Grass Valley Imagestore 750 v.3.0.1 - Manual (Page 132)

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Advanced Audio
Dolby
The audio latency for pass-through mode can be set either to match the encoding latency or to
the minimum. The latency reduction parameter sets the number of sample periods (at 48
kHz)
by which the encoding delay is reduced from the maximum value of 1 frame.
The encoding bit depth parameter can be set to 20 bits (8-channel Dolby E) or 16 bits (6-channel
Dolby E).
Dolby Digital Encoder Module
(The part number is CAT559D.)
The Dolby CAT559D module provides Dolby Digital (AC-3) encoding. The module accepts up to
6 channels of audio, as well as a metadata bitstream. The module outputs a stereo pair
containing either encoded Dolby Digital, or PCM when in pass-through mode:
Fig. 6-12: Dolby CAT555D module Input/Output
Fig. 6-13: Imagestore 750 Configurator - Audio Graph Dolby Encoder representation
The delay through the module is 6 frames. You should apply an appropriate video delay to
compensate for this.:
Oxtel automation commands exist for controlling the module’s encoding modes. (See Automa-
tion Control on page 119.)
The following encode modes are supported:
Encode Audio is encoded.
Pass-through Audio is passed through the module.
Follow decoder The encoder follows a decoder’s decode status. (When it decodes, the
encoder will encode.)
The audio latency for pass-through mode can be set either to match the encoding latency or to
the minimum. The encoder latency can be set between 187
ms (default) and 450 ms.
The encoder supports the following bitstream formats: