Amplify / AmplifydB

Amplify and AmplifydB amplify the audio of the clip by the prescribed amount. You can specify different amount arguments for each channel. If there are more arguments than there are channels, the extra ones are ignored. If there are fewer arguments than channels, the last one is applied to the rest of the channels.

Amplify

Amplify the audio in linear values. See the Examples section for more information.

Syntax and Parameters

Amplify (clip, float amount [, float amount ]...)
clip
Source clip. Supported audio sample types: 16/32-bit integer, and 32-bit float.
Other sample types (8 and 24-bit integer) are automatically converted to 32-bit float.
amount

Multiply (scale) the audio by amount; values are linear:

  • amount > 1.0 increases volume

  • amount < 1.0 decreases volume

  • amount = 1.0 retains the same volume

  • Negative scale factors will shift the phase by 180 degrees (i.e. invert the samples).

AmplifydB

Amplify the audio in decibels. See the Examples section for more information.

Syntax and Parameters

AmplifydB (clip, float amount [, float amount ]...)
clip
Source clip. Supported audio sample types: 16/32-bit integer, and 32-bit float.
Other sample types (8 and 24-bit integer) are automatically converted to 32-bit float.
amount

Multiply (scale) the audio by amount; values are in dB (decibels):

  • amount > 0.0 increases volume

  • amount < 0.0 decreases volume

  • amount = 0.0 retains the same volume

Examples

The relation between linear and decibel gain control is:

lin = 10 (dB/20)

dB = 20·log10 (lin)

For example,

  • AmplifydB(  0.0) is equivalent to Amplify(1.0) (no change)

  • AmplifydB(  6.0) is equivalent to Amplify(2.0) (about twice as loud)

  • AmplifydB( -6.0) is equivalent to Amplify(0.5) (about half as loud)

  • AmplifydB( 20.0) is equivalent to Amplify(10) (much louder)

  • AmplifydB(-20.0) is equivalent to Amplify(0.1) (much softer)

More examples:

  • AmplifydB(+3, 0) increases the volume of the left channel by a small amount.

  • Amplify(-1, 1) inverts the phase of the left channel. See Wikipedia: Out Of Phase Stereo.

See Also

  • Normalize - with show=true, can show the maximum amplification possible without clipping.

  • How the multichannels are mapped can be found in the description of GetChannel.

Changelog

Version

Changes

AviSynth 2.5.7

Fixed a small memory leak in Amplify().

AviSynth 1.0.0

Added Amplify and AmplifydB filters.

$Date: 2022/03/05 15:10:22 $