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| Tipo de medio | Disco óptico |
|---|---|
| Codificación | Vídeo + audio MPEG-1 |
| Capacidad | Hasta 800 MB / 80 minutos de video |
| Leer mecanismo | Láser semiconductor de longitud de onda de 780 nm |
| Estándar | libro Blanco |
| Desarrollado por | Philips , Sony , Panasonic , JVC |
| Uso | almacenamiento de audio y video |
| Extendido a | SVCD |
| Liberado | 1993 |
| Discos ópticos |
|---|
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Video CD (abreviado como VCD y también conocido como Compact Disc Digital Video ) es un formato de video doméstico y el primer formato para distribuir películas en discos ópticos estándar de 120 mm (4.7 pulgadas). El formato fue ampliamente adoptado en el sudeste asiático , Asia central y Medio Oriente , reemplazando a los sistemas VHS y Betamax en las regiones hasta que el DVD-Video finalmente se volvió asequible a fines de la década de 2000.
El formato es un formato de datos digitales estándar para almacenar video en un disco compacto . Los VCD se pueden reproducir en reproductores de VCD dedicados y se pueden reproducir ampliamente en la mayoría de los reproductores de DVD , computadoras personales y algunas consolas de videojuegos . Sin embargo, son menos reproducibles en algunos reproductores de Blu-ray Disc , audio de vehículos con soporte para DVD / Blu-ray y consolas de videojuegos como Sony PlayStation y Xbox debido a la falta de compatibilidad con versiones anteriores del formato MPEG-1 anterior o la incapacidad. para leer MPEG-1 en .dat archivos junto con MPEG-1 en archivos MPEG-1 estándar.
El estándar Video CD fue creado en 1993 [1] [2] por Sony , Philips , Matsushita y JVC ; se conoce como el estándar del Libro Blanco . El formato MPEG-1 también se lanzó ese mismo año.
Aunque han sido reemplazados por otros medios, a partir de 2021 [update], los VCD continúan vendiéndose como un formato de video de bajo costo en territorios en desarrollo, como Asia. [ cita requerida ]
Breve historia [ editar ]
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LaserDisc estuvo disponible por primera vez en el mercado, en Atlanta, Georgia , el 15 de diciembre de 1978. [3] Este disco de 30 cm (12 pulgadas) podía contener una hora de audio y video analógicos (el audio digital se agregó unos años más tarde) en cada lado. El LaserDisc proporcionó una calidad de imagen casi el doble que la de las cintas VHS y una calidad de audio analógica muy superior a la del VHS.
Más tarde, Philips se asoció con Sony para desarrollar un nuevo tipo de disco, el disco compacto o CD. Introducido en 1982 en Japón (1983 en los EE. UU. Y Europa), el CD tiene aproximadamente 120 mm (4,7 pulgadas) de diámetro y es de una sola cara. El formato se diseñó inicialmente para almacenar sonido digitalizado y resultó ser un éxito en la industria de la música.
Unos años más tarde, Philips decidió dar a los CD la capacidad de producir video, utilizando la misma tecnología que su contraparte LaserDisc. Esto llevó a la creación de CD Video (CD-V) en 1987. Sin embargo, el pequeño tamaño del disco impidió significativamente la capacidad de almacenar video analógico; por lo tanto, solo 5 minutos de información de imagen podrían caber en la superficie del disco (a pesar de que el audio era digital). Por lo tanto, la distribución de CD-V se limitó a presentar videos musicales y pronto se suspendió en 1991.
A principios de la década de 1990, los ingenieros pudieron digitalizar y comprimir señales de video, mejorando enormemente la eficiencia del almacenamiento. Debido a que este nuevo formato podía contener 74/80 minutos de audio y video en un disco de 650/700 MB, el lanzamiento de películas en discos compactos finalmente se convirtió en una realidad. Se obtuvo capacidad adicional sacrificando la corrección de errores (se creía que los errores menores en el flujo de datos pasarían desapercibidos para el espectador). Este formato se denominó Video CD o VCD.
