Not sure if this will work on WP8, but you can try.
In WPF, I use NAudio. You can add it to your project via nuget.
After that, you can use the following snippet:
public static void Mp3ToWav(string mp3File, string outputFile) { using (Mp3FileReader reader = new Mp3FileReader(mp3File)) { WaveFileWriter.CreateWaveFile(outputFile, reader); } }
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