View source for Normalize

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{{AvsPlusFullname}}<br>
Up-to-date documentation: [https://avisynthplus.readthedocs.io/en/latest/avisynthdoc/corefilters/normalize.html https://avisynthplus.readthedocs.io]
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Raises (or lowers) the loudest peak of the audio track to a given {{FuncArg|volume}}. This process is called [[Wikipedia:Audio_normalization|''audio normalization'']].<br>
Note that '''Normalize''' performs [[Wikipedia:Audio_normalization#Peak_normalization|''peak normalization'']] (used to prevent audio [[Wikipedia:Clipping_(audio)#Digital_clipping|clipping]]) and not [[Wikipedia:Audio_normalization#Loudness_normalization|loudness normalization]].

==== Syntax and Parameters ====
{{FuncDef
|Normalize(clip ''clip'' [, float ''volume'' , bool ''show'' ] )
}}

:{{Par2|clip |clip|}}
::Source clip. Supported [[ConvertAudio|audio sample types]]: 16-bit integer and [[Float|32-bit floating-point]]. 
::Other sample types (8-, 24- and 32-bit integer) are automatically converted to floating-point.  

:{{Par2|volume|float|1.0}}
::Set the amplitude of the loudest audio. Default = 1.0 for peaking at 0[[Wikipedia:DBFS|dB]]: for [[Float|floating-point]] samples, this corresponds to the range -1.0 to +1.0, and for 16-bit integer samples, this corresponds to the range -32768 to +32767 &ndash; the widest range possible without [[Wikipedia:Clipping_(audio)#Digital_clipping|clipping]]. 
::*For a particular peak [[Wikipedia:Decibel|decibel]] level, use the equation {{FuncArg|volume}} = {{Serif|10}}<sup> {{Serif|'''dB''' / 20}}</sup>
::*For example, set a -3dB peak with {{FuncArg|volume}} = 10<sup>-3/20</sup> or 0.7079.
::*Where multiple audio channels are present, all channel gains are set in proportion. For example, if the loudest peak on the loudest channel comes to -10dB, by default a gain of +10dB is applied to all channels.

:{{Par2|show|bool|false}}
::If ''true'', a text overlay (see image below) will show the calculated amplification factor and the frame number of the loudest peak.

==== ''Normalization and Floating-point Audio'' ====
The idea of digital ''clipping'' (when the signal is outside the range that can be stored accurately) really applies only to ''integer'' sample types; floating-point samples will never become clipped in practice, as [[Wikipedia:Single-precision_floating-point_format|the maximum value]] is around 3.4×10<sup>38</sup> &ndash; some 29 orders of magnitude (580 dB) larger than 16-bit samples can store. 

'''Normalize''' is therefore not needed for floating-point audio, but using it is recommended before [[ConvertAudio|converting]] to an integer type, especially if any processing has been done &ndash; such as [[Amplify|amplification]], [[MixAudio|mixing]] or [[SuperEQ|equalization]] &ndash; which may expand the audio peaks beyond the integer clipping range. 

==== Examples ====
* Normalize signal to 98%
<div {{BoxWidthIndent|44|2}} >
 video = [[AviSource]]("video.avi")
 audio = [[WavSource]]("audio.wav").Normalize(0.98)
 return [[AudioDub]](video, audio)
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* Normalize each channel separately (eg for separate language tracks)
<div {{BoxWidthIndent|44|2}} >
 video = [[AviSource]]("video.avi")
 audio = [[WavSource]]("audio2ch.wav")
 left_ch = [[GetChannel]](audio,1).Normalize
 right_ch = [[GetChannel]](audio,2).Normalize
 return [[AudioDub]](video, [[MergeChannels]](left_ch, right_ch))
</div>

* Effect of {{FuncArg|show}}=true with added [[Histogram]], [[Waveform]] and [[Runtime_environment#Special_runtime_variables_and_functions|current_frame]] overlays
<div {{BoxWidthIndent|44|2}} >
 LoadPlugin(p + "[[Waveform]]\waveform.dll") 
 V=[[BlankClip]](pixel_type="YV12", width=480, height=360).[[Loop]]
 A=[[WavSource]]("music.wav")
 [[AudioDub]](V, A).[[AudioTrim]](0.0, A.[[Clip_properties|AudioDuration]])
 [[ScriptClip]](Last, 
 \ """[[Subtitle]](Last, "frame "+[[Internal_functions#String|String]]([[Runtime_environment#Special_runtime_variables_and_functions|current_frame]]), align=5)""")
 Normalize({{FuncArg|volume}}=1.0, {{FuncArg|show}}=true)
 [[Histogram]](mode="audiolevels")
 [[Waveform]](window=3)
 return Last
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:[[File:NormalizeEx2_v1,0.png]]
:(showing frame 2744 where the loudest peak was detected, but note that ''Amplify Factor'' is the same for all frames)



[[Category:Internal filters]]
[[Category:Audio_filters]]