Introduction
A Compound Audio Object (CAO) packages a project with complex signal flow into a single audio object, with clearly defined I/O pins. A custom panel created for the CAO provides user with integrated control interface. The following is a CAO created for Stereo Widening (SW) 2.0 as a reference project.
Stereo Widening 2.0 is a technology that utilizes amplitude panning to realize a stable and tunable phantom center image with minimal comb filtering and phasing artifacts, as well as tunable stereo side content for the perceived width. It has small MIPS/MEM footprint, and is suitable for larger speaker systems with minimum 4 channels.
In implementation, amplitude panning is used to shift side (de-correlated) content to rear speakers while mono part is panned to (phantom) center. The widening effect is applied to outer signal parts, possibly to emphasize reverberation, side-panned content, etc. Position of phantom center can be modified by the user, and its stability can be controlled by level setting of the mono part.
Signal Flow
Control Input
There are 3 control inputs for the end user. They are
- Angle of the Left content
- Angle of the Center image
- Angle of the Right content
Audio Input
The
SW 2.0
CAO has 2 input pins for standard stereo audio.
Audio Output
The SW 2.0 CAO has 4 output pins for a 4-speaker system (minimum) setup.
Main Panel
On the main panel, tuning and control parameters are accessible as follows:
- Left
: panning of left M/S encoded signal (limited to -90…0 deg.) - Right
: panning of right M/S encoded signal (limited to 0…+90 deg.) - Phantom
Center
: shift of phantom center (limited to +/-20 deg.) - Mater Gain
: controls the stereo input gain (SW processing only) - Stereo Strength
: gain of side (de-correlated) content - Mono Gain
: gain of mono (correlated) content - Presets
: different tuning sets and bypass mode - Mixer
: output gain of physical speakers and phantom center - Panning
LUTs
: opens the LUTs containing amplitude vectors - IN L/R Gains
: controls gains for left and right input channels - Output EQ L&R
: biquad EQs to adapt frequency response of output channels
STEREO WIDENING CAO 2.0 – .cao format and panel linking
From S+2 release CAOs are released in .cao file format, below section provides overview on panel linking for external control inputs to CAO.
- After importing the CAO, do double clicking on it, Panel will appears like this which is in below fig. Some of parameters are highlighted warning symbol in red mark, user need to link the panel elements with control inputs
- User need to take the corresponding control inputs pins as same as in mentioned figure and connect the signal to Panel from “Custom Panel to edit gallery”
- After connecting all control inputs in Panel, It should look like as mentioned main panel.