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Super Video CD

A digital format for storing video on standard compact discs.
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Super Video CD (Super Video Compact Disc or SVCD) is a digital format for storing video on standard compact discs. SVCD was intended as a successor to Video CD and an alternative to DVD-Video and falls somewhere between both in terms of technical capability and picture quality.

Structure

Similar to VCDs, SVCDs comply with the CD-i Bridge format and are authored (or "burned") using the CD-ROM XA format. The first track is in CD-ROM XA Mode 2, Form 1, and contains metadata about the disc. The other tracks are in Mode 2, Form 2, and contain audio and video multiplexed in a MPEG program stream (MPEG-PS) container. This allows roughly 800 megabytes of data to be stored on one 80 minute CD (versus 700 megabytes when using Mode 1). One CD can hold up to 35 minutes of full quality SVCD-format video and audio.

Video

  • Compression: MPEG-2
  • Resolution: 2/3 D1
    • NTSC: 480x480
    • PAL/SECAM: 480x576
  • Aspect Ratio: 4:3
  • Framerate:
    • NTSC: 29.97 frames per second
    • PAL/SECAM: 25 frames per second
  • Bit rate: Up to 2.6 megabits per second
    • Rate Control: Constant or variable bit rate

Because of its 480x480 resolution, SVCD picture quality is more than double that of VCD. On the downside, this increase in picture resolution sacrifices video length capacity by over 50%. Because of this, titles released on SVCD had to come on twice the number of discs.

Unlike other CD-based formats, such as China Video Disc and Video CD, Super Video CD video is incompatible with both the DVD-Video and Blu-ray standards due to a conflict in resolution. However, many DVD and Blu-ray players will playback SVCD resolution video from a DVD or Blu-ray disc anyway.

Interlaced video is supported for SVCD video, though not required. 23.976 frames per second video are supported by the use of interlacing and 3:2 pulldown.

The combined audio and video bit rates should not exceed 2.7 Mbps. This data rate was chosen, in part, to ensure compatibility with slower and less expensive "2 × speed" CD drives.

Audio

  • Compression: MPEG-1 Audio Layer II
  • Frequency: 44,100 hertz (44.1 kHz)
  • Output: Monaural, dual-channel, stereo, and multichannel support up to 5.1 output.
  • Bit rate: from 32 to 384 kilobits per second, inclusive
    • Rate Control: Constant or Variable bit rate

As with most compact disc-based video formats, SVCD audio is incompatible with the DVD-Video standard due to the difference in frequency; DVDs require 48 kHz, whereas SVCDs use 44.1 kHz.

SVCDs may have two separate stereo, or four mono audio tracks (for commentary or additional languages).

Audio may have up to 6 channels (in a 5.1 arrangement) using the MPEG Multichannel surround sound format, although space constraints and inconsistent hardware support make it impractical, and very uncommon.

Variable bit rate encoding, while not supported by the MPEG-1 Audio Layer II standard, is part of the SVCD specification. However, variable bit rate audio is not consistently supported by standalone players, and thus the format is rarely used.

Additional features

The SVCD standard supports several other features, including interactive menus, hyperlinks, karaoke lyric highlighting, four selectable overlay graphic subtitle streams, chapters, playlists, and DVD-quality still images/slide shows, along with audio, with a resolution of 704x480 (NTSC) or 704x576 (PAL/SECAM).

Playback issues

Playback of SVCD titles is impaired when played on most DVD players, causing dropped frames, choppy video playback, or skipping of sound. This is due to the unfortunately chosen two-thirds video ratio in the SVCD format specifications, which doesn't align well with the other more common video formats VCD and DVD. Most DVD players support the video formats VCD, SVCD, and DVD (with horizontal resolutions of 352, 480, and 720 pixels respectively) but the best resolution usually dictates the design of all the electronics components, most notably the low pass filter. With only one analog low pass filter optimized for one video format (usually DVD 720), the other two video formats will suffer from aliasing. The SVCD format is especially prone to "foldover" because the 480p format doesn't fit well over a 720p output. The aliasing artifacts that result from this bad fit are usually buried in noise from other sources, such as camera, quantization, and MPEG artifacts.

Key Terms

dvd
dvd video
form
khz
mode
output
resolution
super video cd
svcd
video cd

Additional Resources

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Acronymn

SVCD

Synonymns

Super Video CD
Super Video Compact Disc
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