Grass Valley Imagestore 750 v.3.0.1 - Manual (Page 123)

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Imagestore 750
User Manual
As the Dolby data passes through the audio engine, it is treated as pure data and left
untouched. No decompression or re-compression is performed. Dolby E data streams can be
switched cleanly, and the cut point is configured to synchronize with one of the following posi-
tions of the audio A/B mixer:
• Transition start.•Fully at A
• Transition mid-point (default).•Fully at B
• Transition end.
Any metadata in the data stream is also switched at this point.
Because all Dolby data remains compressed throughout the system, it is not possible to apply
audio A/B-mixing or voice-overs on systems having no Dolby modules. To do this requires Dolby
decode option(s) to be installed.
The following diagram shows an Imagestore 750 without any Dolby options installed.
Embedded audio from the sources consists of a mixture of PCM and Dolby E, for example, stereo
2.0 PCM on channels 1 and 2 and Dolby E on channels 3 and 4. The PCM channels are A/B-mixed
and a voice-over is applied; but only A/B-switching is performed on the Dolby E channels. The
two stems are then recombined so the embedded output matches the source format:
Fig. 6-2: Basic Audio Engine - A/B switching Dolby E Audio
For other Dolby applications, the respective Dolby hardware and software options are required.
These are described in the following sections.
Installing Dolby Options
The Imagestore 750’s Dolby options provide additional integrated Dolby decoding and
encoding capability.
Voice-
Over
Audio A
/B M
ix
er
A Input
B Input
Preview Out
PCM
Dolby
D
olb
y A/B
Swit
ch
Dolby
Dolby
PCM
PCM
Dolby
PCM
PCM
PGM
PVW
A
B
Program Out