audio - C# How does the following code for Low Pass Filter run? -

i have following c# code low pass filter found on naudio site:

    public void setvalues(isampleprovider sourceprovider,int cutofffreq)     {         this.sourceprovider = sourceprovider;         this.cutofffreq = cutofffreq;          filter_lowpass();     }      private void filter_lowpass()     {         channels = sourceprovider.waveformat.channels;         filters = new biquadfilter[channels];          (int n = 0; n < channels; n++)             if (filters[n] == null)                 filters[n] = biquadfilter.lowpassfilter(44100, cutofffreq, 1);             else                 filters[n].setlowpassfilter(44100, cutofffreq, 1);     }      public waveformat waveformat { { return sourceprovider.waveformat; } }      public int read(float[] buffer, int offset, int count)     {         int samplesread = sourceprovider.read(buffer, offset, count);          (int = 0; < samplesread; i++)             buffer[offset + i] = filters[(i % channels)].transform(buffer[offset + i]);          return samplesread;     } 

where read function being called?

why need it?

i calling function filter_lowpass way:

        myfilter.setvalues(audiofilereader, currentcutoff);          waveout.init(myfilter); 

if want multiply each of samples constant value after passing through low pass filter, write code?

naudio using pull model here. waveout going demanded samples sound card going call upstream myfilter.read(), in turn going call audiofilereader.read().

if want add gain either create new isampleprovider following same pattern or inline low pass filter's read function:

public int read(float[] buffer, int offset, int count) {     int samplesread = sourceprovider.read(buffer, offset, count);      (int = 0; < samplesread; i++)         buffer[offset + i] = gain * filters[(i % channels)].transform(buffer[offset + i]);         //                   ^^^^      return samplesread; }