Avid Technology HD MADI, Manual, Page: 24 / 36

HD MADI Guide 20
When using Varispeed, or when working with
higher sample rates, any unavailable channels
become grayed out in the I/O Setup dialog.
HD MADI VSO Range
When using Varispeed with HD MADI, it is pos-
sible to exceed the available bandwidth. When
Varispeed exceeds the maximum frequency for
the current nominal sample rate, audio drops
out. The maximum frequency for Varispeed at
each nominal sample rate is listed in Table 2.
Sample Rate Conversion
Input
Enable the
Input
option to apply sample rate
conversion on input. Select this option if
HD MADI is receiving external MADI sources at
any sample rate other than the Pro Tools Session
sample rate.
Clock Source
Select the desired Clock Source option to set the
clock source for Sample Rate Conversion (SRC)
on input.
SRC Word Clock In 1
Select this option to clock
to the SRC Word Clock In 1 port for SRC.
SRC Word Clock In 2
Select this option to clock
to the SRC Word Clock In 2 port for SRC.
SRC AES/EBU
Select this option to clock to the
SRC AES/EBU port for SRC.
MADI IN
Select this option to clock to the incom-
ing MADI signal (Optical or Coaxial) for SRC.
Word Clock Base Frequency (44.1/48)
Enable this option if you are synchronizing to
Word Clock at either 44.1 kHz or 48 kHz, but
you are receiving input at a sample rate of
88.2 kHz or higher.
Input Rate
Select the correct input sample rate frequency
range for the incoming MADI signal:
• 44.1 kHz/48 kHz
• 88.2 kHz/96 kHz
• 176.4 kHz/192 kHz
Table 1. Available MADI channels by sample rate
Session
Sample Rate Full Channel
Count
Varispeed
Channel
Count
44.1/48 kHz 64 56
88.2/96 kHz 32 28
176.4/192 kHz 16 14
Table 2. Varispeed maximum sample rate limits
Nominal
sample rate Channel
Count Maximum
Frequency
44.1/48 kHz 64 48.8 kHz
44.1/48 kHz 56 55.6 kHz
88.2/96 kHz 32 97.5 kHz
88.2/96 kHz 28 111.5 kHz
176.4/192 kHz 16 194.9 kHz
176.4/192 kHz 14 223.0 kHz