVB standard) for the video coding, a potential source of interoperability problems
- However, the fundamental DVB resolution (720, 1080) and frame rate specifications (24, 25, 30/29.97) have not been modified by any modified DVB HDTV system in current use or development
- HDTV universally provides a 5.1-channel surround sound audio using e.g. the Dolby Digital (AC-3) format
[edit] HDTV sources
The rise in popularity of large screens and projectors has made the limitations of conventional Standard Definition TV (SDTV) increasingly evident. An HDTV compatible television set will not improve the quality of SDTV channels. It will make it even worse because of scaling artifacts. To display a superior picture, high definition televisions require a High Definition (HD) signal. Typical sources of HD signals are as follows:
- Over the air with an antenna. Most cities in the US with major network affiliates broadcast over the air in HD. To receive this signal an HD tuner is required. Most newer high definition televisions have an HD tuner built in. For HDTV televisions without a built in HD tuner, a separate set-top HD tuner box can be rented from a cable or satellite company or purchased.
- Cable television companies often offer HDTV broadcasts as part of their digital broadcast service. This is usually done with a set-top box or CableCARD issued by the cable company. Alternatively one can usually get the network HDTV channels for free with basic cable by using a QAM tuner built into their HDTV or set-top box. Some cable carriers also offer HDTV on-demand playback of movies and commonly viewed shows.
- Satellite-based TV companies, such as DirecTV and Dish Network (both in North America), Sky Digital (in the UK and Ireland), Bell ExpressVu and Star Choice (both in Canada) and NTV Plus (in Russia), offer HDTV to customers as an upgrade. New satellite receiver boxes and a new satellite dish are often required to receive HD content.
- Video game systems, such as thePlayStation 3 and Xbox 360, and digital set-top boxes that rely on an Internet connection, such as the Apple TV, can output an HD signal. The Xbox Live Marketplace, iTunes Music Store, and PlayStation Network services offer HD movies, TV shows, movie trailers, and clips for download, but generally at lower bitrates than a Blu-ray Disc.
- Most newer computer graphics cards have either HDMI or DVI interfaces, which can be used to output images or video to an HDTV.
- The optical disc standard Blu-ray Disc (25GB-50GB) can provide enough digital storage to store up to 10 hours of HD video content, depending on encoder settings.[9]
- A DVD-R disc (~4.7GB-9GB) can also provide storage for 20-40 minutes of HD video content, readable by a blu-ray player, depending on encoder settings. [10]
[edit] Notation
HDTV broadcast systems are defined threefold, by:
- The scanning system: progressive scanning (p) or interlaced scanning (i). Progressive scanning simply draws a complete image frame (all the lines) per image refresh, whereas interlaced scanning draws a partial image field (every second line) during a first pass, then fills-in the remaining lines during a second pass, per image refresh. Interlaced scanning requires significantly lower signal/data bandwidth, but an interlaced signal loses half of the vertical resolution and suffers “combing” artifacts when showing a moving subject on a progressive display (although the worst effects can be mitigated by suitable image post-processing known as ‘deinterlacing’). As some compensation, however, interlaced mode provides finer time-sampling, giving two (half-resolution) image samples in the same time interval as one (full-resolution) image sample in progressive mode.
- The number of frames per second or fields per second.
The 720p60 format is 1280 × 720 pixels progressive scanning with 60 fields per second (120 Hz). The 1080i50 format is 1920 × 1080 pixels (ie 2 MP) interlaced scanning with 50 fields per second. Sometimes interlaced fields are called half-frames, but they are not, because two fields of one frame are temporally shifted. Frame pulldown and segmented frames are special techniques that allow transmitting full frames via an interlaced video stream.
For commercial naming of the product, either the frame rate or the field rate is often dropped, e.g. a “1080i television set” label indicates only the image resolution.[11] Often, the rate is inferred from the context, usually assumed to be either 50 or 60 Hz, except for 1080p, which denotes 1080p24, 1080p25, and 1080p30, but may include 1080p50 and 1080p60 in the future.
A frame or field rate can also be specified without a resolution. For example 24p means 24 progressive scan frames per second, and 50i means 25 interlaced frames per second consisting of 50 interlaced fields per second. Most HDTV systems support some standard resolutions and frame or field rates. The most common are noted below.