VCD disfrutó de un breve período de éxito, con algunos largometrajes importantes que se estrenaron en el formato (generalmente como un conjunto de 2 discos). Sin embargo, la introducción del disco CD-R y las grabadoras asociadas detuvieron el lanzamiento de largometrajes en sus pistas porque el formato VCD no tenía medios para evitar que se hicieran copias no autorizadas (y perfectas). [ cita requerida ] Sin embargo, a partir de 2013, los [update]VCD todavía se están lanzando en varios países de Asia, pero ahora con protección de copia. [ cita requerida ]
The development of more sophisticated, higher capacity optical disc formats yielded the DVD format, released only a few years later with a copy protection mechanism. DVD players use lasers that are of shorter wavelength than those used on CDs, allowing the recorded pits to be smaller, so that more information can be stored. The DVD was so successful that it eventually pushed VHS out of the video market once suitable recorders became widely available. Nevertheless, VCDs made considerable inroads into developing nations, where they are still in use today due to their cheaper manufacturing and retail costs.[citation needed]
Technical specifications[edit]
Structure[edit]
Video CDs comply with the CD-i Bridge format, and are authored using tracks in CD-ROM XA mode. The first track of a VCD is in CD-ROM XA Mode 2 Form 1, and stores metadata and menu information inside an ISO 9660 filesystem. This track may also contain other non-essential files, and is shown by operating systems when loading the disc. This track can be absent from a VCD, which would still work but would not allow it to be properly displayed in computers.[4]
The rest of the tracks are usually in CD-ROM XA Mode 2 Form 2 and contain video and audio multiplexed in an MPEG program stream (MPEG-PS) container, but CD audio tracks are also allowed.[4] Using Mode 2 Form 2 allows roughly 800 megabytes of VCD data to be stored on one 80 minute CD (versus 700 megabytes when using CD-ROM Mode 1). This is achieved by sacrificing the error correction redundancy present in Mode 1. It was considered that small errors in the video and audio stream pass largely unnoticed. This, combined with the net bitrate of VCD video and audio, means that almost exactly 80 minutes of VCD content can be stored on an 80-minute CD, 74 minutes of VCD content on a 74-minute CD, and so on. This was done in part to ensure compatibility with existing CD drive technology, specifically the earliest "1x" speed CD drives.
Video[edit]
Video specifications[5]
- Compression: MPEG-1
- Aspect Ratio: 4:3
- Resolution:
- NTSC: 352×240
- PAL/SECAM: 352×288
- Framerate:
- NTSC: 29.97 or 23.976 frames per second
- PAL/SECAM: 25 frames per second
- Bitrate: 1,150 kilobits per second
- Rate Control: constant bitrate
Although many DVD video players support playback of VCDs, VCD video is only compatible with the DVD-Video standard if encoded at 29.97 frames per second or 25 frames per second.
The 352×240 and 352×288 (or SIF) resolutions were chosen because it is half the horizontal and vertical resolution of NTSC video, and half the horizontal resolution of PAL (the vertical resolution of PAL already being half of the 576 active lines). This is approximately half the resolution of an analog VHS tape which is ~330 horizontal and 480 vertical (NTSC) or 330×576 (PAL).
Audio[edit]
Audio specifications[5]
- Compression: MPEG-1 Audio Layer II
- Sample Frequency: 44,100 hertz (44.1 kHz)
- Output: Dual channel, stereo, or Dolby Surround
- Bitrate: 224 kilobits per second
- Rate Control: Constant bitrate
As with most CD-based formats, VCD audio is incompatible with the DVD-Video standard due to a difference in sampling frequency; DVDs require 48 kHz, whereas VCDs use 44.1 kHz.
Advantages of compression[edit]
By compressing both the video and audio streams, a VCD is able to hold 74 minutes of picture and sound information, the same duration as a standard 74 minute audio CD. The MPEG-1 compression used records mostly the differences between successive video frames, rather than write out each frame individually. Similarly, the audio frequency range is limited to those sounds most clearly heard by the human ear.
Other features[edit]
The VCD standard also features the option of DVD-quality still images/slide shows with audio, at resolutions of 704×480 (NTSC) or 704×576 (PAL/SECAM). Version 2.0 also adds the playback control (PBC), featuring a simple menu like DVD-Video.
Similar formats[edit]
CD-i Digital Video[edit]
Shortly before the advent of White Book VCD, Philips started releasing movies in the Green Book CD-i format, calling the subformat CD-i Digital Video (CD-i DV). While these used a similar format (MPEG-1), due to minor differences between the standards these discs are not compatible with VCD players. Philips' CD-i players with the Full Motion Video MPEG-1 decoder cartridge would play both formats. Approximately 30 CD-i DV titles were released before the company switched to the current VCD format for publishing movies in 1994.
