Grass Valley NVISION Compact CQX - Manual (Page 99)

Compact Router System Configurator • User’s Guide 87
12. Tutorials
Products
The “AES” routers switch AES3id audio. The AES routers switch in sync with a video reference if
one is present.
The two AES modes have different functional characteristics:
• Synchronous mode.
This mode is intended for 48kHz input. However, the router accepts input from 32kHz to
192kHz. The router produces AES3id output at 48kHz using adds and drops, as required. If
the input itself is locked to the video reference, no adds or drops occur.
When the source and output AES streams are not in sync, AES samples arrive at a rate
different from the rate at which they leave the router. Add: when the source is slower than
the output, router software occasionally inserts an extra copy of the most recent sample in
the output stream until the source and output are back in sync. Drop: when the source is
faster than the output, software occasionally does not send the sample(s) to the output until
the source and output are back in sync again. Adds and drops are performed on a minute
scale, never in large blocks, keeping perceptible distortions to a minimum.
The 16×16 router supports either 16×16 stereo switching or 32×32 mono channel switching
(when controlled by an external control system). The 32×32 router supports either 32×32 ste-
reo switching or 64×64 mono channel switching (when controlled by an external control sys-
tem).
A control panel cannot and does not perform mono switching. It is only in external
software (CRSC, CRConfig, NV9000, or third-party software) that you can do that and then
only when the router is in synchronous mode (i.e., has a video reference).
• Asynchronous mode.
The router passes the input stream (32kHz–192kHz) transparently to the output with no audio
processing. The output is the same as the input and the output rate is the same as the input rate.
Because the router does no audio processing, it performs stereo switching only.
AES routers power up in asynchronous mode. If a video reference is present, the router immedi-
ately switches to synchronous mode. If no video reference is present, the router stays in asynchro-
nous mode.
If a video reference is applied at any time after power-up, the router immediately switches from
asynchronous to synchronous mode.
Important When the router is in synchronous mode, and video reference is lost, the router
waits 15 minutes (a “grace” period) before reverting to asynchronous mode. If you
need to switch from synchronous mode to asynchronous mode in less than 15 min-
utes, you can cycle power to the router with the video reference disconnected.