Copyright Michael Karbo, Denmark, Europe.


  • Next chapter.
  • Previous chapter.


    Chapter 8. The MiniDisc

    The Compact Disc format was, as we have seen, developed jointly by the companies Sony and Philips back in the beginning of the 1980s. Ten years later the two companies went their separate ways, when each of them introduced a new digital music format designed for digital sound recording with the use of compression. Philip’s idea was to make a digital version of the hugely widespread analog Compact Cassette tape.

    Digital Compact Cassette (or DCC) became the name of this very advanced product, which, however, only had just less than five years on the market before production was brought to a standstill. There are probably not very many who remember DCC tape recorders today. Sony was much more successful with their small disks: MiniDisc.

    A little diskette

    A MiniDisc is a little, but rather advanced, disk of the so-called magneto-optic type. In the original version a MiniDisc can contain 74 minutes of music corresponding to the playing time of a normal music CD.

    Figure 40. A MiniDisc player is a very compact and delightful product.

    But while a normal CD-ROM contains about 700 MB data, there can only be 140 MB on a MiniDisc. But it can still contain double as much music as a CD. This can, of course, only be achieved by using data compression.

    Figure 41. A MiniDisc is 7 x 7 cm and is, therefore, smaller than a normal computer diskette.

    ATRAC compression in several modes

    A MiniDisc is based on a number of software techniques, which together are called ATRAC. This stands for Adaptive Transform Acoustic Coding, and is Sony’s system for sound compression. Sony’s objective was to squeeze a whole CD with 74 minutes of music onto a diskette with enough space for 140 MB data. This can be done with a bit rate of 292 kbps.

    Thjs compression is quite “mild”, as the amount of data is only reduced by a fifth and the sound quality is also splendid. Only very few will be able to hear much difference between an original CD and a copy on a MiniDisc.

    The newer MiniDisc recorders can work in two modes: LP2 and LP4, which quite simply means larger compressions.

     

    Mode

    Bit rate

    Time per disk

    Quality

    Normal

    292 Kbps

    74

    ****

    LP2

     132 Kbps

    160

    ***

    LP4

    66 Kbps

    320

    **

    Figure 42.A MiniDisc can work in three modes with different compressions and, thus, playing time per disk.

    LP2 mode has proved to be nearly identical with Normal mode. This is quite consistent with the mp3 format, where an encoding with 128 Kbps will for most give an acceptable quality.

    In the LP4 mode there is a further doubling of compression, and furthermore a common encoding of the two stereo channels (just like in the mp3 format). This gives a higher compression effect. The sound quality cannot be called hi-fi, but it is surprisingly good and is well suited to jogging or other sorts of playing back while in motion.

    Recording

    Music is recorded on MiniDiscs in two ways

  • Analogically.

  • Digitally (with an S/PDIF-interface).

    It is on the face of it easiest to, for example, use the headphone port on a CD player, for recording. It can be connected to the Mini­Disc’s microphone port with a cable, which comes with the MiniDisc (with a minijack at both ends). This will give an analog recording.

    The drawback is, that the CD’s digital sound track is first converted to analog sound, which is then converted back to digital sound. The more conversions the music is put through, the more inferior the quality will be.

    Figure 43. You can see here two superfluous conversions from digital to analog sound and back again.

    Digital connection

    If you want to give a MiniDisc the best conditions for making a high quality recording (whatever the mode), then you ought to use a fiber optic cable (TOSLink). The cable transfers data with the help of light – red light. It looks weird the first time you see it:

    Figure 44. The fiber optic TOSLink cable transfers data with the help of red light.

    The TOSLink cable transfers data directly and in digital form from, for example, an audio CD to a MiniDisc. This means, that it is pure digital data, which is compressed and stored in the MiniDisc and the quality is, therefore, optimal.

    The optic connection requires a corresponding optic port in the device you are going to record from. This is usually called Digital Audio Optical Out, as seen here:

    Figure 45. Two digital ports in a DVD player.

    Both the optic plug and the ports are protected with little plastic covers when they are not in use. There might be an optic port in your sound card, on a CD player and a DVD player.

    Many MiniDisc players are ”stupid” in the way that they only will accept a stereo signal of 44,1 kHz or 48 kHz with 16 bit resolution. This means that you can’t just transmit a surround signal via the optic cable and believe that this will give a wonderful recording. The recorder can’t understand this at all; the signal has to conform to the Mini­Disc.

    If you want to, for example, transmit mp3 files from a computer to a MiniDisc, then you ought to use the optic link; mp3 files have been compressed once already. To be able to record them on a MiniDisc they have to first be decompressed, and then compressed again in the MiniDisc. It’s not optimal, but the sound quality will be acceptable if the files are transmitted digitally – without further analog/digital conversions.

    So always use the optic cable rather than the normal analog when you record on a MiniDisc. If you would like intervals between the tracks (time codes), then record with a program like MiniDisc Center (see
    page 3).

    Figure 46. An optic cable (TOSlink), which can connect a sound card or a DVD/CD player to a MiniDisc player for direct digital transfer.

    Conclusion

    Sony’s MiniDisc was an excellent product. The players give a really good sound, and they don’t take much room. In fact, they ought to in my opinion, be built into many more stereo systems, car radios and even DVD players, than they are. For one reason or another, MiniDiscs have never really become widespread, which could have helped to reduce their cost. Today flash ram-based MP3 players have taken over the market.


  • Next chapter.
  • Previous chapter.


  • Book overview.