/* t48_8.c David Rowe May 10 2012 Unit test for 48 to 8 kHz sample rate conversion functions. I evaluated output by plotting using Octave and looking for jaggies: pl("../unittest/out48.raw",1,3000) pl("../unittest/out8.raw",1,3000) Listening to it also shows up anything nasty: $ play -s -2 -r 48000 out48.raw $ play -s -2 -r 8000 out8.raw */ #include <assert.h> #include <math.h> #include <stdlib.h> #include <stdio.h> #include "fdmdv.h" #define N8 160 /* procssing buffer size at 8 kHz */ #define N48 (N8*FDMDV_OS) #define MEM8 (FDMDV_OS_TAPS/FDMDV_OS) #define FRAMES 50 #define TWO_PI 6.283185307 #define FS 8000 #define SINE int main() { float in8k[MEM8 + N8]; float out48k[N48]; short out48k_short[N48]; FILE *f48; float in48k[FDMDV_OS_TAPS + N48]; float out8k[N48]; short out8k_short[N8]; FILE *f8; int i,f,t,t1; float freq = 800.0; f48 = fopen("out48.raw", "wb"); assert(f48 != NULL); f8 = fopen("out8.raw", "wb"); assert(f8 != NULL); /* clear filter memories */ for(i=0; i<MEM8; i++) in8k[i] = 0.0; for(i=0; i<FDMDV_OS_TAPS; i++) in48k[i] = 0.0; t = t1 = 0; for(f=0; f<FRAMES; f++) { #ifdef DC for(i=0; i<N8; i++) in8k[MEM8+i] = 16000.0; #endif #ifdef SINE for(i=0; i<N8; i++,t++) in8k[MEM8+i] = 16000.0*cos(TWO_PI*t*freq/FS); #endif /* upsample */ fdmdv_8_to_48(out48k, &in8k[MEM8], N8); /* for(i=0; i<MEM8; i++) in8k[i] = in8k[i+N8]; */ /* save 48k to disk for plotting and check out */ for(i=0; i<N48; i++) out48k_short[i] = (short)out48k[i]; fwrite(out48k_short, sizeof(short), N48, f48); /* add a 10 kHz spurious signal for fun, we want down sampler to knock this out */ for(i=0; i<N48; i++,t1++) in48k[i+FDMDV_OS_TAPS] = out48k[i] + 16000.0*cos(TWO_PI*t1*1E4/FS); /* downsample */ fdmdv_48_to_8(out8k, &in48k[FDMDV_OS_TAPS], N8); /* for(i=0; i<FDMDV_OS_TAPS; i++) in48k[i] = in48k[i+N48]; */ /* save 8k to disk for plotting and check out */ for(i=0; i<N8; i++) out8k_short[i] = (short)out8k[i]; fwrite(out8k_short, sizeof(short), N8, f8); } fclose(f48); fclose(f8); return 0; }