Grass Valley NV7512 v.1.3 - Manual (Page 102)

92 Rev 1.3 • 10 Oct 08
4. Configuration
Setting MADI Channels
Setting MADI Channels
MADI audio signals are grouped into 32-bit packets for each audio channel with one MADI frame
composed of up to 64 continuous channels. MADI signals require a reference in accordance with
AES11 standards. (See
MADI Reference on page 67.) Signals are received and distributed through
two BNC connectors. Using DIP switches on the MADI input card and the MADI output card, the
signals being received and distributed can have several attributes set, as follows:
• Allocate channels between the two BNC connectors (Input 1 and Input 2).
• Set sample rate and if standard or legacy for Input 1 and Input 2 MADI channels can be
received and distributed at sample rates of 48 kHz or 96 kHz.
• Choose to pass through channel status data in its current state or force it into a known profes-
sional state.
Forcibly adding common, professional channel status data is called “channel status stripping.” It is
useful in instances where the signal channels have been recombined and the channel status data
may have been corrupted. If the sample rate of the MADI signals is being changed, the channel sta-
tus data is automatically removed and channel status stripping applied by default.
Standard and Legacy Formats
When a MADI stream is set to a sample rate of 96kHz, the number of samples is 2:1 compared to
48kHz, which is 1:1. Because there are twice the number of samples in the same period of time, the
samples can be organized consecutively (1, 2, 3, 4...) or interlaced (1, 2, 1, 2...). Consecutive order-
ing is known as ‘standard’ format and interlacing as ‘legacy’ format. Using the ‘STD MODE/LEG-
ACY MODE’ switch on the card, the incoming or outgoing MADI stream format can be matched
to the format of the signal being received or the facility receiving the distributed signals.
By default, all switches on the DIP switch are set ‘OFF’ — the left position — corresponding to a
synchronous audio rate of 48kHz and 64 channels.