[edit] Standard Display Resolutions
Standard Definition usually refers to 480 vertical lines of resolution or more.
| Resolution (W×H) |
Active Frame (W×H) |
Canonical Name(s) |
Pixels (Advertised Megapixels) |
Display Aspect Ratio (X:Y) |
Pixel Aspect Ratio – Standard “4:3″ (X:Y) |
Pixel Aspect Ratio – Widescreen “16:9″ (X:Y) |
Description |
| ITU-R BT.601 |
MPEG-4 |
ITU-R BT.601 |
MPEG-4 |
| 720×480 |
710.85×486 |
480i/p |
345,600 (0.3) |
3:2 |
4320:4739 |
10:11 |
5760:4739 |
40:33 |
Used for 525-line/ (60 * 1000/1001) Hz video, e.g. NTSC-M |
| 720×576 |
702×576 |
576i/p |
414,720 (0.4) |
5:4 |
128:117 |
12:11 |
512:351 |
16:11 |
Used for 625-line/50 Hz video, e.g. PAL-I |
When resolution is considered, both the resolution of the transmitted signal and the (native) displayed resolution of a TV set are taken into account. Most HDTV sets contain video scalers and will “upscale” or “upconvert” the transmitted signal to that of the set’s native format.
Sometimes the progressive versions of these video formats are referred to as EDTV, or “Enhanced Definition Television.” This is slightly misleading, for although a progressive frame contains double the image information as that of an interlaced frame, Standard Definition is already capable of displaying progressive frames, for example in MPEG video with the appropriate “Progressive” flag set. Despite this, 480p/576p signals are not currently broadcast.
[edit] High-Definition Display Resolutions
High Definition usually refers to 720 vertical lines of video format resolution or more.
| Video Format Supported |
Native Resolution (W×H) |
Pixels (Advertised Megapixels) |
Aspect Ratio (X:Y) |
Description |
| Image |
Pixel |
720p
1280×720 |
1024×768
XGA |
786,432 (0.8) |
16:9 |
4:3 |
Typically a PC resolution XGA; also exists as a standardized “HD-Ready” TV on the Plasma display with non-square pixels. |
| 1280×720 |
921,600 (0.9) |
16:9 |
1:1 |
Typically one of the PC resolutions on WXGA, also used for 750-line video, as defined in SMPTE 296M, ATSC A/53, ITU-R BT.1543, Digital television, DLP and LCOS projection HDTV displays. |
1366×768
WXGA |
1,049,088 (1.0) |
683:384
(Approx 16:9) |
1:1
Approx |
Typically a TV resolution WXGA; also exists as a standardized HDTV displays as (HD Ready 720p,1080i), TV that used on LCD HDTV displays. |
1080i
1920×1080 |
1280×1080 |
1,382,400 (1.4) |
32:27
(Approx 16:9) |
3:2 |
Non-standardized “HD Ready“, TV. Used on HDTV Plasma display with non-square pixels. |
1080p
1920×1080 |
1920×1080 |
2,073,600 (2.1) |
16:9 |
1:1 |
A standardized HDTV displays as (HD Ready 1080p) TV, that used on LCD HDTV displays. Used for 1152-line video, as defined in SMPTE 274M, ATSC A/53, ITU-R BT.709. |
2160p
3840×2160 |
3840×2160 |
8,294,400 (8.3) |
16:9 |
1:1 |
Quad HDTV for DCI Cinema 4k standard format, (Currently, there is no HD Ready 2160p Quad HDTV format until 2015). |
A common native resolution used in HD Ready LCD TV panels is 1366 x 768[12] pixels instead of the ATSC Standard 1280 x 720 pixels. This is due to maximization of manufacturing yield and resolution of VGA, VRAM that comes with a 768 pixel format. Hence, LCD manufacturers adopt the 16:9 ratio compatible for the HD Ready 1080p video standard. Nevertheless, every HDTV has an overscan processing chipset to fix resolution scaling and color rendering, eg LG XD Engine, SONY BRAVIA Engine. Only when viewing 1080i/1080p HD contents under HD Ready 1080p where there is true pixel-for-pixel reproduction, and for HD ready LCD TV, do some signals undergo a scaling process which results in a 3-5% loss of picture.
