The logical format of those CDs is described as a two channel sixteen bit PCM encoding at a 44.1 kilo Hertz sampling rate per channel.

The exact sampling rate of around forty four kilo Hertz was actually inherited from a basic method of converting digital audio into an analog video signal for storage on U-matic video tape, which was the most affordable way to transfer data at the time the CD specification was being developed for a music recording use.

But before Compact Discs were used, a different medium was used for audio recording. I know less and less people remember that but compact cassettes were very popular before the Compact Disc came in the market. Cassette being a French word meaning little box. It was actually the most common format used for music between the seventies and the nineties, especially as soon as portable pocket recorders and hi-fi players were introduced in the market. But although the tapes were quite durable, those players needed a lot of attention and care to be able to work properly.

Interestingly, vinyl record sales remained high for a long time before compact cassettes took over the market of singles.

The compact cassette also called tape is simply a magnetic tape which was originally used for dictation and not for music recording. All those compact cassettes included a write protection mechanism to prevent re-recording and accidental erasure.

It was an amazing step forward at the time of its launch and was much better than the first medium developed.

Those compact audio cassettes were first brought to the market by Philips in Europe and the United States at the beginning of the sixties with the aim of audio storage, with the mass production of those tapes starting as soon as nineteen sixty four.

Compact cassette duplication, replication and packaging was used like we use today CDs and DVDs for DVD packaging, CD duplication or replication. But obviously, Compact discs and DVDs can store much more data or music than the compact cassettes.

But in many markets in the western countries, the sales of tapes declined a lot at the beginning of the nineties because of the success met by the compact discs.