8.2.1. MADI at High Sample Rates
The MADI standard (AES10) allows transport of audio at sample rates beyond 48 kHz by reducing the
number of available channels.
Double speed (88.2 kHz, 96 kHz)
Double speed audio signals can be transmitted and received in two different ways. Manufacturers can
implement one or both modes, usually referred to as "96k frame" and "S/MUX 2" or "legacy" mode. It is
important to use the same mode on both sender and receiver side because S/MUX 2 and legacy mode
are not compatible. Both modes transport the audio signal transparently.
96k frame
The so-called "96k frame pattern" (AES10) can be detected at the receiver side automatically. In this
mode, the frame numbers and corresponding user bits equal the number of channels submitted. The "56
Ch." setting corresponds to 28 audio channels at 88.2 kHz and 96 kHz sample rates. The "64 Ch." setting
corresponds to 32 audio channels at 88.2 kHz and 96 kHz sample rates.
S/MUX 2
Sample multiplexing (or S/MUX 2) describes a method to distribute two consecutive samples onto
neighboring channels. The MADI signal remains exactly the same as in single speed with 56 or 64
channels including its user-bits. The receiver decodes the audio signal by passing the samples of
channel 1+2 as two consecutive samples for channel 1, samples of channel 3+4 as two consecutive
samples for channel 2, and so forth. The amount of channels corresponds to the same as the 96k frame.
This format cannot be automatically detected at the receiver side.
Quad Speed (176.4 kHz, 196 kHz)
Quad speed MADI does not have a standardized frame format. Therefore S/MUX 4 is used. The encoding
works the same way as S/MUX 2, except that four consecutive channels are used to transport one audio
channel. This reduces the available number of channels to 14 ("56 Ch." setting) or 16 ("64 Ch." setting).
When using MADI, the sample rate of the incoming MADI signal and the expected frame
format of the outgoing MADI signal must be set in the device.
8.2.2. Connecting Two Identical MADI Signals for Redundancy
The coaxial MADI input can be configured to automatically switch to an existing MADI optical signal in
case the coaxial signal fails. While existing routing and clock settings from the coaxial MADI input are
kept, the port’s name is changed to
MADI Auto Input
and its icon changes to reflect the feature. The
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