A Multimedia Compact Disc is a CD-ROM that has a storage space of 3.7GB on a single side.
It was a format backed by Sony and Philips. It was announced in December 1994 was referred to as High-Density CD or HDCD.
It was later renamed MMCD.
A month later, a similar high-density format was announced. It was called Super Density Compact Disc (SD CD).
MMCD was created with the intention of solving the limited storage space available on a standard CD-ROM.
It was later, along with Super Density Disc, to serve as an inspiration for the DVD.
How Does MMCD Work?
MMCD uses high-density coding to allow up to 4.5 hours of video on a single side of the disc.
This is done by shrinking the wavelength of the reading laser and making data storage pits smaller. More pits mean more storage space,
The MultiMedia CD employs a red laser with a wavelength of 635 nanometers.
The MultiMedia CD uses MPEG-2 encoding. This is a smart coding method compared to MPEG-1.
With MPEG-1, the data rate is constant. MPEG-2 on the other hand allows variable data rates.
It allocates data according to the type of scene in a video. More data is allocated for fast motion scenes to ensure smooth playback,
For ‘calmer’ talking head scenes, the data rate is reduced. This frees up more space on the disc.
Single Layer MMCD
A single layer MMCD can hold 3.7GB of data. This is 5.5 times that of a CD-ROM. It translates to 135 minutes of MPEG-2 quality video.
A two-channel soundtrack and 5.1 channel surround sound are supported. It is also compatible with Dolby Pro Logic and other MPEG audio formats.
Double Layer MMCD
The dual-layer MMCD was developed by 3M.
It boasted a storage capacity of 7.4GB. That’s 11 times the storage space of a music CD.
Video playback time is available up to 270 minutes.
Supported Video Aspect Ratio and Features
The Multimedia Compact Disc supports 4:3 and 16:9 video aspect ratios.
Disc Features supported include:
- copy protection’
- parental lock
- multi-speed fast forward
- reverse scan
- language support – 3 to 5 languages
- subtitle support – 4 to 6 languages
- support for NTSC and PAL
- line resolution up to 720 pixels
An MMCD player is backward compatible with CD-ROM and audio CD.
Take a look at the video below to see how the MMCD player works.
MMCD vs SD Disc : Format War?
As mentioned earlier, MMCD had a rival in the form of Super Density Disc promoted by Toshiba and Time Warner.
The SD Disc format was announced in January 1995, about a month after MMCD was introduced.
The two formats weren’t compatible with each other.
A format war looked set to break out. The industry was concerned. The competing formats were a potential no-win situation for equipment manufacturers and consumers.
Much to everyone’s relief, the MMCD group and the SD Alliance decided to work together on a single format.
Video Magazine October 1995
The Digital Revolution and Governance by Xiudan Dai