discs

Discs

MiniDiscs were introduced by Sony in 1992.

Originally available in 60 minute discs. Later expanded to match full-size Compact Discs in runtime; 74, and 80 minute lengths, when recorded in original SP format; ~292kbps encoding ATRAC.

For NetMD/MDLP format, introduced in September 2000. This extends run-time as follows:

  • LP2 being double: 120 min (2 hours), 148 min (1 hour, 24 min), 160 min (1 hour, 40 min), roughly halving SP encoding, ~132kbps
  • LP4 being quadruple: 240 min (4 hours), 296 min (4 hours ~56 min), and 320 min (5 hours, 30 min), roughly quartering SP encoding ~66kbps
Mode of Recorded Audio Data1) Track Mode (UTOC)Result when played on MDLP unitResult when played on non-MDLP unit
SP stereoSP stereoSP stereoSP stereo
SP monohalf-speed SP monohalf-speed SP mono
LP2silentSP stereo
LP4silenthalf-speed SP mono
SP monoSP stereodouble-speed SP monodouble-speed SP mono
SP monoSP monoSP mono
LP2silentdouble-speed SP mono
LP4silentSP mono
LP2SP stereosilentsilent
SP monosilentsilent
LP2LP2silent
LP4nonstop squealsilent
LP4SP stereosilentsilent
SP monosilentsilent
LP2double-speed LP4silent
LP4LP4silent

Hi-MD, introduced in January 2004, was a nearly complete revamp of the MD system.

The most significant change is the introduction of Hi-MD media, which includes a new 1GB blank in the existing MD form-factor and a reformatting of existing MD media that doubles its capacity to 305MB. In addition, several important and long wished-for Minidisc capabilities have been incorporated into Hi-MD equipment.

  • Hi-MD recorders can be used directly as USB connected data drives on any PC supporting USB storage devices (no additional drivers needed)
  • This allowed drag-n-drop of audio (and other) files directly onto the Hi-MD disc.
    • This includes PCM (WAV) as well as standard/Hi-MD ATRAC files; additional software is needed for 1st-generation Hi-MD hardware. 2nd-generation does not
  • This introduced several new, Hi-MD-specific modes: Hi-SP (256kbps) and Hi-LP (64kbps) via ATRAC3plus
Encoding ModeRecording capacity(1) Created by …
305MB Hi-MD
formatted Minidisc
1GB Hi-MD Mediarecording with
Hi-MD equipment
downloading from PC
to Hi-MD equipment
Linear PCM 1411kbps (1.4Mbps)28m1h 34mOyesXno
ATRAC3plus 256kbps “Hi-SP”2h 20m7h 55mOyesOyes
ATRAC3plus 64kbps “Hi-LP”10h 10m34hOyesOyes
ATRAC3plus 48kbps13h 30m45hXno Oyes
ATRAC3 132kbps “LP2”4h 50m16h 30mXno Oyes
ATRAC3 105kbps6h 10m20h 50mXno Oyes
ATRAC3 66kbps “LP4”9h 50m32h 50mXno Oyes
ATRAC 292kbps “SP”Not supported on Hi-MD media
Current MD formatExisting MD formatted into “Hi-MD”Hi-MD 1GB DiscMD-View
(from MD Discam)
Data Capacity177MB305MB1.0GB650MB
Magneto-Optical Recording MethodMagnetic Field ModulationMagnetic Field ModulationDomain Wall Displacement DetectionMagnetic Field Modulation on two layer medium (record layer and record assist layer)
Laser Wavelength (λ)780nm780nm780nm655nm
NA of Objective Lens0.450.450.450.52
Diameter64.8mm64.8mm64.8mm64.8mm
Thickness of Substrate1.2mm1.2mm1.2mm1.2mm (but with new substrate resin)
Tracking FormatGroove RecordingGroove RecordingGroove RecordingGroove Recording
AddressingWobbling Groove (ADIP)Wobbling Groove (ADIP)Wobbling Groove (ADIP)Interlaced Wobbling Groove (ADIP with 1 address per track)
Data ModulationEFM1-7RLL1-7RLL1-7RLL
Data DetectionBit by BitPRMLPRMLBit by Bit
Bit Length0.59μm0.44μm0.16μm0.34μm
Shortest Mark Length0.83μm0.58μm0.21μm
Track Pitch1.5μm1.5μm1.25μm0.95μm
Data Transfer Rate1.25Mbps @1.2m/s4.37Mbps @2.4m/s9.83Mbps @1.98m/s9.4Mbps

MD Data: 140MB

MD Data2: 650MB

Hi-MD: 1GB


MiniDisc varieties (non-exhaustive) MD vs CD size

MD vs CF and SD cards MD vs 3½" Floppy


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