CODEWITHSUNDEEP
c#normalizationnaudio
DirtyNative
DirtyNative

Reputation: 2834

NAudio Normalize Audio

I am trying to normalize Mp3-Files with NAudio but I don't know how to do so.

The first I did was converting the Mp3-File to PCM:

using (Mp3FileReader fr = new Mp3FileReader(mp3.getPathWithFilename())) {
    using (WaveStream pcm = WaveFormatConversionStream.CreatePcmStream(fr)) {
        WaveFileWriter.CreateWaveFile("test.wav", pcm);
    }
}

But what is the next step? Unforntunately I didn't find anything on the net.

Thanks for your help

Upvotes: 1

Views: 1192

Answers (1)

Tom McCaffrey
Tom McCaffrey

Reputation: 121

I'm new to NAudio, so I don't exactly know how to code this, but I do know that normalization of an audio file requires two passes through the data. The first pass is to determine the maximum and minimum data values contained in the file - so you would have to scan each data point and determine the max and min data points (and for both channels if stereo). Then, upon determining the highest max or lowest min (whichever absolute value is highest), you calculate that value as a percentage from Full Scale (the highest or lowest possible value for the bit stream, for example with 16-bit audio it's 32767 or -32768). You then increase the volume by the difference in percentage.

So for example on your scanning pass, you discovered that the highest value in a 16 bit mono file was 29000, you would then increase the volume by 112.989 percent so that the maximum sample is increased from 29000 to 32767, and all other samples are increased accordingly.

Upvotes: 1

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