XVCD[edit]
XVCD (eXtended Video CD) is the name generally given to any format that stores MPEG-1 video on a compact disc in CD-ROM XA Mode 2 Form 2, but does not strictly follow the VCD standard in terms of the encoding of the video or audio.
A normal VCD is encoded to MPEG-1 at a constant bit rate (CBR), so all scenes are required to use exactly the same data rate, regardless of complexity. However, video on an XVCD is typically encoded at a variable bit rate (VBR), so complex scenes can use a much higher data rate for a short time, while simpler scenes will use lower data rates. Some XVCDs use lower bitrates in order to fit longer videos onto the disc, while others use higher bitrates to improve quality. MPEG-2 may be used instead of MPEG-1.
To further reduce the data rate without significantly reducing quality, the size of the GOP can be increased, a different MPEG-1 quantization matrix can be used, the maximum data rate can be exceeded, and the bit rate of the MP2 audio can be reduced or even be swapped out completely for MP3 audio. These changes can be advantageous for those who want to either maximize video quality, or use fewer discs.
KVCD[edit]
KVCD (K Video Compression Dynamics) is an XVCD variant that requires the use of a proprietary quantization matrix, available for non-commercial use. KVCD is notable because the specification recommends a non-standard resolution of 528×480 or 528×576. KVCDs encoded at this resolution are only playable by computers with CD-ROM drives, and a small number of DVD players.[6]
DVCD[edit]
DVCD or Double VCD is a method to accommodate longer videos on a CD. A non-standard CD is overburned to include up to 100 minutes of video. However, some CD-ROM drives and players have problems reading these CDs, mostly because the groove spacing is outside specifications and the player's laser servo is unable to track it.
DVI[edit]
DVI (Digital Video Interactive) is a compression technique that stored 72 minutes of video on a CD-ROM. In 1998, Intel acquired the technology from RCA's Sarnoff Research Labs. DVI never caught on.[7]
SVCD[edit]
Super Video CD is a format intended to be the successor of VCD, offering better quality of image and sound.
Adoption[edit]
In North America[edit]
Video CDs were unable to gain acceptance as a mainstream format in North America, chiefly because the established VHS format was less expensive, offered comparable video quality, and could be recorded over.[8] The advent of recordable CDs, inexpensive recorders, and compatible DVD players spurred VCD acceptance in the US in the late 1990s and early 2000s.[9] However, DVD burners and DVD-Video recorders were available by that time, and equipment and media costs for making DVD-Video fell rapidly. DVD-Video, with its longer run time and much higher quality, quickly overshadowed VCD in areas that could afford it. In addition many early DVD players could not read recordable (CD-R) media,[10] and this limited the compatibility of home-made VCDs. Almost every modern stand-alone DVD-Video player can play VCDs burned on recordable media.[citation needed]
In Asia[edit]
The VCD format was very popular throughout Asia[11](except Japan and South Korea) in the late 1990s through the 2000s, with 8 million VCD players sold in China in 1997 alone,[12]and more than half of all Chinese households owning at least one VCD player by 2005.[13] However, popularity has declined over the years, as the number of Hong Kong factories that produced VCDs dropped from 98 in 1999 to 26 in 2012.[14]
This popularity was due, in part, to most households not already owning VHS players when VCDs were introduced, the low price of the players, their tolerance of high humidity (a notable problem for VCRs), easy storage and maintenance, and the lower-cost media.[9] Western sources have cited unauthorized content as a principal incentive for VCD player ownership.[15][16][17]
VCDs are often produced and sold in Asian countries and regions, such as Mainland China, Taiwan, Hong Kong, Singapore, Malaysia, Thailand, Brunei, Myanmar, Indonesia, Philippines, Vietnam, India, Turkey, Pakistan and Bangladesh. In many Asian countries, major Hollywood studios (and Asian home video distributors) have licensed companies to officially produce and distribute the VCDs, such as MCA Home Video in Pakistan, Intercontinental Video Ltd. of Hong Kong, Sunny Video in Malaysia, Vision Interprima Pictures in Indonesia, CVD International and Pacific Marketing and Entertainment Group in Thailand, Excel Home Video in India, Berjaya-HVN and InnoForm Media in both Malaysia and Singapore, Scorpio East Entertainment in Singapore, as well as VIVA Video, Magnavision Home Video, and C-Interactive Digital Entertainment in the Philippines. Legal Video CDs can often be found in established video stores and major book outlets in most Asian countries. They are typically packaged in jewel cases like commercial CDs, though higher-profile films may be released in keep cases, differentiated by the VCD logo.
