MADI

The Multichannel Audio Digital Interface ( MADI ) is a digital interface for multichannel audio transmission, which is mainly used in audio engineering. It is standardized as AES10 of the Audio Engineering Society.

History

In the 80s, the audio industry was looking for new and more modern transmission options and formats to many audio channels to transmit through a cable at the same time and to develop an alternative to expensive and cumbersome multicores in live and studio operation. To focus these efforts, the MADI Group, consisting initially formed from Sony, Mitsubishi, Neve and SSL. The aim was to develop a lossless and insensitive data transmission format, which was finally defined in 1989 at the AES standard AES10. It was the birth of the " Multichannel Audio Digital Interface" ( MADI ).

The first official definition of this format was the AES10 - 1991. It was followed by updates in the years 2003, 2005 and 2008. AES10 - 1991 MADI defined with a resolution of 24 bits at 32 kHz to a maximum of 49 kHz, with a tolerance of 12.5%.

This tolerance is under the name " Varispeed " known and was necessary for the earlier tape machines. 's AES10 - 1991 MADI was set to 56 channels. , This changed with the revision of 2003. At this time, tape machines less and less were used was makes it possible to " Varispeed " to dispense and for increasing the possible number of channels. The user now stood 64 channels with a resolution of up to 48 kHz.

The maximum possible resolution has been revised with the revision of 2003 and similar to the method with ADAT was waiving in the audio channel number, the possible sampling rate is increased to 96 kHz. With the AES10id -2005, ultimately, resolutions were possible up to 192 kHz.

Technology

A MADI connection can both optical (FDDI ) and from coaxial cables (75 Ohm) exist and contains 28 or 32 AES / EBU audio channels as well as additional synchronization signals. Since AES / EBU is a proprietary format ( for two mono channels with up to 48 kHz/24 bit), MADI thus combines in principle the individual channels of a different format. The different channel number depends on whether you need the pitch control with ± 12.5 % change in velocity.

MADI can simulate up to 56 ( with Varispeed ) and 64 mono channels transmitted (without Varispeed ) in one cable. Thus, a lot more channels significantly fewer lines can be transferred, as for example with the ADAT, TDIF, S / PDIF or AES / EBU is possible. Today MADI can even meet with a sampling rate up to 192 kHz. This is very interesting especially for studio wiring and allows the technical expansion of existing production environments, the positive aspect of less cabling at LIVE applications to some stand out more than in fixed installations. MADI is considered very fault tolerant and resource-efficient protocol. It is particularly suitable for complex digital studio projects, since the individual channels may be present as AES / EBU, for example, at a signal matrix again, which also can be distributed individually via cable back then.

Specification

  • Original resolution and quantization Sampling Rate: 32 kHz to 48 kHz, / - 12.5 %
  • Sampling depth: 16 bit to 24 bit
  • Up to 64 mono channels in an optical or coaxial cable
  • Cable length max. 100m (coaxial ) or 2,000 m (optical)
  • Transfer Rate: 125 Mbits / s
  • Data transfer rate: 100 Mbit / s
  • Maximum data transfer rate: 96 768 Mbits / s = 56 channels at 48 kHz
  • Minimum data transfer rate: 50,176 Mbits / s = 56 channels with 32 kHz
  • Standard ( 1991): 56 channels / 24-bit / 44.1 kHz - 48 kHz / ± 12.5 % varispeed
  • Standard ( 2003): 64 channels / 24-bit / 32 kHz - 48 kHz
  • Double Wire 96/48k mode: 32 channels / 24-bit / 96 kHz
  • Quad Wire 192/48k mode: 16 channels / 24-bit / 192 kHz
Audio signal Solid State Logic Audio bit depth
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