O3A Brickwall

Host Support

Audio

Controls

• Limit

Description

This plugin ensures that the amplitude of all channels in the signal are below a particular limit. It does this by applying a "brick wall" limiter with a fast attack to the signal. The limiter is triggered when the signal is within a decibel of the target level (or above). When the limiter is triggered it reduces the level of the signal aggressively, reducing all channels by the same gain. When the limiter is not triggered the signal passes through unmodified.

A meter shows how much the level is currently reduced, along with the extreme used in the last ten seconds.

For instance, this can be used for safety when exporting to a fixed-point PCM file, to ensure that no signals clip. The sound may have artefacts but generally these are far better than clipping.

If you are looking for dynamic range control plugins for artistic reasons, you may also want to consider the O3A Compressor from the O3A Manipulators plugin library.

The plugin is available in the O3A Decoding plugin library.

Controls

Control: Limit

This control determines the level above which the output may not go. Values are in decibels and a value of 0dB corresponds to a "full scale" signal and is the default. Please note that this convention is not the convention used by the O3A metering plugins, so values will not correspond directly.

Note that subsequent external processing such as sample rate conversion can result in higher signal peaks. To allow a little extra headroom, you may wish to reduce the limit value by a few decibels.