| Video Format Supported |
Screen Resolution (W×H) |
Pixels (Advertised Megapixels) |
Aspect Ratio (X:Y) |
Description |
| Image |
Pixel |
720p
1280×720 |
1248×702
Clean Aperture |
876,096 (0.9) |
16:9 |
1:1 |
Used for 750-line video with raster artifact/overscan compensation, as defined in SMPTE 296M. |
1080p
1920×1080 |
1888×1062
Clean Aperture |
2,001,280 (2.0) |
16:9 |
1:1 |
Used for 1152-line video with raster artifact/overscan compensation, as defined in SMPTE 274M. |
1080i
1920×1080 |
1440×1080
HDCAM/HDV |
1,555,200 (1.6) |
4:3 |
4:3:1 |
Used for anamorphic 1152-line video in the HDCAM and HDV formats introduced by Sony and defined (also as a luminance subsampling matrix) in SMPTE D11. |
It should be noted that the numbers used for “HD-Ready” image resolutions do not constitute acceptable 750- or 1152-line video signals in most standards-compliant hardware; in this respect terms such as “720p” and “1080p” are mostly used for advertising, though that does not necessarily mean that HD-Ready TVs labeled in this manner are incapable of accepting those formats as input.
Additionally, the “Clean Aperture” numbers are almost always contained within the frames of their respective “Production Aperture” numbers (e.g., a 1888×1062 rectangle would be contained within a 1920×1080 frame). This is to maintain compatibility with analogue signals, which can often become distorted close to the edge of the frame. It also increases the chance that a digital signal being played on overscan-enabled equipment will display the entire picture visibly.
[edit] Standard frame or field rates
- 23.976p (allow easy conversion to NTSC)
- 24p (cinematic film)
- 25p (PAL, SECAM DTV progressive material)
- 30p (29.97p in drop frame) (NTSC DTV progressive material)
- 50i (PAL & SECAM)
- 50p (PAL, SECAM DTV progressive material)
- 60i (59.94i in drop frame) (NTSC, PAL-M)
- 60p (59.94p in drop frame) (NTSC DTV progressive material)
[edit] Broadcast station format considerations
| Close-up view |
 |
 |
| HDTV resolution |
SDTV resolution |
At the least, HDTV has twice the linear resolution of standard-definition television (SDTV), thus showing greater detail than either analog television or regular DVD. The technical standards for broadcasting HDTV also handle the 16:9 aspect ratio images without using letterboxing or anamorphic stretching, thus increasing the effective image resolution.
The optimum format for a broadcast depends upon the type of videographic recording medium used and the image’s characteristics. The field and frame rate should match the source and the resolution. A very high resolution source may require more bandwidth than available in order to be transmitted without loss of fidelity. The lossy compression that is used in all digital HDTV storage and transmission systems will distort the received picture, when compared to the uncompressed source.
[edit] Types of media
Standard 35mm photographic film used for cinema projection has higher resolution than HDTV systems, and is exposed and projected at a rate of 24 frames per second. To be shown on television in PAL-system countries, cinema film is scanned at the TV rate of 25 frames per second, causing an acceleration of 4.1 percent, which is generally considered acceptable. In NTSC-system countries, the TV scan rate of 30 frames per second would cause a perceptible acceleration if the same were attempted, and the necessary correction is performed by a technique called 3:2 pull-down: over each successive pair of film frames, one is held for three video fields (1/20 of a second) and the next is held for two video fields (1/30 of a second), giving a total time for the two frames of 1/12 of a second and thus achieving the correct average film frame rate.
- See also: Telecine
Non-cinematic HDTV video recordings intended for broadcast are typically recorded either in 720p or 1080i format as determined by the broadcaster. 720p is commonly used for Internet distribution of high-definition video, because all computer monitors operate in progressive-scan mode. 720p also imposes less strenuous storage and decoding requirements compared to both 1080i and 1080p. 1080p is usually used for Blu-ray Disc.
[edit] List of stations
[edit] Technical details
One of the first DVB-S2 tuner cards.
