I have this question, which can also be found at
http://stackoverflow.com/questions/17744053/noise-cancellation-setup-combining-the-microphones-signals-intelligently.
There you can also find more detail information + pictures.
Maybe it's interesting for you and you can help.
I built a noise cancellation setup with two microphones and two
different microphone preamplifiers that go to two different channels of
a stereo recording.
Here is a sample I'd use as "Datei"
http://filestore.to/?d=U5FN2IH96K
I tried
/static void *voneinanderabziehen( char *Datei)//
//{//
// char ergebnis[80]; //
// sprintf(ergebnis,"%s.neu.raw",Datei);//
// FILE* ausgabe = fopen(ergebnis, "wb");//
// FILE* f = fopen(Datei, "rb"); //
// if (f == NULL)//
// return;//
// int i = -1;//
// int r1 = 0;//
// int r2 = 0;//
// int l1 = 0;//
// int l2 = 0;//
// int zaehler = 0;//
// int l = 0;//
// int r = 0;//
// int wo = 0;//
// int dif = 0;//
// float g = 0.1;//
// float RC = 1.0/(1215*2*3.14);//
// float dt = 1.0/44100;//
// float alpha = dt/(RC+dt);//
// float beginn = 0;//
// float vorher = 0;//
// int jetzt = 0;//
////
// while(wo !=EOF)//
// {//
// wo = getc(f);//
// if (zaehler == 0)//
// beginn = wo;//
// zaehler++;//
////
// } //
//// printf("zaehler: %d\n",zaehler); //
// wo = 0;//
// rewind(f); //
//// printf("zurückgedreht\n");//
////
// vorher = beginn;//
// zaehler = 1; //
////
// while(wo !=EOF)//
// {//
// wo = getc(f); //
// i++;//
// if (i == 0)//
// r1 = (unsigned)wo;//
// if (i == 1)//
// {//
// r2 = (unsigned)wo;//
// r = (r2<<8)+r1; //r1 | r2 << 8; //
// }//
// if (i == 2)//
// l1 = (unsigned)wo;//
// if (i == 3)//
// {//
// l2 = (unsigned)wo;//
// l = (l2<<8)+l1; //l1 | l2 << 8; //
// //dif = r - (l*2);//
////
// jetzt = vorher + (alpha*(l - vorher));//
// dif = r - g*jetzt;//
// vorher = jetzt; //
// zaehler++;//
// if (dif != 0)//
// {//
// putc((char) ( (unsigned)dif & 0xff),ausgabe);//
// putc((char) (((unsigned)dif >> 8) & 0xff),ausgabe);//
// } //
// i = -1;//
// }//
// } //
// fclose(f);//
// fclose(ausgabe); //
// char output[300]; //
// sprintf(output,"rm -frv \"%s\"",Datei);//
// system(output);//
//}//
/
Which creates moderately distorted sound until I set g to 0. Using 1 for
g creates highly distorted sound.
l = left channel
r = right Channel
I am reading in the wave raw file Datei in a binary way.
jetzt = vorher + (alpha*(l - vorher)); is a low pass filter.
If you have questions, please refer to the thread mentioned. If you have
questions beyond the replies there I am happy to answer them here or there.
While we are at it, how do I normalize the final mono output to make it
as loud as possible without clipping, ie what's the highest/lowest value?
Best
Alexander
_______________________________________________
pulseaudio-discuss mailing list
[email protected]
http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
