naudio - Record audio from microphone and speaker in C# -

i'm building application record audio microphone , speaker file (.wav). want application write data file microphone , speaker same merged file. i'm having trouble save merged file both. saves microphone.

this code:

using naudio.wave; using system; using system.collections.generic; using system.componentmodel; using system.data; using system.drawing; using system.linq; using system.text; using system.windows.forms;  namespace test_recorder {     public partial class form2 : form     {         private wavein recorder;         private bufferedwaveprovider bufferedwaveprovider;         private savingwaveprovider savingwaveprovider;         private waveout player;         public form2()         {             initializecomponent();         }          private void button1_click(object sender, eventargs e)         {             startrecording();         }          private void button2_click(object sender, eventargs e)         {             stoprecording();         }         public void startrecording()         {             // set recorder             recorder = new wavein();             //recorder = new wasapiloopbackcapture();             //recorder = new wavein();             recorder.dataavailable += recorderondataavailable;              // set our signal chain             bufferedwaveprovider = new bufferedwaveprovider(recorder.waveformat);             savingwaveprovider = new savingwaveprovider(bufferedwaveprovider, guid.newguid() + ".wav");              // set playback             player = new waveout();             player.init(savingwaveprovider);             player.volume = 1;             // begin playback & record             player.play();             recorder.startrecording();         }         public void stoprecording()         {             // stop recording             recorder.stoprecording();             // stop playback             player.stop();             // finalise wav file             savingwaveprovider.dispose();         }         private void recorderondataavailable(object sender, waveineventargs waveineventargs)         {             bufferedwaveprovider.addsamples(waveineventargs.buffer, 0, waveineventargs.bytesrecorded);         }          private void button3_click(object sender, eventargs e)         {             //rec.beginrecording();             form3 frm = new form3();             this.hide();             frm.show();         }     }       class savingwaveprovider : iwaveprovider, idisposable     {         private readonly iwaveprovider sourcewaveprovider;         private readonly wavefilewriter writer;         private bool iswriterdisposed;          public savingwaveprovider(iwaveprovider sourcewaveprovider, string wavfilepath)         {             this.sourcewaveprovider = sourcewaveprovider;             writer = new wavefilewriter(wavfilepath, sourcewaveprovider.waveformat);         }          public int read(byte[] buffer, int offset, int count)         {             var read = sourcewaveprovider.read(buffer, offset, count);             if (count > 0 && !iswriterdisposed)             {                 writer.write(buffer, offset, read);             }             if (count == 0)             {                 dispose(); // auto-dispose in case users forget             }             return read;         }          public waveformat waveformat { { return sourcewaveprovider.waveformat; } }          public void dispose()         {             if (!iswriterdisposed)             {                 iswriterdisposed = true;                 writer.dispose();             }         }     } } 

how can both speaker , microphone same file?

probably easiest approach save both separate files, , use mixingsampleprovider mix them after recording. easiest if both recorded in same wave format (sample rate, bit depth, channel count).