CD-i Related Technologies: CD-BackGround Music (CD-BGM)
In the mid 80s, Philips wanted to use the compact disc format for their popular background music business, which was until then based on professional long-running tape systems. The only problem they were facing was the limited playing time of a compact disc: up to 75 minutes. Therefore, they decided to use a compression algorithm that was used in CD-i, which was then under development, namely ADPCM (Adaptive Delta Pulse Code Modulation), at level B in mono. This would allow for the discs to contain 8 simultaneous tracks of music data on the disc, enabling for 8 x 75 minutes = over 8 hours of music. The music was sampled at 37.8 KHz, and stored in 4-bit differential sample blocks. For the system to become a success, Philips teamed up with several other companies in the background music business, to set CD-BGM (Compact Disc BackGround Music) as a universally defined standard. Among them were Sanyo en Shinano-Kenshi (now better known from its Plextor brand). They decided upon all specifications, and as a result all CD-BGM discs are playable in all CD-BGM players.
The CD-i Application
It was in the same period that Philips was setting the standards for the CD-i system. All supporters of the CD-BGM format decided to include the presence of a CD-i application on the disc as a mandatory requirement of the specification, just to make sure that the CD-BGM discs would be playable on the new CD-i system if that market would evatually be booming. It was clear from the beginning that Philips put a lot more energy in the design and the features of the CD-i application than others. The CD-i application on the first CD-BGM discs that were released by other companies devided the TV screen in two parts, one saying 'start', the other saying 'stop'. Clicking start would begin the playback of all songs on the disc in sequential order. Ironically, these were the first "CD-i" discs ever produced. Philips, on the other hand, used a far more advanced CD-i application on their discs. It was developped by TeleCity CD-I in Hasselt, Belgium, which later became PIMC. This company also produced the first batch of Philips' CD-BGM titles (later this was taken over by Codim Interactive Media of Eindhoven, The Netherlands). The CD-i application displayed a list of all song titles that were present on the disc. The user could point a music note at a song name and click the action button to play the song. Besides this, there were 'play', 'stop', 'random' and 'eject' buttons. Strangely enough, the disc contained more information besides just the song title that could be viewed in the CD-i application. If you take a look at a Philips CD-BGM disc (using for example a professional CD-i player equiped to a terminal or the CD-i Filesystem Driver for Windows), you'll find text files containing the names of the songwriters for all titles and their playing time. These were probably required on the disc for copyright-legal reasons. In the end, Philips had produced thousands of CD-BGM titles which could be rented by companies and organisations until they sold their background music division in the late 90s. All of these discs contained the advanced CD-i application, but none of them were ever actually intented for usage on a CD-i player.
As stated before, the CD-BGM discs were never actually meant to be played back on a CD-i player, although all of them could! Instead, the participating companies offered dedicated CD-BackGround Music players. These players usually consisted of a profesional CD loading mechanism (based on the old 'Sony-cartridge' for CD-ROM drives) enabling it to run for hours, and an integrated amplifier, so that the store's speaker system could immediately be connected to the player. Next to CD-BGM discs with over 8 hours of music, the players were also capable of playing normal CD-Audio discs in stereo. One of the most populair CD-BGM players was the BMS3000 from Philips (see picture), which was actually build by Shinano-Kenshi. This company currenly still ships CD-BGM players in the East using its Plextor brand name. They have a whole range of models, including players with a 5 disc changers allowing for over 40 hours of continuous music. Please have a look at their website for more information.