Audio MiniDiscs
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 (2 hour, 28 min), 160 min (2 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, 20 min), roughly quartering SP encoding ~66kbps
Mode of Recorded Audio Data1) | Track Mode (UTOC) | Result when played on MDLP unit | Result when played on non-MDLP unit |
---|---|---|---|
SP stereo | SP stereo | SP stereo | SP stereo |
SP mono | half-speed SP mono | half-speed SP mono | |
LP2 | silent | SP stereo | |
LP4 | silent | half-speed SP mono | |
SP mono | SP stereo | double-speed SP mono | double-speed SP mono |
SP mono | SP mono | SP mono | |
LP2 | silent | double-speed SP mono | |
LP4 | silent | SP mono | |
LP2 | SP stereo | silent | silent |
SP mono | silent | silent | |
LP2 | LP2 | silent | |
LP4 | nonstop squeal | silent | |
LP4 | SP stereo | silent | silent |
SP mono | silent | silent | |
LP2 | double-speed LP4 | silent | |
LP4 | LP4 | silent |
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 Mode | ||||
---|---|---|---|---|
305MB Hi-MD formatted Minidisc | 1GB Hi-MD Media | recording with Hi-MD equipment | downloading from PC to Hi-MD equipment |
|
Linear PCM 1411kbps (1.4Mbps) | 28m | 1h 34m | yes | yes |
ATRAC3plus 256kbps “Hi-SP” | 2h 20m | 7h 55m | yes | yes |
ATRAC3plus 64kbps “Hi-LP” | 10h 10m | 34h | yes | yes |
ATRAC3plus 48kbps | 13h 30m | 45h | no | yes |
ATRAC3 132kbps “LP2” | 4h 50m | 16h 30m | no | yes |
ATRAC3 105kbps | 6h 10m | 20h 50m | no | yes |
ATRAC3 66kbps “LP4” | 9h 50m | 32h 50m | no | yes |
ATRAC 292kbps “SP” | Not supported on Hi-MD media |
Source for table below: MD Discam
Current MD format | Existing MD formatted into “Hi-MD” | Hi-MD 1GB Disc | MD Data Disc | ||||||
---|---|---|---|---|---|---|---|---|---|
Data Capacity | 177MB | 305MB | 1.0GB | 650MB | |||||
Magneto-Optical Recording Method | Magnetic Field Modulation | Magnetic Field Modulation | Domain Wall Displacement Detection | Magnetic Field Modulation on two layer medium (record layer and record assist layer) | |||||
Laser Wavelength (λ) | 780nm | 780nm | 780nm | 655nm | |||||
NA of Objective Lens | 0.45 | 0.45 | 0.45 | 0.52 | |||||
Diameter | 64.8mm | 64.8mm | 64.8mm | 64.8mm | |||||
Thickness of Substrate | 1.2mm | 1.2mm | 1.2mm | 1.2mm (but with new substrate resin) | |||||
Tracking Format | Groove Recording | Groove Recording | Groove Recording | Groove Recording | |||||
Addressing | Wobbling Groove (ADIP) | Wobbling Groove (ADIP) | Wobbling Groove (ADIP) | Interlaced Wobbling Groove (ADIP with 1 address per track) | |||||
Data Modulation | EFM | 1-7RLL | 1-7RLL | 1-7RLL | |||||
Data Detection | Bit by Bit | PRML | PRML | Bit by Bit | |||||
Bit Length | 0.59μm | 0.44μm | 0.16μm | 0.34μm | |||||
Shortest Mark Length | 0.83μm | 0.58μm | 0.21μm | ||||||
Track Pitch | 1.5μm | 1.5μm | 1.25μm | 0.95μm | |||||
Data Transfer Rate | 1.25Mbps @1.2m/s | 4.37Mbps @2.4m/s | 9.83Mbps @1.98m/s | 9.4Mbps |
Data MiniDiscs
Only readable/writeable in MD Data drives and devices.
MD Data: 140MB Released July 1993
MD Data2: 650MB Released early 1997
Hi-MD: 1GB Exception, as all Hi-MD recorders will show up as a USB mass storage device