Specifications

CD-i FAQ 2000 Edition Revised February 21, 2001
Latest version and more CD-i info: http://www.icdia.org
32
5.7 What is Video-CD?
A Video-CD is a compact disc with up to 75 minutes of VHS quality video with accompanying
sound in CD quality. Audio and video are coded according to the MPEG-1 standard and the disc
layout is based on the CD-i Bridge specification to allow for the playback on a variety of
plackback devices like CD-i players and dedicated Video-CD players. The first version of the
Video-CD spec was still called Karaoke-CD (see: 5.8 What is Karaoke-CD?) and was set up by
Philips and JVC in 1993. Soon after followed the 1.1 spec, in which the name of the system was
changed into Video-CD and the spec publishers were joined by Sony and Matsushita. Some
years later, the 2.0 version added the ability to store still pictures on the disc and even allows for
limited interactivity in the form of menu screens and selection items.
Video-CD became very popular mainly in Asia, as some 40 million Video-CD compatible players
were sold by the beginning of 2000. Outside of Asia, Video-CD was mainly used as a prototype
tool or as a cheap way to produce DVD-Video compatible discs. Although Video-CD compatibility
is not required for DVD-Video players, it is very likely that Video-CD playback functionality is
included since every DVD-Video player must be able to decode MPEG-1 as well.
For more information about Video-CD, the difference between Digital Video on CD-i and Video-
CD, the various Video-CD versions, the various Video-CD applications for CD-i and other
questions, please refer to section 6 of this FAQ: Video-CD on CD-i.
5.8 What is Karaoke-CD?
Karaoke-CD is the old name of the Video-CD standard. It dates back to 1993 when the standard
was set up by Philips and JVC and the support of Sony and Matsushita was not yet there (they
joined some time later when the name was changed into Video-CD). Karaoke-CD was -as its
name already shows- mainly intented for karaoke applications in Japan. The system uses MPEG-
1 audio and video, and is based on the CD-i Bridge specification. Therefore, Karaoke-CD is
completely compatible with CD-i players among others.
5.9 What is Photo-CD?
The Photo-CD system was defined jointly by Philips and Kodak in 1991. The system allows for
the storage of very high quality photographic images on a compact disc. The system is based on
the CD-i Bridge specification to allow for the playback of Photo-CD discs on CD-i players, Photo-
CD players (an overview of all Photo-CD players is available in the Related Technologies section
at www.icdia.org) and other systems.
Photo-CD was introduced as a complete consumer service product. Consumers were able to
request for a Photo-CD when they brought their 35mm film to a Kodak photo-finisher for
development. The resulted disc contained all of the photos in a variety of image resolution
qualities. The disc could be returned to the photo-finisher to add more photo's, up to a total of
slightly over 100 pictures. For this, the multi session feature was added to the CD-Recordable
definition in the Orange Book.
The pictures on a Photo-CD a coded according to a Kodak-developed compression technique
called Photo YCC. This algorithm makes use of the fact that the human eye is far less sensible
for color differences than for changes in brightness in a picture. This reduces the size of a
scanned picture from 18 MB to 3 to 6 MB per 'Image Pack'. Each picture is stored in an Image
Pack, which containes one picture in 5 resolutions: Base/16 (192 x 128), Base/4 (384 x 256),
Base (768 x 512), 4Base (1536 x 1024) and 16Base (3072 x 2048). These different resolutions
can be used for a variety of purposes: the smallest ones can be used to produce a thumbnail
overview on screen, the middle resolution can be used to show the picture in high quality on a TV
screen, the 4Base resolution is used to zoom in on a particular area of a picture and the highest
resolution can be used to make photographic quality prints. The latter one makes Photo-CD an
excellent and durable storage medium.