Mean amplitude of a .wav in C#

Question

Does anyone know a way to get the mean amplitude of a .wav file using C# (even if it means calling an outside command line program and parsing the output)? Thanks!

Answer 1

Here is a snip that reads in a stereo wav and puts the data in two arrays. It's untested because I had to remove some code (converting to mono and calculate a moving average)

    /// <summary>
    ///  Read in wav file and put into Left and right array
    /// </summary>
    /// <param name="fileName"></param>
    private void ReadWavfiles(string fileName)
    {
        byte[] fa = File.ReadAllBytes(fileName);

        int startByte = 0;

        // look for data header
        {
            var x = 0;
            while (x < fa.Length)
            {
                if (fa[x]     == 'd' && fa[x + 1] == 'a' && 
                    fa[x + 2] == 't' && fa[x + 3] == 'a')
                {
                    startByte = x + 8;
                    break;
                }
                x++;
            }
        }

        // Split out channels from sample
        var sLeft = new short[fa.Length / 4];
        var sRight = new short[fa.Length / 4];

        {
            var x = 0;
            var length = fa.Length;
            for (int s = startByte; s < length; s = s + 4)
            {
                sLeft[x] = (short)(fa[s + 1] * 0x100 + fa[s]);
                sRight[x] = (short)(fa[s + 3] * 0x100 + fa[s + 2]);
                x++;
            }
        }

        // do somthing with the wav data in sLeft and sRight
    }

Answer 2

The NAudio library for .NET sounds like your best bet. It allows access to the waveform of an audio file, which can loop over to calculate the value of the mean ampltiude.

Answer 3

Normally the root-mean-squared method is used to calculate the "mean" amplitude of sin(x)-like signals.