Cobalt Digital COMPASS 9301 AES Audio Delay - Manual (Page 17)

9301-OM (V4.2) 9301 PRODUCT MANUAL 1-13
Introduction
9301 Functional Description
AES Audio Input Advanced Features
AES Sample Rate Converter Bypass
The 9301 AES inputs have sample rate converters that are enabled by default.
This allows the card to interface with asynchronous AES sources (sources in
which AES timing does not match the selected reference timing). The sample
rate converters can be bypassed with a control on DashBoard™ and/or the
Cobalt
® Control Panel, or via the front panel card controls; this is necessary
when embedding non-PCM AES audio such as Dolby ® E or Dolby ® Digital
audio streams. When a valid Dolby ® E or Dolby ® Digital signal (in
accordance with SMPTE 337M) is detected on an AES signal, SRC is
automatically bypassed along with gain and polarity controls. Bypass (SRC
Disable) is set to Off by default.
Low-Latency AES Passthrough
In cases where additional delay must be avoided, it may be desirable to embed
AES with minimum latency. For example if Dolby E
® is to be transferred,
additional delay may not be tolerable. Using low-latency passthrough, video
can eventually be delayed by one frame to account for the Dolby E
® encoding
delay. In this manner, any delay between video and audio can be cleanly
contained within one frame period. If low-latency AES passthrough is
selected for a given input pair, it causes the corresponding AES output pair to
act as a bit-for-bit copy of the corresponding AES input pair.
Passthrough can be enabled with a control on DashBoard™ and/or the
Cobalt
® Remote Control Panels. This control overrides the normal audio
routing and delay. Gain and polarity control is not available when this option
is selected. Passthrough is set to Off by default.