O3A Zoom and O3A Zoom XYZ

Host Support

O3A Zoom

O3A Zoom XYZ

Audio

O3A Zoom

O3A Zoom XYZ

Controls

• X
• Y
• Z
• Azimuth
• Elevation
• Distance
• Scene Size
• Gain Rolloff
• HF Rolloff

Description

This manipulator has similar controls to the O3A Panner LS plugin, but it does not pan mono sounds. Instead, its input is an entire O3A sound scene. It uses a change of perspective manipulation to give the impression that the listener or the entire O3A sound scene has moved. For instance, this can be used to move the listener towards a front stage, or move a 3D rainstorm recording in from the distance until we are in the middle of it. You may wish to combine its use with a rotation plugin to give more movement options.

The underlying algorithm used is very similar to the "Zoom" mode of the O3A Move plugin.

Two versions of the plugin exist. The only difference is the way that the controls are exposed to automation. The reason for this is that the X, Y and Z controls and the Azimuth, Elevation and Distance controls do essentially the same thing (move the sound) and so to avoid confusion, the plugins only expose one set of controls to automation. O3A Zoom exposes Azimuth, Elevation and Distance to automation, whereas O3A Zoom XYZ exposes X, Y and Z. This restriction only applies to automation; all controls are available in the user interface.

There are three control surfaces which can be used to move the scene "A" around. The main surface "B" is a view from above, with the front at the top of the screen. Below it is a view "C" from behind and another "D" from the right.

This plugin also has scene size controls and a distance model. The size is visible on the control surfaces. Units are nominally metres, but it is possible to give a sense of larger or smaller distances by changing the scene size and rolloffs.

This plugin does not change the time alignment of sounds.

The plugin is available in the O3A Manipulators plugin library.

View Support

When used with O3A View Sync from the O3A View library, this plugin can be connected to the separate View or ViewVR applications.

When this option is available, a 'View' button appears at the top right of the plugin's user interface.

When this is pressed, the plugin is connected to the View or ViewVR application and is displayed there.

Controls

Controls: X, Y and Z

The coordinates determine where the centre of the scene is in space. Units are nominally metres.

These coordinates are not available as automation parameters in O3A Zoom. Instead, they are translated to and from Azimuth, Elevation and Distance, which may be used instead. If you need to automate these controls you should probably use O3A Zoom XYZ instead.

When X, Y and Z are all zero, the scene passes through the plugin unmodified.

Controls: Azimuth and Elevation

Azimuth and Elevation control the direction of the scene relative to the centre.

Azimuth is the horizontal angle, between -180 to +180 degrees, measured anticlockwise (left) from the front. Elevation is a vertical angle between -90 and +90 degrees, measured with positive upwards and 0 on the horizontal.

For instance, the direction for azimuth +90 and elevation +45 can be found by turning 90 degrees to the left and then looking up by 45 degrees.

Azimuth, Elevation and Distance are not available as automation parameters in O3A Zoom XYZ. Instead, they are translated to and from X, Y and Z, which may be used instead. If you need to automate these controls you should probably use O3A Zoom instead.

Control: Distance

This control indicates how far away the centre of the scene is. Units are nominally metres. When the distance is zero, the scene passes through the plugin unmodified.

Azimuth, Elevation and Distance are not available as automation parameters in O3A Zoom XYZ. Instead, they are translated to and from X, Y and Z, which may be used instead. If you need to automate these controls you should probably use O3A Zoom instead.

Control: Scene Size

The scene size is the radius of the "bubble" containing the scene that is being moved. Units are nominally metres. Changing this allows better control of whether the listener is inside or outside the scene.

Control: Gain Rolloff

This rolloff determines the rule that is used to reduce the scene's level as it moves away. It is only applied when the listener is outside the scene. A value of 1 is closest to how this occurs in reality. Reducing the value reduces the effect of the level drop and increasing the value exaggerates it. A value of 0 means that the level stays constant.

Mathematically, the gain applied is determined by the inverse square law, but raised to a power given by this control.

Control: HF Rolloff

This controls a simple low-pass filter that reduces high frequency content as the source moves away. It is only applied when the listener is outside the scene. This happens in reality due to air absorption. A value of 0.1 is close to reality at typical pressure, temperature and humidity, and changing this value reduces or increases the effect. A value of 0 means that no filtering occurs.

The value used with this control is the number of additional decibels lost at 10kHz for each metre of distance, on top of the main gain rolloff.