first commit

.gitignore

@@ -0,0 +1,3 @@
+*.o
+*.wav
+/conv

Makefile

@@ -0,0 +1,10 @@
+CFLAGS=   -Wfatal-errors $(shell pkgconf --cflags portaudio-2.0)
+LDFLAGS=  -s $(shell pkgconf --libs portaudio-2.0)
+
+all: conv
+conv: main.o
+	$(CC) $^ -o $@ $(LDFLAGS)
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+clean:
+	$(RM) conv *.o

main.c

@@ -0,0 +1,143 @@
+#include<portaudio.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<math.h>
+#include<stdint.h>
+#include<unistd.h>
+#include<fcntl.h>
+#include<string.h>
+
+// Open .WAV file, read into buffer
+// assuming samplerate, bitdepth, and
+// channels
+void op(const char*fn,float*buf,int len)
+{
+	int fd;
+	int16_t tmpbuf[len];
+	if(!fn||!buf||!len)return;
+
+	fd=open(fn,O_RDONLY);
+	if(fd<0)
+	{
+		write(1,"fail\n",5);
+		return;
+	}
+
+	// Skip WAVE header (assume 44.1kHz
+	// samplerate, mono channels, and 16bit
+	lseek(fd,40,SEEK_SET);
+
+	// Read file into buffer and convert from
+	// int16_t to float
+	read(fd,tmpbuf,len*sizeof(int16_t));
+	for(int i=0;i<len;++i)
+		buf[i]=((float)tmpbuf[i])/(float)INT16_MAX;
+
+	close(fd);
+}
+
+// Low-pass convolving filter
+void lp(float*cur,float*prev,float*next,int len,int winsz)
+{
+	if(!cur||!prev||!next||!len||!winsz)return;
+	for(int i=0,k;i<len;++i)
+	{
+		float sum=0;
+		k=i-winsz/2;
+		for(int j=0;j<winsz;++j,++k)
+		{
+			if(k<0)
+				sum+=prev[k+len];
+			else if(k>=len)
+				sum+=next[k%len];
+			else
+				sum+=cur[k];
+		}
+		cur[i]=sum/winsz;
+	}
+}
+
+// Sine oscillator
+void sn(float*d,int len,int cycle,int*offset)
+{
+	for(int j=0,cycle=44100/440;j<len;++j,*offset=(*offset+1)%cycle)
+		d[j]=sin(2.0*M_PI*((float)*offset)/cycle)*0.25;
+}
+
+// Saw-tooth oscillator
+void sw(float*d,int len,int cycle,int*offset)
+{
+	*offset%=cycle;
+	for(int j=0,cycle=44100/440;j<len;++j,*offset=(*offset+1)%cycle)
+		d[j]=((float)*offset)/cycle*0.25;
+}
+
+
+
+#define swapbuffers() do{float*tmp=prev;prev=cur;cur=next;next=tmp;}while(0)
+
+int main(void)
+{
+	PaStream*pa;
+	const int len=1024;
+	float buffer1[len];
+	float buffer2[len];
+	float buffer3[len];
+	float wave[44100];
+	float*cur=buffer2,*next=buffer3,*prev=buffer1;
+	int envsize=400;
+	int offset=0;
+	int wave_or_osc=0;
+
+	if(envsize>len)envsize=len;
+
+	// Init portaudio
+	Pa_Initialize();
+	Pa_OpenDefaultStream(&pa,0,1,paFloat32,44100,len,NULL,NULL);
+	Pa_StartStream(pa);
+
+	// Read wave file into buffer
+	op("w.wav",wave,44100);
+
+	// Generate initial buffer
+	if(wave_or_osc==0)
+		sw(next,len,44100/440,&offset);
+	else
+	{
+		memcpy(next,wave+offset,len*sizeof(float));
+		offset+=len;
+	}
+
+	// Play dynamic audio
+	for(int i=0,last=44100/len/2;i<last;++i)
+	{
+		swapbuffers();
+
+		// Oscillator
+		if(wave_or_osc==0)
+			sw(next,len,44100/440,&offset);
+		else
+		{
+			memcpy(next,wave+offset,len*sizeof(float));
+			offset+=len;
+		}
+
+		// Filter
+		lp(cur,prev,next,len,44100/1000);
+
+		// Amplitude envelope
+		if(i==0)
+			for(int j=0;j<envsize;++j)
+				cur[j]*=((float)j)/envsize;
+		else if(i==last-1)
+			for(int j=0;j<envsize;++j)
+				cur[len-j]*=((float)j)/envsize;
+
+		Pa_WriteStream(pa,cur,len);
+	}
+	Pa_Sleep(800);
+
+	// Quit
+	Pa_CloseStream(pa);
+	Pa_Terminate();
+}