Video-CD

VideoCD or VCD is a standard for storing video data on a compact disc to play it on special playback devices ( VCD players, CD -i players and most DVD players ) in connection with a TV or on personal computers. Video - CD files can be identified by the file extension. Dated

Technical details

The VCD standard was agreed in 1993 by a consortium of Japanese electronics manufacturer and recorded in the so-called White Book. He is one of the official CD formats that can carry the Compact Disc logo - in this case, Compact Disc digital video. He describes the storage of video data according to the MPEG -1 standard on a standard CD. The standard resolution is set for PAL 352 × 288 pixels at 25 frames per second for NTSC 352 × 240 pixels at 29.97 or 23.976 frames per second. The aspect ratio is 4:3. 16:9 is not provided. The sound is stereo. Joint stereo digital surround sound, multiple audio tracks or selectable subtitles are not possible on VCDs, mono sound must be implemented if required as in the audio CD by identical left and right tracks. The data is saved twice. The bitrate should be at a maximum of 1,151,929 bits / s for the image data, exactly 224,000 bit / s for stereo sound data ( in MP2 format ) and exactly 1.4112 million bit / s for the entire data. The latter corresponds to the bit rate of audio CDs; Thus, the maximum term is identical, and VCD players can use the same drive mechanism as normal CD player. Variable bit rates are not provided. On a standard-compliant Video CD playback software for a CD-i player must be saved because they come with no such. This software costs about one minutes duration.

Image quality

The picture quality is approximately equal to a VHS video, but is slightly worse than that of a high quality and recorded with good professional recording devices VHS tape. Although the VHS typical image and color noise is omitted, it ( " blocks " to form a ring around objects ) and jerky movements are on video CDs blurring, compression artifacts visible. The sound quality is much better than mono- VHS, but often worse than HiFi VHS. The picture quality varies depending on stimulus encoding software and their settings used, but can not exceed a certain maximum. This, and the maximum playback time of originally good 73 minutes ( well today 79 minutes when using a 700MB CD -R ), VCDs are suitable as a medium for feature films is limited.

Another disadvantage of the Video CD is the opposite of the TV Full resolution ( 576 visible lines in Europe, 480 in America ) reduced vertical resolution ( 288 or 240 visible lines ), ie every second grid line is " thrown away ", whereby the interlacing of the original signal and thus time resolution is lost. Many analog video formats, such as VHS, this property did not systemic.

For some years there is a non-standard VCD variant called MVCD, even KVCD, TVCD, AVCD or commonly called XVCD for DVD players. This provides, inter alia, by a modified quantization matrix increased playing time and some slightly better image quality, but is not affiliated with any DVD player and playable on pure video CD players do not work.

Dissemination

Before VCDs in Europe and America were common, they were already very popular in Asia; there also many VCD recorders were sold, with those CD - R discs can be played on VCD. Reasons were in relation to VHS much simpler and more robust mechanics, low prices for players and media, as well as the much lower compared to VHS tapes sensitivity to high humidity; particularly in Southeast Asia VHS tapes are often attacked by mildew. The low cost of VCD media and the non-existent copy protection could proliferate in this area commercially distributed illegal copies. This is probably the reason that this standard was never strongly supported by the industry in the United States. The subsequent availability of re-writable CD -RW and cheap CD recorders has led to a rapid proliferation of privately burned Video CD, especially since they can also be played back in most DVD players.

The extended standard and thus the successor is the SVCD (Super Video Compact Disc). It is based on the MPEG-2 compression and supports variable data rates. Thus, increased image quality compared to the VCD is achieved with its MPEG-1 compression, but at the cost of even lower runtime.

Due to the advent of DVD burners for the mass market, the VCD was increasingly replaced by the DVD for private recordings. This has most of the advantages of VCD for customers. Then there is the much better picture and sound quality as well as increased playing time.