Tagged: Compact Disc

Optical disc formats that are variants of the Compact Disc

Enhanced CD (1994 – )

An enhanced CD (or ECD) is a Compact Disc that contains both audio content playable on a standard CD audio player, and multimedia content playable on a computer CD-ROM.

Introduced in 1994, the idea behind enhanced CDs was to offer the music buyer some extra bonus features using space on the disc that was unfilled by the music. This might take the form of music videos (similar to the earlier idea of CD Video), interviews, wallpapers, pictures, lyrics, or links to an artists website.

Rather confusingly, there were three different ways on combining the different content on the disc. Prior to 1996, enhanced CDs were created in one of two ways. One was to have the multimedia content in the first track, but this meant that track 1 needed to be skipped when played in a standard CD audio player or else the multimedia track could cause an unpleasant noise to be heard. A subsequent solution was to have the multimedia content in the pre-gap before track 1 (rather like the way a CD-i Ready disc worked). Both of these methods were known as ‘mixed-mode’, combining Red Book Digital Audio and Yellow Book CD-ROM information in a single ‘session’ on the same disc.

To get around the problems of mixed-mode discs, Philips and Sony released the Blue Book standards in 1995, and worked with Apple, Microsoft and the Recording Industry Association of America (RIAA) to develop them. This new standard specified multisession technology that used two sessions on the disc, the first one containing audio tracks, and the second one containing data that is invisible to CD audio players. In 1996, most enhanced CDs used mixed-mode with the multimedia in the pre-gap, but by 1997 most were using Blue Book standards. The only downside to the newer multisession technology was that CD-ROM drives made before 1996 might not recognise them if they were not multisession capable.

Enhanced CDs can usually be recognised the official ‘Enhanced CD’ logo recommended by the RIAA. They may also have the CD EXTRA logo (previously known as CD Plus), which was trademarked by Sony for use on Blue Book discs.

Later technologies like DVD-Audio or DualDisc tried to perform the same function of offering the music album with bonus material such as videos, but later albums often came instead with the videos on a separate DVD-Video.

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CD-i Ready (1991 – 1998)

CD-i Ready was a hybrid optical disc format, combining audio tracks readable by any Compact Disc audio player, and multimedia or interactive elements readable on a CD-i (Compact Disc Interactive) player. It was introduced by Philips in 1991.

The audio tracks conform to Red Book Compact Disc Digital Audio standards, while the CD-i part conforms to Green Book standards, and could contain interviews, photos, biographies, games and more. The CD-i component is located in the ‘pre-gap’ area before track 1, which is skipped over by Compact Disc audio players.

The idea, like CD-i generally, was not a commercial success, and there appear to be fewer than 20 titles released as CD-i Ready discs.

The ideas behind the hybrid CD-i Ready discs were used in later types of hybrid audio/data discs such as the Enhanced CD that contained content which could be read on a standard computer CD-ROM drive rather than requiring a dedicated CD-i player.

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Compact LaserDisc (1986)

Compact LaserDiscs were 12-inch LaserDiscs that combined a complete music album (as would be found on the equivalent Compact Disc) in digital audio, along with music videos for some of the tracks. When played as an audio album, the screen would show a picture of the sleeve and the name of the track.

Around just seven titles were released by Pioneer Artists in 1986, for distribution in the US.

The name is a bit of a misnomer as they were anything but compact, but it was meant to emphasise that these were essentially a Compact Disc album with added videos. They are very similar in concept to CD Video, except able to hold an entire music album.

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Holographic Compact Disc (1991 – 1996)

Holographic Compact Discs are standard Compact Discs with a holographic design incorporated into them. These appear on both sides of the disc, and the playing area is kept within the 3-inches of a mini CD single, limiting playing time. The playable part of the disc conforms to Red Book standards.

A handful of singles and interview discs were released, mostly between 1991 and 1993. Almost all releases were mastered by Nimbus and Applied Holographics.

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XRCD (1995 – )

XRCD (eXtended Resolution Compact Disc) was introduced by JVC in 1995. XRCD discs conform to Red Book standards and will play on any Compact Disc player, but claim to use much higher quality mastering and manufacturing processes to produce a sound as close as possible to the original master tape.

Subsequent versions of XRCD are called XRCD2 and XRCD24.

All versions of XRCD disc are encoded at 16 bits; the 24 in XRCD24 refers to the use of 24 bit encoding when digitising the original analogue source (XRCD and XRCD2 used 20 bit encoding of the original source).

