# Auto Gain

Easy Effects Autogain is based on the library libebur128 which implements the EBU R 128 standard for loudness normalization. It changes the audio volume to a perceived loudness target that can be customized by the user.

# Target

Loudness level.

# Silence

Silence threshold. While the momentary loudness is below this value the autogain won't make any changes to the current gain being applied to the signal level.

# Maximum History

Range of time taken into account for the calculation of loudness level and output gain.

# Reference

The parameter used as reference to evaluate the output gain.

Momentary - Measures the loudness of the past 400 milliseconds.

Short-Term - Measures the loudness of the past 3 seconds.

Integrated - Ideally it indicates how loud the content is on average. It measures the loudness on a long range of time, depending on the value set as Maximum History.

Geometric Mean - Uses the geometric mean of all the above mentioned parameters, or two of them at user choosing.

# Reset History

Resets the Autogain history related to chosen Reference.

# Monitor Parameters

Autogain values shown as stats.

Relative - Used to detect silence. Whenever the Momentary term is below a predetermined threshold, modifications to the output gain will be disabled.

Loudness - The difference between its value and the target loudness determines the output gain.

Range - Indicates how large is the dynamic range of the content played.

Output Gain - The input signal is adjusted by this correction gain to bring its loudness to the target value.

# References

Wikipedia EBU R 128

EBU - Loudness Normalisation and Permitted Maximum Level of Audio Signals