Grass Valley Imagestore 750 v.2.0.1 - Manual (Page 337)

Imagestore 750 User Manual Dolby Decode/Encode
Miranda Technologies Inc. Page 337
Dolby Handling on Legacy Systems
A standard Imagestore 750 (i.e. without Dolby modules) is able to pass and
switch between Dolby E data-streams; however Dolby Digital data is only
passed, not switched.
Audio processing is always carried out in parallel to the video keying. The
diagram below shows the basic engine:
As the Dolby data passes through the audio processing engine it is treated as
pure data and left untouched; so there is no decompression or re-compression
performed. The nature of Dolby E data-streams means they may be cleanly
switched, and cut-synchronised with the mid-point of the audio mixer. Any
metadata in the data-stream is also switched.
Since all Dolby audio remains compressed throughout the system, it is not
possible to apply audio AB-mixing or voice-overs on legacy systems.