VCD:

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 modern DVD-Video players, personal computers, and some video game consoles.

Technical specifications

Video

Overall picture quality is intended to be comparable to VHS video.^[3] Poorly compressed VCD video can sometimes be lower quality than VHS video, but VCD exhibits block artifacts rather than analog noise, 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, which must use 3:2 pulldown.

Audio

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.

Other information

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).

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. 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

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

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.^[4] KVCDs of commercial films are commonly distributed as disc images on peer-to-peer networks.^{[citation needed]}

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.

Adoption

While never gaining a foothold in the United States^[5] commercial VCDs are common in Europe,^[6] and very popular throughout Asia^[7] (except Japan), with 8 million vcd players sold in China in 1997 alone,^[8] and more than half of all Chinese households owning at least one vcd player by 2005.^[9]

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.^[5] Ease of duplication and the negligible cost of the media gave rise to widespread unauthorized copying in these areas.^[10] ^[11] ^[12]

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 addition many early DVD players could not read recordable (CD-R) media, ^[13] and this limited the compatibility of home-made VCDs. Almost every modern stand-alone DVD-Video player can play VCDs burned on recordable media.

VCD is popular among the Bollywood industry, many Indian movies being sold on VCD(along with DVDs) which allowed even poor families to afford. However, because of Bollywood's rapidly increasing popularity, there are high demands for optional subtitles in other languages to be included with the movie along with "bonus" material like its competitor, Hollywood, this is causing Bollywood to depend more strictly on DVD. They are also available in certain ethnic communities^[6] and several commercial web sites (although quality and authenticity may sometimes be questionable). These VCDs are often produced and sold in Asian countries such as China, Taiwan, Hong Kong, Singapore, Malaysia, Thailand, 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, 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.

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, and unlike DVDs, cannot be removed.

VCD's growth has slowed in some areas (where it was formerly very popular) due to the wide adoption of DVD-Video, which offers most of the same advantages, as well as better picture quality^[14] (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, Russia and Africa as a low-cost alternative to DVD. As of 2004, the worldwide popularity of VCD is actually increasing.^[15] ^[16]

VCD

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