Video CD
What is a Video CD?

Video CDs are defined in the White Book. They contain MPEG-1 audio and video for mainly linear video applications. Video CDs are multi-track, CD-i Bridge discs designed also to play on CD-i players.

The Video CD specification was written by Philips, Sony, Matsushita and JVC. It is a generic format which (like audio CD) is hardware independent. The original version was for Karaoke CD as a replacement for the ageing VHD video disc systems used in many Karaoke bars in Japan.

Special purpose designed Video CD players have been developed in the Far East as enhanced CD players with Video CD capability. Generally they offer a lower cost solution for playing Video CDs, as well as audio CDs, but not other CD-ROM/CD-i discs.

Despite the introduction of DVD-Video, Video CD has been given a new lease of life (particularly in China) with the introduction of newer versions including HQ-VCD.

Please note that Video CD (VCD) and CD Video (CDV) are not the same thing. the latter format is a combination of CD audio and analogue video.

Video CD Features
The main features of the Video CD specification are listed below.

Playing time: 74 minutes
Video: MPEG-1 encoded video
Resolution: 352 x 240 at 30 fps (NTSC) or 352 x 280 at 25 fps (PAL/SECAM)
Audio: MPEG-1 stereo and optional CD audio tracks
Stills: MPEG-1 at up to 720 x 480/576 (can be used for menus)
Interaction: Menus to select entry point
Playlists for predetermined video/still/audio sequences
Fast forward and reverse
Subtitles: Closed captions
Entry points: Up to 98 entry points per track (500 total per disc).

Video CD discs also contain a CD-i program so they will play on CD-i players.

Video CD Tracks
White Book Video CDs are characterised by the use of multiple Tracks.

Track 1 contains the following data:

• CD-i application program.
  
• Track information for Karaoke or music videos (optional).
  
• Entry point addresses
  
• Playlists
  
• MPEG stills.

Tracks 2 upwards are used for the MPEG video data (optionally followed by audio tracks) files which also can contain the scan table information and closed caption data in the user data area. A Video CD disc must therefore contain at least two tracks.

Video CD Directories and Files

Most files on a Video CD disc have predefined filenames and are located in specific directories as shown below.

Directory Files Comments
VCD INFO.VCD
ENTRIES.VCD
PSD.VCD
LOT.VCD Album and disc identification
Entry point list for up to 500 entries
Optional Play Sequence Descriptor
Optional List ID Offset file
MPEGAV AVSEQnn.DAT MPEG files (one per track)
CDDA AUDIOnn.DAT CD Audio files (one per track)
SEGMENT ITEMnnn.DAT Segment play items (one per segment)
KARAOKE KARINFO.xxx Optional Karaoke information files
EXT PSD_X.VCD
LOT_X.VCD
SCANDATA.DAT
CAPTnn.DAT Optional extended version of PSD.VCD
Optional extended version of LOT.VCD
Optional list of I-frame addresses
Optional Closed Caption data (one per track)
CDI (undefined) CD-i program and data files

Super Video CD (SVCD)

Philips has recently released the tentative specifications for this new version of Video CD called SVCD. This format includes many of the features of DVD-Video but without the long playing time. The following table compares SVCD with Video CD ver 2.0.

Video CD v 2.0 SVCD

Playing time: 74 minutes 35 to 70 mins+
Data rate: 150 kBps 300 kBps
Video: MPEG-1
1.15 Mbps CBR MPEG-2
2.6 Mbps average VBR
Resolution: 352 x 240 (NTSC)
352 x 280 (PAL/SECAM) 480 x 480 (NTSC)
480 x 576 (PAL/SECAM)
Audio: MPEG-1 stereo CBR
optional CD audio tracks 2 streams MPEG-1 stereo VBR
optional 5.1 channel
Stills: MPEG-1 MPEG-2
Interaction: Menus, Playlists,
Fast forward/reverse More interactivity
Subtitles: Closed captions Overlay graphics
(4 selectable channels)
Entry points: Up to 98 per track
(500 total per disc).

Super VCD allows a full length movie to be stored on two or three discs. Multi-disc players can give near-seamless, uninterrupted playback of movies using this format. The use of MPEG-2 VBR (variable bit rate) video encoding, as used for DVD-Video, gives improved quality without an unacceptable reduction in playing time.

- posted by J @ 6:24 AM