Sierra Video UPC-166 - Manual (Page 22)

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UPC-166 Functional Description
AES Audio Input Advanced Features
AES Sample Rate Converter
The UPC-166 AES inputs have sample rate converters that can be
independently enabled for each AES pair to allow the card to interface with
asynchronous AES sources (sources in which AES timing does not match
the video input timing). The sample rate converters are set to disabled
(bypassed) by default; 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 or embedded audio signal, SRC is automatically
bypassed along with gain and polarity controls.
Zero-Delay Audio Embedding
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 embedded into
video with no latency, additional delay may not be tolerable. Using zero-delay
embedding, the video can then 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.
When zero-delay audio embedding is enabled for a given AES pair, the pair is
directly embedded into its corresponding group (for example, AES Pair 1
into embedded channels 1 and 2; AES Pair 2 into embedded channels 3 and
4, and so on) with the normal frame sync audio delay being bypassed.
This function overrides the audio routing system (for example if AES Pair 1 is
selected, then the controls to route AES Pair 1 into other embedded channels
will not apply). Gain and polarity control is not available when this option is
selected. Zero-delay audio embedding is set to Off by default.
Low-Latency AES Passthrough
This function is similar to zero-delay audio embedding. 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.
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.
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MANUAL UPC-166-OM
(V4.0)