|Media type||Optical disc|
|Encoding||MPEG-1 video + audio|
|Capacity||Up to 800 MB|
|Read mechanism||780 nm wavelength semiconductor laser|
|Developed by||Sony & Philips Panasonic Samsung|
|Usage||audio and video storage|
|Optical media types|
Video CD (abbreviated as VCD, and also known as View CD, Compact Disc digital video) is a standard digital format for storing video on a Compact Disc. VCDs are playable in dedicated VCD players, most DVD-Video players, personal computers, and some video game consoles.
Overall picture quality is intended to be comparable to VHS video. Poorly compressed VCD video can sometimes be lower quality than VHS video, but VCD exhibits block artifacts (rather than the analog noise seen in VHS sources) and does not deteriorate further with each use.
352x240 (or SIF) resolution was chosen because it is half the vertical, and half the horizontal resolution of NTSC video. 352x288 is similarly one quarter PAL/SECAM resolution. This approximates the (overall) resolution of an analog VHS tape, which, although it has double the number of (vertical) scan lines, has a much lower horizontal resolution.
VCD video is mostly compatible with the DVD-Video standard, except for any video encoded at 23.976 frames per second.
As with most CD-based formats, VCD audio is incompatible with the DVD-Video standard due to a difference in frequency; DVDs require 48 kHz, whereas VCDs use 44.1 kHz.
Video CDs are authored using the Mode 2/XA format, allowing roughly 800 megabytes of VCD data to be stored on one 80 minute CD (versus 700 megabytes when using Mode 1). 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 "1 ×" speed CD drives.
The VCD standard also features the option of DVD-quality still images/slide shows with audio, at resolutions of 704x480 (NTSC) or 704x576 (PAL/SECAM). Version 2.0 also adds the playback control (PBC), featuring a simple menu like DVD-video.
Shortly before the advent of White Book VCD, Philips started releasing movies in the Green Book CD-i format. 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. Only a few CD-i DV titles were released before the company switched to proper VCD format for publishing movies.
XVCD (eXtended Video CD) is the name generally given to any format that stores MPEG-1 video on a compact disc in Mode 2/XA, at VCD resolution, but does not strictly follow the VCD standard.
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.
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 the use of MP3 audio instead of MP2 audio). These changes can be advantageous for those who want to either maximize video quality, or use fewer discs.
KVCD (K Video Compression Dynamics) is a 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 528x480 or 528x576. KVCD discs encoded at this resolution are only playable by computers with CD-ROM drives, and a small number of DVD players. KVCDs of commercial films are commonly distributed as disc images on peer-to-peer networks.
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.
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. Almost every modern stand-alone DVD-Video player can play VCDs burned on recordable media. However, some modern players cannot play VCDs; for instance, the Sony PlayStation 3.
The VCD format was very popular throughout Asia (except Japan) in the late 1990s though 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.
VCDs were often produced and sold in Asian countries and regions such as Mainland China, Taiwan, Hong Kong, Singapore, Malaysia, Thailand, Burma, Indonesia, Philippines, India and Pakistan. 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, ERA of Hong Kong or Sunny Video in Malaysia, Vision in Indonesia, CVD International and Pacific Marketing and Entertainment Group in Thailand, Excel Home Videos in India, Berjaya-HVN and InnoForm Media in both Malaysia and Singapore, as well as VIVA Video, Magnavision, and The Video to C in the Philippines. Legal Video CDs can often be found in established video stores and major book outlets in most Asian countries.
This popularity is, in part, because most households did not already own VHS players when VCDs were introduced, the low price of the players, their tolerance of high humidity (a notable problem for VCRs), and the lower-cost media. Western sources have cited counterfeiting as a principal concern of VCD users.
In Asia, the use of VCDs as carriers for karaoke music is very common.
VCD is popular among the Indian Film industry, many Indian movies being sold on VCD which allowed even poor families to afford them. However, because of Indian movies' increasing popularity, there are high demands for optional subtitles in other languages to be included with the movie along with "bonus" material like Hollywood.
In Burma, VCDs are the medium of an underground video network that largely stays beneath the sights of the military regime, although VCD trends are reported on by expatriate newspapers. Popular videos include Buddhist monks speaking out against the regime and comedy skits ruthlessly mocking military leaders. It is reported that even soldiers watch the VCDs in their barracks.
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 (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.
Due to relatively small storage capacity, feature-length films sold on VCD are usually divided into two or three discs and television series may come in a boxed set package with multiple discs. In both cases, most films run at roughly 60 minutes per VCD, before viewers are prompted to change discs. However, there are also VCD players that have built-in CD changers which provide a queue of several discs. Subtitles are found on many Asian VCDs but cannot be removed, unlike DVDs. The subtitles are embedded on the video during the encoding process. It's not uncommon to find a VCD with subtitles for two languages.
VCDs are often bilingual. Because they feature stereo audio, disc players have an option to play only the left or right audio channel. For example, ERA of Hong Kong's release of the animated film The Iron Giant features English on the left audio channel and Cantonese on the right. This is similar to selecting a language track on a DVD, except it's limited to 2 languages, due to there being only two audio channels (left and right).
VCDs also cost less than DVDs. A brand-new Hollywood blockbuster on VCD is typically half the price of its DVD counterpart, if not less.
VCD does have a few advantages over DVD-Video:
Video CDs are not popular in the US, Canada, Europe, Middle East & Northern parts of Africa, so its support is limited among mainstream software. Windows Media Player prior to version 9 and Quicktime player do not support playing VCD directly, though they can play the DAT files (stored under \MPEGAV for video and audio data) reliably. Windows Vista added native support of VCD like DVD-Video and can launch preferred application upon inserting.
|This page or section does not have any sources. You can help Wikipedia by finding sources, and adding them. Tagged since October 2007|
Since a DVD can store ten times as much information as a VCD, the quality of a VCD is not as high as that of a DVD, yet is ten times cheaper to make. The quality of the picture is about as good as a normal TV with a simple antenna.
VCD's were invented by Philips and Sony just like the CD, but then never became very popular in the Western world, which switched from VHS tapes directly to the DVD. However, in Asia and in other developing countries the VCD is popular, since a DVD player is also much more expensive than a VCD player.
A VCD movie is stored in the popular MPEG (.MPG) format, that is also often used to download movies from the internet. But if a VCD disk is put in a computer, there is a file with a .MPG after the name, and many other files. This is because the movie is actually in a file (or files) that has .DAT after the name. This file can be played with Windows Media Player (or any other player that can play a .MPG movie), one does not need special software because the file is actually just a .MPG movie with a .DAT end of the name instead of .MPG. There are also many programs that exist to make it possible to play a VCD on a PC.