In Asia, the use of VCDs as carriers for karaoke music is very common. One channel would feature a mono track with music and singing, another channel a pure instrumental version for karaoke singing. Prior to this, karaoke music was carried on laserdiscs.
Worldwide trends[edit]
VCD's growth has slowed in areas that can afford DVD-Video, which offers most of the same advantages, as well as better picture quality[18](higher resolution with fewer digital compression artifacts) due to its larger storage capacity. However, VCD has simultaneously seen significant new growth in emerging economies like India, Indonesia, South America and Africa as a low-cost alternative to DVD. As of 2004, the worldwide popularity of VCD was increasing.[19][20]
Compared with VHS[edit]
Overall picture quality is intended to be comparable to VHS video.[21]Poorly compressed VCD video can sometimes be of lower quality than VHS video, for example exhibiting VCD block artifacts[22] (rather than the analog noise seen in VHS sources), but does not deteriorate further with each use. Producing video CDs involves stripping out high- and low-frequency sounds from the video, resulting in lower audio quality than VHS.[22] While both formats need fast-forwarding to find certain scenes, rewinding to the beginning upon reaching the end is not required in VCD. The resolution is just half below that of common VHS resolution.
Video CDs do not come with closed captioning (on-screen text to aid viewers with hearing problems). When watching a film that exceeds 74 minutes (nearly 1¼ hours), which is the maximum video capacity of one disc, a viewer has to change the disc upon reaching halfway (unless the discs are played on a VCD changer that can hold multiple discs and play them automatically in succession), whereas a single VHS tape can hold 3½ hours of continuous video (though as of 2014, 10-hour VHS tapes are available).
Compared with DVD[edit]
When playing a DVD, the viewer is brought to a main menu which gives them options (watch the feature film, view "deleted scenes", play some special applications, etc.). VCDs are usually straightforward, playing them often goes directly to the video with extras (mostly trailers and commercials) taking place before or after it, like on a VHS cassette.
Subtitles are found on many Asian VCDs but cannot be removed, unlike DVDs. The subtitles are embedded on the video during the encoding process ("hardsubbed"). It is not uncommon to find a VCD with subtitles for two languages.
Though the VCD technology can support it, most films carried on VCDs do not contain chapters, requiring the viewer to fast-forward to resume the program after playback has been stopped. This is mostly because VCD technology is able to start playback at a chapter point but there is nothing to signal the player that the chapter has changed during a program. This can be confusing for the user as the player will indicate that it is still playing chapter 1 when it has played through to chapter 2 or later. Pressing the Next button would cause playback from the beginning of chapter 2. However, preview material is sometimes stored in a separate chapter, followed by a single chapter for the film.
VCDs are often bilingual. Because they feature stereo audio, disc players have an option to play only the left or right audio channel. On some films, they feature English on the left audio channel and Cantonese on the right; more commonly Hong Kong VCDs will feature Mandarin on one channel and Cantonese on the other. This is similar to selecting a language track on a DVD, except it is limited to 2 languages, due to there being only two audio channels (left and right). The audio track effectively becomes monaural.
VCD's most noticeable disadvantage compared to DVD is image quality, due both to the more aggressive compression necessary to fit video into such a small capacity as well as the compression method used. Additionally, VCD movie surround sound capability is limited to Dolby Surround matrixed within the stereo tracks, while DVDs are capable of six channels of discrete surround sound via Dolby Digital AC-3.
Hardware and software support[edit]
Early devices supporting Video CD playback include the Philips CD-i systems and the Amiga CD-32 (albeit via an optional decoder card).[8] Disc playback is also available both natively and as an option on some CD- and DVD-based video game consoles, including Sega Dreamcast, and Sony PlayStation (only on the SCPH-5903 model).
VLC is a free, open-source media player software which supports VCD on Windows, MacOS, Linux and BSD.[23]
Windows Media Player prior to version 9 does not support playing VCD directly. Windows Vista added native support of VCD along with DVD-Video and can launch the preferred application upon insertion. The disc format is also supported natively by Media Player Classic, VLC Media Player and MPlayer.[4]
QuickTime Player also does not support playing VCD directly, though it can play the .DAT files (stored under \MPEGAV for video and audio data) reliably,[24] and plugins were available.