Networked dual-tuner for ATSC and QAM
HDTV signals and colorimetry are defined by Rec. 709. MPEG-2 is most commonly used as the compression codec for digital HDTV broadcasts. Although MPEG-2 supports up to 4:2:2 YCbCr chroma subsampling and 10-bit quantization, HD broadcasts use 4:2:0 and 8-bit quantization to save bandwidth. Some broadcasters also plan to use MPEG-4 AVC, such as the BBC which is trialing such a system via satellite broadcast, which will save considerable bandwidth compared to MPEG-2 systems. Some German broadcasters already use MPEG-4 AVC together with DVB-S2 (Pro 7, Sat.1 and Premiere). Although MPEG-2 is more widely used at present, it seems likely that in the future all European HDTV may be MPEG-4 AVC, and Norway, which is currently in the progress of implementing digital television broadcasts, is using MPEG-4 AVC for present SD Digital as well as for future HDTV on terrestrial broadcasts. In parts of Sweden the standard is already in use for HDTV terrestrial broadcasting, reaching about 25-30% of the population. Brasil was the first country in the American continent to begin broadcasting H.264 AVC video and HE-AAC audio as the main program (or multi) compression and the same H.264 AVC in LDTV 240p using AAC-LC as audio for mobile DTV devices, not only mobile phones.
HDTV is capable of “theater-quality” audio because it uses the Dolby Digital (AC-3) format to support “5.1″ surround sound. The pixel aspect ratio of native HD signals is a “square” 1.0, in which each pixel’s height equals its width. New HD compression and recording formats such as HDV use rectangular pixels to save bandwidth and to open HDTV acquisition for the consumer market. For more technical details see the articles on HDV, ATSC, DVB, and ISDB but the ISDB-Tb used primarily in Brasil uses HE-AAC that is more flexible than AC-3 and lower royalty fees..
Television studios as well as production and distribution facilities, use the HD-SDI SMPTE 292M interconnect standard (a nominally 1.485 Gbit/s, 75-ohm serial digital interface) to route uncompressed HDTV signals. The native bitrate of HDTV formats cannot be supported by 6-8 MHz standard-definition television channels for over-the-air broadcast and consumer distribution media, hence the widespread use of compression in consumer applications. SMPTE 292M interconnects are generally unavailable in consumer equipment, partially due to the expense involved in supporting this format, and partially because consumer electronics manufacturers are required (typically by licensing agreements) to provide encrypted digital outputs on consumer video equipment, for fear that this would aggravate the issue of video piracy.
Newer dual-link HD-SDI signals are needed for the latest 4:4:4 camera systems (Sony Cinealta F23 & Thomson Viper), where one link/coax cable contains the 4:2:2 YCbCr info and the other link/coax cable contains the additional 0:2:2 CbCr information.
[edit] Advantages of HDTV expressed in non-technical terms
High-definition television (HDTV) yields a better-quality image than standard television does, because it has a greater number of lines of resolution. The visual information is some 2-5 times sharper because the gaps between the scan lines are narrower or invisible to the naked eye.
The lower-case “i” appended to the numbers denotes interlaced; the lower-case “p” denotes progressive. The interlaced scanning method, the 1,080 lines of resolution are divided into two, the first 540 lines are painted on a frame, the second 540 lines are painted on a second frame, reducing the bandwidth. The progressive scanning method simultaneously displays all 1,080 lines of resolution at 60 frames per second, on a greater bandwidth. (See: An explanation of HDTV numbers and laymen’s glossary)
Often, the broadcast HDTV video signal soundtrack is Dolby Digital 5.1 surround sound, enabling full, surround sound capabilities, while STBC television signals include either monophonic or stereophonic audio, or both. Stereophonic broadcasts can be encoded with Dolby Surround audio signal. Brasil opted to upgrade the ISDB-T Japanese standard to H.264 AVC Mpeg4 part 10 in the video compression and HE-AAC for audio compression because Dolby is not open and the royalty fees are more expensive than that of Mpeg4 H.264 AVC and renamed the upgraded standard to ISDB-Tb that now became the International ISDB-T standard.
[edit] Disadvantages of HDTV expressed in non-technical terms
In practice, the best possible HD quality is not usually achieved. The main problem is that many operators do not follow HDTV specifications fully. They may use slower bitrates or lower resolution to pack more channels within the limited bandwidth, reducing video quality.[13] The operators may use a format that is different from the original programming, introducing generation loss artifacts in the process of re-encoding.[14] Also, image quality may be lost if the television is not properly connected to the input device or not properly configured for the input’s optimal performance, which may be difficult because of customer confusion regarding connections.
