Super Video CD
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Super Video CD (Super Video Compact Disc or SVCD) is a format used for storing video on standard compact discs. SVCD falls between Video CD and DVD in terms of technical capability and picture quality.
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[edit] Technical specifications
SVCD has two-thirds the resolution of DVD, and over 2.7 times the resolution of VCD. Video is stored at 480x480 pixels for NTSC, and 480x576 pixels for PAL and SECAM. One CD-R disc can hold up to 60 minutes of SVCD-format video at a picture quality roughly comparable to Laserdisc. It is possible to fit nearly arbitrary amounts of SVCD video onto one CD-R, though one must lower the video bitrate, and therefore quality, in order to accommodate very long videos. It is usually difficult to fit much more than 100 minutes of video onto one SVCD without incurring significant quality loss.
Video is encoded as MPEG-2, and may have a variable bitrate up to 2.6 megabits per second. The lower bound for bit rate is not specified in the standard, though hardware compatibility on most SVCD and DVD players effectively limits it to between 300 and 600 kilobits per second. Audio is stored in MP2 constant bit rate format at a bit rate between 32 and 384 kilobits per second [citation needed].
The SVCD standard supports several other features, including menus, hyperlinks, karaoke lyric highlighting, overlay subtitles, and DVD-quality slide shows with resolution up to 704x480 (NTSC) or 704x576 (PAL). SVCDs may have two separate stereo audio tracks (for commentary or additional languages); audio may have up to 8 channels (in a 7.1 arrangement) using the MPEG Multichannel surround sound format, though space constraints and poor hardware support make it somewhat impractical.
Presentation of SVCD titles on most players is marred by an unfortunate violation of sampling theory almost built into the spec. The "2/3" choice for resolution is rarely consistently implemented end to end through the full player electronics. Because a DVD player might include provisions for various VCD, SVCD, and DVD horizontal resolutions (360, 480, 540 or 720) and only one analog low pass filter is provided, 2 out of the 3 formats will suffer aliasing when presented on the screen. Usually, the best resolution, DVD 720 dictates filter design, with SVCD display suffering from "foldover". While displays should follow correct theory, the objectionable aliasing artifacts that result are usually buried in noise from other sources, such as camera, quantization, and MPEG artifacts.
[edit] History of development
Super Video CD was originally developed by the government-backed China Recording Standards Committee, under direction from the Chinese Ministry of Information Industry, as an enhancement to the Video CD format. One of the motivating factors in its development was the need for an alternative to the DVD format that would not be restricted by technology royalties. The Chinese government was concerned that the DVD format was too tightly controlled by foreign companies, and that a significant opportunity existed for the development of a domestic format that could deliver comparable quality without the restrictions of DVD. It was also hoped that SVCD's development would help to drive down the cost of consumer DVD players and DVD licensing fees in China.
SVCD started as one of three independent efforts to solve these problems. The other two were China Video Disc (CVD), developed by C-Cube Microsystems, and High-Quality Video CD (HQ-VCD), developed by the Video CD Consortium, consisting of Philips, Sony, Matsushita and JVC, that created the original Video CD specification. CVD was first out of the gate, and had completed its specification before the other two had even reached a draft stage. The Ministry of Information and Video CD Consortium agreed to join forces, incorporating the features of HQ-VCD under a unified SVCD format, but by the time their specification was ready in July 1998, CVD had already been adopted by major manufacturers of VCD players. In order to maintain compatibility, CVD was also brought under the unified SVCD format, resulting in the Chaoji Video CD specification in November 1998. Chaoji Video CD, or Chaoji VCD, is roughly synonymous with Super VCD. A Super VCD player must be able to play a variety of formats, including SVCD, CVD, VCD 2.0, VCD 1.1 and CD-DA discs.
SVCD is under consideration for IEC standardization, so SVCD will likely become recognized internationally as a standard CD format, just as the Compact Disc and Video CD formats already are. Philips has already added an SVCD logo to its canon of official Compact Disc logos. SVCD titles are available commercially in China, Hong Kong, Taiwan, and several other Asian countries; whether the SVCD standard will enjoy commercial success outside of Asia remains to be seen, however. In the Western world, the format is more commonly used to store home videos or movies copied from DVD and Laserdisc.
[edit] See also
- DVD
- Video CD
- China Video Disc
- miniDVD - DVD video on a CD
[edit] External links
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| Magnetic tape |
VERA (1952) - 2 inch Quadruplex videotape (1956) - 1 inch type A videotape (1965) - U-matic (1969) - Video Cassette Recording (1972) - V-Cord (1974) - VX (aka "The Great Time Machine") (1974) - Betamax (1975) - 1 inch type B videotape (1976) - 1 inch type C videotape (1976) - VHS (1976) - Video 2000 (1979) - VHS-C (1982) - M (1982) - Betacam (1982) - Video8 (1985) - MII (1986) - D1 (1986) - S-VHS (1987) - D2 (1988) - Hi8 (1989) - D3 (1991) - D5 (1994) - Digital-S (D9) (199?) - S-VHS-C (1987) - W-VHS (1992) - DV (1995) - Betamax HDCAM (1997) - D-VHS (1998) - Digital8 (1999) - HDV (2003) |
| Optical discs |
Laserdisc (1978) - Laserfilm (1984) - CD Video - VCD (1993) - DVD (1996) - MiniDVD - CVD (1998) - SVCD (1998) - FMD (2000) - EVD (2003) - FVD (2005) - UMD (2005) - HD DVD (2006) - Blu-ray Disc (BD) (2006) - DMD (2006?) - AVCHD (2006) - Tapestry Media (2007)- HVD (TBA) - Protein-coated disc (TBA) - Two-Photon 3-D (TBA) |
| Grooved Videodiscs |
SelectaVision (1981) - VHD (1983) |
