AX AUX Bus Effects Overview

Introduction

The AX AUX Bus Effects library (AXFX) provides a set of premade effects ready to be applied to groups of AX voices using the AX AUX buses. These effects include multiple types of reverb, chorus, delay, I3DL2 reverb, Pitchshift, flanger, compressor and overdrive.

Usage

The steps required to make use of a given AXFX effect are as follows:

For an example of AXFX usage, see the following effects demos:

Sound 2 Effects

The Sound 2 effects are both algorithmically and qualitative improved over the Multi Channel effects provided. Two, four, and six-channel versions are provided. The available multi channel effects are as follows:
Effect Description
Reverb This is a highly optimized version of the multi-channel reverb. The resulting reverb effect is more defined and requires fewer CPU cycles than the multi-channel version.
Reverb I3DL2 An implementation of the I3DL2 reverb standard. This is a completely new reverb algorithm over the multi-channel effect and allows more detailed user control of reverb behavior. This effect requires 50% more CPU usage than the above reverb effect.
Delay This implements the equivalent multi-channel version while requiring fewer CPU cycles than the multi-channel version.
Chorus A more advanced chorus algorithm compared to the multi-channel version. A user parameter allows the user to adjust LFO feedback phase between each channel resulting in more complexity. This version requires more CPU cycles than the simpler multi-channel versions.
Compressor This effect is unique to the sound 2 library and is used to normalize sound volume.
Flanger This effect is unique to the sound 2 library and is a type of chorus effect.
Overdrive This effect is unique to the sound 2 library and is used to add distortion.
Pitchshift This effect is unique to the sound 2 library and is used to alter sound pitch.

Multi Channel Effects

The multi channel effects are both algorithmically and qualitatively improved over the legacy effects. (Legacy effects are only available in the sound 1 library). In addition, the multi channel effects support two, four, or six channels, while legacy effects only support two. These effects are superseded by the Sound 2 effects above.

The available multi channel effects are as follows:

Legacy Effects

These legacy effects have been retained from the Wii SDK. Each of these only supports two channels. Additionally, they each have expanded versions that provide more control over individual settings.

High-Quality Reverb

AXFX_REVERBHI
AXFX_REVERBHI_EXP

This library provides a high-quality reverb, appropriate for music and sound effects. Reverb controls are described below.

Reverb Control Description
Predelay The predelay is a value between 0.0 and 0.1 that specifies, in seconds, the length of time before the reverberation starts. This parameter is especially useful for large rooms as it simulates the latency for reflected sound waves. A larger value implies a larger distance between the emitter and reflecting surfaces.
Reverb time The time is a value between 0.01 and 10.0 and specifies, in seconds, the length of time before the reverberation decays. A value of 0.01 seconds specifies a small room while a value of 10.0 specifies a cathedral or stadium, for example.
Coloration The coloration is a value between 0.0 and 1.0. This value modulates the coefficients of the algorithm's all-pass filters and can be used to simulate the acoustic properties of the surfaces in a room.
Damping The damping is a value between 0.0 and 1.0 and modulates the algorithm's high-frequency attenuation. When damping is 0.0, lower frequencies are prevalent and the reverberation becomes more pronounced. As damping approaches 1.0, high frequencies are present and the reverberation becomes less pronounced.
Crosstalk The channel crosstalk is a value between 0.0 and 1.0 and describes the level of interaction between channels. A value of 0.0 means that the channels are strictly independent; that is, the reverberated signal derived from a given channel will be applied only to that channel. A value of 1.0 means that each channel contributes its reverberation signal to the other channels (as well as itself).
Mix The effect mix is a value between 0.0 and 1.0 and specifies the level of the reverberated signal as a fraction of the output. A value of zero means that only the original signal will be heard. A value of 1.0 means that only the reverberated signal will be heard.

Standard Reverb

AXFX_REVERBSTD
AXFX_REVERBSTD_EXP

The standard reverb effect uses fewer CPU cycles than the high-quality reverb. Programmers may find it sufficient for most applications. This effect has the following controls.

Standard Reverb Control Description
Predelay The predelay is a value between 0.0 and 0.1 that specifies, in seconds, the length of time before the reverberation starts. This parameter is especially useful for large rooms as it simulates the latency for reflected sound waves. A larger value implies a larger distance between the emitter and reflecting surfaces.
Reverb time The time is a value between 0.01 and 10.0 and specifies, in seconds, the length of time before the reverberation decays. A value of 0.01 seconds specifies a small room while a value of 10.0 specifies a cathedral or stadium, for example.
Coloration The coloration is a value between 0.0 and 1.0. This value modulates the coefficients of the algorithm's all-pass filters and can be used to simulate the acoustic properties of the surfaces in a room.
Damping The damping is a value between 0.0 and 1.0 and modulates the algorithm's high-frequency attenuation. When damping is 0.0, lower frequencies are prevalent and the reverberation becomes more pronounced. As damping approaches 1.0, high frequencies are present and the reverberation becomes less pronounced.
Mix The effect mix is a value between 0.0 and 1.0 and specifies the level of the reverberated signal as a fraction of the output. A value of zero means that only the original signal will be heard. A value of 1.0 means that only the reverberated signal will be heard.

Chorus

AXFX_CHORUS
AXFX_CHORUS_EXP

The chorus effect is intended for General MIDI-type synthesizer applications where a chorus is expected on the AuxB bus. The chorus has the following controls.

Chorus Control Description
Base delay The base delay is a value between 5 and 15. This value specifies, in milliseconds, the delay after which the input signal is mixed back into itself.
Variation The length of the base delay will vary over time. The delay variation is a value between 0 and 5, and specifies, in milliseconds, the maximum amount of time by which the base delay may be varied. When the base delay is at its boundary values (5 or 15 milliseconds), this parameter is ignored as there cannot be any variation.
NOTE:
This parameter is typically known as "chorus depth" in other products.
Period When variation is nonzero, the delay will vary continuously and periodically. The delay period is a value between 500 and 10000 and specifies, in milliseconds, the period of the delay variation. This parameter is typically referred to as "chorus rate" or "chorus speed" in other products.

Delay

AXFX_DELAY
AXFX_DELAY_EXP

The delay effect is a standard delay with feedback and output control. Delay has the following settings.

Delay Control Description
Delay The delay is a value between 10 and 5000 and specifies, in milliseconds, the delay after which the input signal is mixed back into itself.
NOTE:
Delay values must be specified for the left, right, and surround channels (in that order).
Feedback The feedback is a value between 0 and 100 and specifies the percentage at which the delayed signal will be mixed into the input signal.
Output The feedback is a value between 0 and 100 and specifies the percentage at which the delayed signal will be mixed into the input signal.

Revision History

2014/02/26 Describe differences between multi-channel.
2013/05/08 Automated cleanup pass.
2011/02/21 Initial version.


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