Video CD (abbreviated as VCD, also known as Compact Disc Digital Video, abbreviated as CDDV) is a home video format and the first format for distributing films on standard optical discs. The format was widely adopted in nearly all of Asia (except for Japan and South Korea), superseding the VHS and Betamax systems in those regions until DVD-Video became more affordable in the 2000s.
The format is a standard digital data format for storing video on a compact disc. VCD discs/disc images are playable in dedicated VCD players and widely playable in most DVD players, personal computers and some video game consoles with an optical disc drive that is programmed to understand VCD discs.
The Video CD standard was created in 1993 by Sony, Philips, Matsushita and JVC; it is referred to as the White Book standard. The MPEG-1 video compression format was also released that same year.
History Predecessors
LaserDisc was first available on the market, in Atlanta, Georgia, on December 15, 1978. This disc could hold an hour of analog audio and video (digital audio was added a few years later) on each side. The LaserDisc provided picture quality nearly double the resolution of VHS tape and analog audio quality far superior to cheap mono VHS recorders (although the difference to the more expensive VHS HiFi stereo recorders was minuscule).
Philips later teamed up with Sony to develop a new type of disc, called the compact disc or CD. Introduced in 1982 in Japan (1983 in the U.S. and Europe), the CD is about in diameter, and is single-sided. The format was initially designed to store digitized sound and proved to be a success in the music industry.
In 1987, Philips released CD Video (CD-V),Despite the similar name, CD Video differed fundamentally from- and was completely incompatible with- the later, all-digital Video CD format. effectively a hybrid format combining analog LaserDisc-compatible videoUnlike some earlier LaserDisc releases, "CD Video"-branded releases included a digital soundtrack. However, the video itself remained analog. alongside separate audio-only CD-compatible tracks on a 12cm CD-sized disc.The "CD Video" brand was also used to market some 20cm and 30cm LaserDiscs that featured digital soundtracks but no actual CD-compatible audio.
However, the disc's small size meant it could only hold six minutes of analog video, restricting it primarily to song-length music videos. CD Video had been discontinued by the early 1990s as Philips concentrated on more promising MPEG-based digital video compression.
Development
By the early 1990s engineers were able to digitize and compress video signals, greatly improving storage efficiency. Because this new format could hold 74/80 minutes of audio and video on a 650/700MB disc, releasing movies on compact discs finally became a reality. Extra capacity was obtained by sacrificing the error correction, as it was believed that minor errors in the datastream would go unnoticed by the viewer. This format was named Video CD or VCD. Despite the similar name it differed fundamentally from—and was incompatible with—the earlier CD Video format.
VCD enjoyed a brief period of success, with a few major feature films being released in the format (usually as a 2 disc set). However the introduction of the CD-R disc and associated recorders stopped the release of feature films in their tracks because the VCD format had no means of preventing unauthorized (and perfect) copies from being made. Despite this, , VCDs were still being produced and released in several countries in Asia with additional copy-protection.
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 such as in Asia where low-cost VCD players as well as pirated copies of films were widespread.
Technical specifications
Structure 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.
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. 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
Video specifications Compression: MPEG-1 Aspect Ratio: 4:3 Resolution: analog NTSC compatible: 352×240 (240p) analog PAL/SECAM compatible: 352×288 (288p) Framerate: analog NTSC compatible : 29.97 or 23.976 frames per second analog PAL/SECAM compatible : 25 frames per second Bitrate: 1,150 kilobits per second (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, when compared to the CCIR 601 specifications (defining the appropriate parameters for digital encoding of NTSC and PAL/SECAM TV signals), are reduced by half in all aspects: height, width, frame-rate, and chrominance.
Audio
Audio specifications Compression: MPEG-1 Audio Layer II (MP2) Sample Frequency: 44,100 hertz (44.1 kHz) Output: Dual channel, stereo, or Dolby Surround Bitrate: 224 kilobits per second (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 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
The VCD standard also features the option of DVD-quality still images/slide shows with audio, at resolutions of 704×480 (480i, analog NTSC compatible) or 704×576 (576i, analog PAL/SECAM compatible). Version 2.0 also adds the playback control (PBC), featuring a simple menu like DVD-Video.
Similar formats
CD-i Digital Video 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 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 KVCD (K Video Compression Dynamics) is an XVCD variant that requires the use of a proprietary quantization matrix, created by Karl Wagner and made available for non-commercial use. In addition to standard VCD resolutions, KVCD allows for non-standard resolutions like 528×480/576, though hardware support for KVCDs authored with these resolutions is limited.
DVCD 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 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.
SVCD Super Video CD is a format intended to be the successor of VCD, offering better quality of image and sound. The format uses MPEG-2 video at 480x480 or 480x576 and supports multiple bitrate and channel options for encoding audio.
Adoption
In North America 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. The advent of recordable CDs, inexpensive recorders, and compatible DVD players spurred VCD acceptance in the US in the late 1990s and early 2000s. 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, and this limited the compatibility of home-made VCDs.
In Asia The VCD format was very popular throughout Asia (except Japan and South Korea) in the late 1990s through the 2000s, with 8 million VCD players sold in China in 1997 alone, and more than half of all Chinese households owning at least one VCD player by 2005. 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.
This popularity was due, in part, to most households not already owning VCRs when VCDs were introduced, the low price of the players, their tolerance of high humidity (a notable problem for VHS tapes), easy storage and maintenance, and the lower-cost media. Western sources have cited unauthorized content as a principal incentive for VCD player ownership.