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CD-i Digital Video (1993 – 1994)

CD-i Digital Video was a short-lived video disc format introduced by Philips in 1993 that was designed to be played in CD-i players equipped with an optional Digital Video Cartridge. This expansion unit contained a 32 bit RISC processor and 1 MB of RAM to provide MPEG-1 decoding.

CD-i Digital Video followed the Green Book standard for CD-i discs, making it incompatible with the Video CD format introduced shortly afterwards that followed the White Book standard. However, whilst Video CD players could not play CD-i Digital Video, CD-i players with the optional Digital Video Cartridge could play both formats. Some other CD-i discs such as games also made use of the Digital Video Cartridge to play video.

One of the two differences between the formats was the resolution, that was slightly higher on CD-i Digital Video (384×288 instead of 352×288 for Video CD). When a Video CD is played on a CD-i player, slightly larger pixels are displayed to fill the screen.

Only around 20 movies were released on CD-i Digital Video before Philips switched to Video CD for distributing movies in 1994.

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High Definition Compatible Digital (HDCD) (1995 – )

High Definition Compatible Digital (usually known as HDCD) is a Compact Disc based music format that uses a proprietary encoding system to provide increased dynamic range over standard Compact Discs by encoding 20-bits worth of data in the 16-bit digital audio signal.

It was originally developed by Pacific Microsonics, and the first HDCD releases were in 1995. The technology was subsequently purchased by Microsoft in 2000, and although the official HDCD website was taken down in 2005, there continue to be small numbers of HDCD releases.

HDCD discs can be played in standard Compact Disc players (although there are some claims of distortion), but to take advantage of the claimed improvements in quality requires a HDCD-compatible player, or later versions of Windows Media Player on PCs.

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Mini CD-R / CD-RW (1990s – )

Mini CD-R (CD-Recordable) and Mini CD-RW (CD-Rewritable) are 8cm versions of CD-R/CD-RW. They can hold anything from 156 MB (18 minutes of music) to 210 MB (24 minutes of music).

They can be written to in spindle-based or tray-loading CD-R / CD-RW burners (and read in spindle-based or tray-loading Compact Disc players) but there were also some devices that were specifically designed around the Mini CD-R/CD-RW.

One of these was a number of models in the Sony Mavica line of digital cameras. The first of these was the MVC-CD1000 released in 2000, which could record to Mini CD-Rs. Later models in the line (the last of which was released in 2003) could use either Mini CD-R or Mini CD-RW.

There was also a portable Mini CD-R burner called the Imation RipGo! that was introduced in 2001. This could burn MP3 files to disc, and also play them back. Sony also introduced a Mini CD burner (called the PhotoVault), allowing pictures to be saved from a Memory Stick, USB flash drive, or camera with a USB connection.

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VinylDisc (2007 – )

VinylDisc (also known as vinyl CD) is a hybrid Compact Disc and vinyl phonograph record, developed in Germany by Optical Media Production and first released in 2007.

The CD side is a standard full-length CD, and the vinyl side is a 33⅓ rpm record that can play up to 3.5 minutes of audio on a regular phonograph, although the small size means the vinyl side won’t play on automatic or semi-automatic turntables.

Around 50 or so singles and albums have been released on VinylDisc.

VinylDiscs come with a small centre spindle adapter that can is removed to play the disc in a Compact Disc player.

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CD-BGM (1989 – late 2000s)

Audio CDi (front)CD-BGM (CD-BackGround Music) was an audio format for background music systems, introduced by Philips in collaboration with several companies in the background music business in 1989.

Philips used a compression algorithm that was being developed for CD-i, ADPCM (Adaptive Delta Pulse Code Modulation). Audio is mono, and is stored at Level A – C compression, allowing up to 4,8 or 16 hours of music.

Because of Philips’ work on the CD-i at the time, all CD-BGM discs are compatible with the CD-i system even though the CD-i system wasn’t introduced until 1991, and can be played in CD-i players. CD-BGM is often referred as audio-only CD-i, and meets the Green Book specifications for CD-i.

It was not the intention for CD-BGM discs to be played on domestic CD-i players, and dedicated players were offered by companies working in the background music industry. Usually, these used a caddy system similar to early CD-ROMs, but much more secure as the discs were often used in unfavourable environments such as restaurants and planes. The discs were usually part of a subscription, and were returned to the supplier to get new ones.