Appropriate cabling must be used. In most cases, HDMI component cables are required. These are often more expensive. For instance, if composite or S-Video cables are used for connections from a cable box or satellite dish then only an SDTV quality picture will be seen. HDMI cables provide the best picture and sound but are also generally more expensive than component cables.
As high-definition video broadcasts are digital, the disadvantages of digital video broadcasting also apply. For example, digital video responds differently to analogue video when subject to interference. Unlike in analogue television broadcasting, in which interference causes only gradual image and sound degradation, interference in a digital television broadcast will freeze, skip, or display “garbage” information. This problem is particularly pronounced in the 8VSB modulation standard used for over-the-air transmission in the United States, which is highly sensitive to dynamic multipath interference that may be introduced by moving objects between the transmitting and receiving antennas. For instance, it is impossible to receive a 8VSB-modulated HDTV signal in a moving vehicle, and it may be difficult to maintain reception during high winds in locations where large trees are situated in the line between broadcasting antenna and receiver.
In order to view HDTV broadcasts, viewers may have to upgrade their TVs at some expense. Adding a new aspect ratio makes for consumer confusion if a display is capable of one or more ratios but must be switched to the correct one by the user. Traditional standard definition programs and feature films (mostly movies from before 1953) originally filmed in the standard 4:3 ratio, when displayed correctly on a HDTV monitor, will have empty display areas to the left and right of the image. Many consumers aren’t satisfied with this unused display area and choose instead to distort their standard definition shows by stretching them horizontally to fill the screen, giving everything the appearance of being too wide or not tall enough. Alternatively, viewers may choose to zoom the image which removes content that was on the top and bottom of the original TV show.[15]
Broadcasters may demand, or cable-television operators may elect, to place HD signals in a premium band that requires higher cable fees. Some satellite companies may offer local HD channels as a service at additional cost (transmission comes from satellite). This leads some broadcasters to offer on-air broadcasts of local HD signals as a premium service to subscribers. Viewers may be denied some television channels that they expected, be allowed only access to the non-digital, and obviously sub-standard non-digital signal, or have to install an antenna to receive the digital broadcasts. Such issues entail economic and legal disputes more than technology.
Another disadvantage of HDTV compared to traditional television has been consumer confusion stemming from the different standards and resolutions, such as 1080i, 1080p, and 720p. Complicating the matter have been the changes in television connections from component video, to DVI, then to HDMI. Finally, the HD DVD vs. Blu-ray Disc high definition storage format war for a period of time created confusion for consumers. This particular format war was recently “settled” with Blu-ray emerging as the victorious standard.
[edit] Contemporary systems
-
Components of a typical satellite HDTV system:
1. HDTV Monitor
2. HD satellite receiver
3. Standard satellite dish
4. HDMI cable, DVI-D and audio cables, or audio and component video cables
Besides a HD-ready television set, other equipment is needed to view HD television. Cable-ready TV sets can display HD content without using an external box. They have a QAM tuner built-in and/or a card slot for inserting a CableCARD.[16].
High-definition image sources include terrestrial broadcast, direct broadcast satellite, digital cable, the high definition disc BD, internet downloads, and the PlayStation 3 and Xbox 360 game consoles.
[edit] Recording and compression
-
HDTV can be recorded to D-VHS (Digital-VHS or Data-VHS), W-VHS (analog only), to a HDTV-capable digital video recorder (for example DirecTV‘s high-definition Digital video recorder, Sky HD‘s set-top box, Dish Network‘s VIP 622 or VIP 722 high-definition Digital video recorder receivers, or TiVo‘s Series 3 or HD recorders), or a HDTV-ready HTPC. Some cable boxes are capable of receiving or recording two broadcasts at a time in HDTV format, and HDTV programming, some free, some for a fee, can be played back with the cable company’s on-demand feature. The massive amount of data storage required to archive uncompressed streams make it unlikely that an uncompressed storage option will appear in the consumer market soon. Realtime MPEG-2 compression of an uncompressed digital HDTV signal is also prohibitively expensive for the consumer market at this time, but should become inexpensive within several years (although this is more relevant for consumer HD camcorders than recording HDTV). Analog tape recorders with bandwidth capable of recording analog HD signals such as W-VHS recorders are no longer produced for the consumer market and are both expensive and scarce in the secondary market.
