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VCD Digital Video

The VideoCD format was created to satisfy the demands of both the entertainment and information publishing worlds. The aim was to provide a format capable of delivering their content on an interactive medium that was inexpensive to replicate, supported full-screen, full-motion video, and which worked on a wide range of different platforms PCs, televisions, and games or multimedia platforms.

It was in mid-1993 that Philips, Sony, Matsushita and JVC agreed the VideoCD specifications, later referred to as the “White Book”. The White Book parameters build upon the tight definitions described in the Red (CD-DA) and Yellow Book (CD-ROM) standards and introduce the flexibility to allow for the insertion of copyright and bibliographic information, abstract data, and computer programs to enhance interactive control during playback.

At the time of its release, VCD required expensive dedicated MPEG decoding hardware. Subsequent developments in PC CPU technology altered things dramatically, thereby opening up VCD to mass consumer markets. The format became hugely popular in Asia, where most households didn’t already have VCRs. Since the mid-1990s, almost all Hong Kong films have been available on VCD and by the end of the millennium it was estimated that more than 2 million VCD players annually were reportedly being produced in China alone. Whilst its popularity has waned with the advent of DVD, the market for illegal bootlegged VCDs has kept the format alive in the east. The format never caught on in the west and remains practically unheard of in North America and Europe.

VCD uses CD-ROM XA Mode 2 to record the first track on the disc (Track 1), which contains the ISO 9660 file structure and Information Area. The ISO file system can also embed Joliet extensions to provide support for Windows long file names. The 1993 VCD 1.1 standard is fundamentally “linear” inasmuch as it defines a format that is generally run from starts to the end. VCD 1.1 does support the notion of selectable tracks, but it was not until the 1995 VCD 2.0 version that full interactivity via a remote control was supported. This increased the format’s popularity dramatically, making it appealing for a wide range of multimedia applications such as training, sales presentations and interactive entertainment products. VCD 2.0 allows up to 98 other tracks, each of which can be indexed at up to 99 points. Each AV track can contain play items which can be video, audio, or still images. Basically, the format can be thought of as an Audio CD with the addition of moving and/or still pictures and on-screen navigational control. The standard maintains backwards compatibility, so that version 1.1 VCDs work in version 2.0 players.

The following table summarises the key characteristics of the PAL, NTSC and rarely used NTSC Film variants of the VCD standard:

PAL NTSC NTSC Film
Resolution 352×288 352×240 352×240
Frame rate 

(frames/second)

 25 29.97 23.976
Video bitrate 

(Kbit/second)

 1150 

MPEG-1

 1150 

MPEG-1

 1150 

MPEG-1
Audio 44.1kHz stereo, encoded in MPEG-1 Level 2 format, at a bitrate of 224kbits/second
Total bitrate 1394.40kbits/second

Most VCD players that play PAL video resolution on a NTSC monitor correctly will cut 24 lines of resolution from the top and bottom of a PAL image. This conversion problem does not exist when a VCR is viewed on a PC monitor and indeed, most modern day TVs and DVD players are multisync and able to play both NTSC & PAL format.

A dedicated VCD player is designed to play only VCDs and is not a general purpose multimedia machine. It can be thought of as a VCR for compact discs. A VCD has the capacity to hold up to 74/80 minutes (on 650MB/700MB media respectively) of full-motion video and stereo sound. MPEG-1 compression technology (ISO standard IEC 11172) is used for encoding, providing video quality equivalent to VHS VCR tape and near CD-DA audio quality. The degree of standardisation is such that a VCD can be played on almost all standalone DVD Players, on games platforms – such as Playstation, Sega and Dreamcast – provided they’re equipped with the necessary add-ons and on DVD-ROM or CD-ROM drives with the help of a software based decoder/player. However, some DVD Players will not handle VCDs on CD-R media (that is, home made discs). Experience has shown that most Sony and Pioneer models are least likely to have problems, whilst DVD Players from other manufacturers may fail to recognise VCDs burned to CD-R media.

VCD was the first moderately successful digital video standard and the forerunner to the DVD format that was to eventually dominate the digital video consumer market. However, fuelled by the increasing availability of affordable CD Rewritable drives and their ever cheaper media, other formats were to emerge – some official “standards”, others not – that provided consumers with alternative solutions for distributing movie content in formats that offered the combination of quality and low cost.

SuperVCD – effectively a VCD that uses MPEG-2 encoding rather than MPEG-1 – was the next such format to emerge.

 

Filed Under: Digital Video

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