Direct access playback support is available within Windows XP MCE, Windows Vista and newer (including Windows 10), classic Mac OS, BSD, macOS, and Linux among others, either directly or with updates and compatible software.
Most DVD players are compatible with VCDs, and VCD-only players are available throughout Asia, and online through many shopping sites. Some older Blu-ray and HD-DVD players also retained support, as do CBHD players as well. However, most Blu-ray players, most vehicle audio with DVD/Blu-ray support, Xbox, 360, and the Sony PlayStation (2/3/4) cannot play VCDs; this is because while they have backwards playback compatibility with the DVD standard, these player can not read VCD data because the player software does not have support for MPEG-1 video and audio or the player software lacks ability to read MPEG-1 stream in DAT files alongside MPEG-1 stream in standard MPEG files.
See also[edit]
- LaserDisc
- SVCD
- DVD
References[edit]
- ^ Hardware and Software Get an Early Start, Sony, archived from the original on June 25, 2010, retrieved 2008-02-13
- ^ Super Video Compact Disc, A Technical Explanation (PDF) (PDF), Philips System Standards and Licensing, 1998, p. 2, archived from the original (PDF) on 2008-05-28, retrieved 2008-02-13
- ^ "1979: The VideoDisc Is Here!", History of Media Technology, CED magic, retrieved 8 April 2011
- ^ a b c 3.6. VCD playback, MPlayer, retrieved 2018-04-03
- ^ a b "MPEG1 Specifications", icdia.co.uk
- ^ DVD Compatibility Chart, February 25, 2007, retrieved 2008-02-22
- ^ "Definition of: DVI", PC Magazine
- ^ a b "Beginning of the End for Video CD?", Next Generation, Imagine Media (3): 27–28, March 1995
- ^ a b Meyer, Scot (April 26, 2001), "Versatile Video CD's [sic] Get a Foothold in U.S.", New York Times, retrieved 2008-02-12
- ^ Bennett, Hugh (March 1998), DVD-ROM and CD-R: the compatibility question answered - includes related article on reading mixed media, Emedia Professional, archived from the original on 2012-07-12, retrieved 2008-04-26
- ^ Yoshida, Junko (December 1999), "Video CD: China one, West zero", EE Times, archived from the original on 2005-04-09, retrieved 2008-02-12
- ^ Leopold, George; Yoshida, Junko (January 13, 1999), Chinese supplier preps low-cost digital TVs for U.S. market, EE Times, retrieved 2008-02-12
- ^ Chinese families double their incomes in 10 years, China Daily, January 12, 2005, retrieved 2008-02-12
- ^ Amy Nip and Phila Siu (15 November 2012), "Customs criticised for pursuit of outdated CD and VCD piracy", South China Morning Post
- ^ Rosenthal, Elisabeth (November 25, 2001), "Counterfeiters Turn Magic Into Cash", New York Times, retrieved 2008-02-12
- ^ Smith, Craig S. (December 12, 2000), "A Tale of Piracy: How the Chinese Stole the Grinch", New York Times, retrieved 2008-02-12
- ^ Faison, Seth (March 28, 1998), "China Turns Blind Eye to Pirated Disks", New York Times, retrieved 2008-02-12
- ^ Low DVD Prices to Drive up Sales, People's Daily, September 5, 2001, retrieved 2008-02-12
- ^ ESS Technology, Inc. 2003 Annual Report (PDF) (PDF), ESS Technology, 2004, p. 3, archived from the original (PDF) on 2006-03-14, retrieved 2008-02-17
- ^ ESS product to vie with VCD players, People's Daily, August 10, 2004, retrieved 2008-04-01
- ^ Chiariglione, Leonardo (November 6, 1992), MPEG Press Release, London, 6 November 1992, International Organization for Standardization, archived from the original on November 8, 2007, retrieved 2008-03-20
- ^ a b "Correction", Next Generation, Imagine Media (4): 108, April 1995
- ^ "Video CD - VideoLAN Wiki". wiki.videolan.org. Retrieved 2020-08-23.
- ^ "Mac OS X 10.3: Playing Video Compact Disc (VCD) media", apple.com
External links[edit]
- Patent History Video CD Player - published by Philips 2003
- Patent History Video CD Disc - published by Philips 2003
- What is a VCD?
- VCD / SVCD / miniDVD FAQ
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