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Multichannel Audio Digital Interface, MADI or AES10 is an Audio Engineering Society (AES) standard electronic communications protocol that defines the data format and electrical characteristics of an interface that carries multiple channels of digital audio. The AES first documented the MADI standard in AES10-1991, and updated it in AES10-2003 and AES10-2008. The MADI standard includes a bit-level description and has features in common with the two-channel format of AES3. It supports serial digital transmission over coaxial cable or fibre-optic lines of 28, 56, or 64 channels; and sampling rates of up to 96 kHz with resolution of up to 24 bits per channel. Like AES3 or ADAT it is a Uni-directional interface (one sender and one receiver). == Transmission format == MADI links use a transmission format similar to Fiber Distributed Data Interface (FDDI) networking (ISO 9314), which was popular in the mid-'90s for backbone links between LAN segments. Since MADI is most often transmitted on copper links via 75 ohm coaxial cables, it more closely compares to the FDDI specification for copper-based links, called CDDI. AES10-2003 recommends using BNC connectors with coaxial cables (see part 7.1.4) and ST1 connectors with optic fibres (see part 7.2.1). The specifications about fibres can provide a range of up to 2 km. The basic data rate is 100 Mbit/s of data using 4B5B encoding to produce a 125 MHz physical baud rate. Unlike AES3, this clock is not synchronized to the audio sample rate, and the audio data payload is padded using "JK" sync symbols. The audio data is almost identical to the AES3 payload, though with more channels. Rather than letters, MADI assigns channel numbers from 0–55 or 0–63. The only difference is that frame synchronization is provided by sync symbols outside the data itself, rather than an embedded preamble sequence, and the first four time slots of each sub-channel are encoded as normal data, used for sub-channel identification: * Bit 0: Set to 1 to mark channel 0, the first channel in each frame * Bit 1: Set to 1 to indicate that this channel is active (contains interesting data) * Bit 2: notA/B channel marker, used to mark left (0) and right (1) channels. Generally, even channels are A and odd channels are B * Bit 3: Set to 1 to mark the beginning of a 192-sample data block Sync symbols may be inserted at any subframe boundary, and must occur at least once per frame (0.45% minimum overhead.) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「MADI」の詳細全文を読む スポンサード リンク
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