Junger Audio C8612 - Dolby® D/D+/AAC encoder - Manual (Page 17)

digital audio
modular
processing system
C8000
Dolby Digital / Digtal plus / Pulse (AAC) encoder
C8612
17/20
Below a sketch to illustrate the respective parameters of the ducker in relation to main program and
the voice over feed before it will be mixed :
Warble Tone
Warble Tone is a legacy technology developed by the BBC to help
production, storage and transmission of AD (audio descriptive)
content. It is a control signal that has the information about voice
channel mono panning and main program (external program)
fading. It is digitally encoded and placed on one track of a two
track signal. The other track contains the voice over signal. This
makes it easy to store such AD content on the other two tracks of a
4 track VTR or move it as a 2 track signal in parallel to the main
stereo to the transmission site. At the transmission site in the past
an extra so called Broadcast Mix was done and a second audio
program (e.g. in dual language transmission format) was created.
This enables the viewer of a movie or a TV show to select either
the main program or the Audio Description program. In the old days
of analog stereo transmission the left channel carried the main
program converted to mono and the right channel the AD mono
mix. When digital TV showed up and provided 4 audio tracks for
transmission, both programs have been transmitted in stereo.
Everybody will understand that this eats up a lot of precious
bandwidth … Today we are able to do the receiver mix and it needs
much less bandwidth to transmit just the voice over channel and a
few control parameter which can be encoded in parallel to the main
program to save more bandwidth. In a single PID transmission
format it allows to use the technology of transmitting MPEG
encoded stereo audio in parallel to Dolby Digital plus encoded
stereo and audio descriptive channel. In this case the existing
Warble Tone content can still be used. The C8612 simply decodes
the Warble track and translates this into mixing meta data.
Warble Tone [Off, On]
Control Mode This turns the Warble Tone operation on. You must provide Warble
Ton signal to input 7/8 of the C8612 (see functional graphic).
Warble Tone [last used, internal, auto]
Reversion Mode If there is a lost of Warble Ton you can decide what to do.
External
Program
Scale
Factor
voice over signal
Trigger Level
Trigger Delay
Duck Attack
Trigger Hold
Duck Release
main (external) program signal