In the United States, as part of the FCC’s “plug and play” agreement, cable companies are required to provide customers who rent HD set-top boxes with a set-top box with “functional” Firewire (IEEE 1394) upon request. None of the direct broadcast satellite providers have offered this feature on any of their supported boxes, but some cable TV companies have. As of July 2004, boxes are not included in the FCC mandate. This content is protected by encryption known as 5C.[17] This encryption can prevent duplication of content or simply limit the number of copies permitted, thus effectively denying most if not all fair use of the content.
[edit] Table of terrestrial HDTV transmission systems
Main characteristics of three HDTV systems
| Systems |
ATSC |
DVB-T |
ISDB-T |
| Source coding |
| Video |
Main Profile syntax of ISO/IEC 13818-2 (MPEG-2 – Video) |
| Audio |
ATSC Standard A/52 (Dolby AC-3) |
As defined in ETSI DVB TS 101 154 – as H.264 AVC and/or ISO/IEC 13818-2 (MPEG-2 – Layer II Audio) and/or Dolby AC-3 |
ISO/IEC 13818-7 (MPEG-2 – AAC Audio) |
| Transmission system |
| Channel coding |
|
| Outer coding |
R-S (207, 187, t = 10) |
R-S (204, 188, t = 8) |
| Outer interleaver |
52 R-S block |
convolutional (I=12, M=17, J=1) |
12 R-S block |
| Inner coding |
rate 2/3 Trellis code |
Punctured convolution code(PCC): rate 1/2, 2/3, 3/4, 5/6, 7/8; constraint length = 7, Polynomials (octal) = 171, 133 |
| Inner interleaver |
12 to 1 Trellis code |
bit-wise, frequency, selectable time |
| Data randomization |
16-bit PRBS |
| Modulation |
8VSB (Only used for over the air transmission)
16VSB (Designed for cable, but rejected by the cable industry, cable TV uses 64QAM or 256QAM modulation as a de facto standard) |
COFDM
QPSK, 16QAM and 64QAM
Hierarchical modulation: multi-resolution constellation (16QAM and 64QAM)
Guard interval: 1/32, 1/16, 1/8 & 1/4 of OFDM symbol
Two modes: 2k and 8k FFT |
BST-COFDM with 13 frequency segments
DQPSK, QPSK, 16QAM and 64QAM
Hierarchical modulation: choice of three different modulations on each segment
Guard interval: 1/32, 1/16, 1/8 & 1/4 of OFDM symbol
Three modes: 2k, 4k and 8k FFT |
[edit] TV resolution
| [hide]
Digital Video Resolutions |
|
| Designation |
| Usage Examples |
Definition (lines) |
Rate (Hz) |
| Interlaced (fields) |
Progressive (frames) |
|
|
| Low; MP@LL |
|
|
| Standard; MP@ML |
|
|
| Enhanced |
|
|
| High; MP@HL |
|
|
|
|
|
| This table illustrates total horizontal and vertical pixel resolution via box size. It does not accurately reflect the screen or pixel shape (aspect ratio) of these formats, which is either 4:3, or 16:9. |
|
[edit] See also
[edit] References
Cited references
- ^ “HDTV in the Russian Federation: problems and prospects of implementation (in Russian)“.
- ^ “Researchers Craft HDTV’s Successor“.
- ^ “Digital TV Tech Notes, Issue #2“.
- ^ “Digital TV Tech Notes, Issue #41“.
- ^ The Grand Alliance includes AT&T, General Instrument, MIT, Philips, Sarnoff, Thomson, and Zenith)
- ^ Carlo Basile et al. (1995). “The U.S. HDTV standard: the Grand Alliance”. IEEE Spectrum (4): 36–45.
- ^ “Digital TV Tech Notes, Issue #1“.
- ^ Howstuffworks “How Digital Television Works”
- ^ Howstuffworks “How HD-DVD Works”
- ^ “Basic Blu-Ray Authoring with HDV source”
- ^ “The HDTV Progressive Frame Rate Clarification Initiative“.
- ^ “1366×768 resolution problems on HDTV, HD-Ready, and High Definition TV“.
- ^ “DirecTV HD Image Quality“.
- ^ “DirecTV’s HD future is MPEG-4“.
- ^ HDTV display modes: Information and Much More from Answers.com
- ^ “HDTV information“.
- ^ “5C Digital Transmission Content Protection White Paper” (pdf) (1998-07-14).
General references
[edit] External links
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