// Dot product (Convolution) float output = 0; for (int i = 0; i < COEFFS; i++) { output += b[i] * history[i]; } return output; }
printf("Digital Media Processing - FIR Filter Demo\n"); for(int i = 0; i < len; i++) { float filtered = process_audio_sample(noisy_audio[i]); printf("In: %5.2f -> Out: %5.2f\n", noisy_audio[i], filtered); } return 0; }
y[n] = b0*x[n] + b1*x[n-1] + a1*y[n-1]
int main() { // Simulated audio buffer (static noise) float noisy_audio[] = {1.0, -0.5, 0.8, -0.2, 0.6}; int len = sizeof(noisy_audio) / sizeof(noisy_audio[0]);
#include <stdio.h> #include <stdint.h> // Co-efficients for a Low Pass Filter (Normalized) #define COEFFS 3 static const float b[COEFFS] = {0.25, 0.5, 0.25}; // Triangular smoothing static float history[COEFFS] = {0, 0, 0}; digital media processing dsp algorithms using c pdf
float process_audio_sample(float input_sample) { // Shift the history buffer (C implementation trick: move pointers instead of data if performance matters) for (int i = COEFFS - 1; i > 0; i--) { history[i] = history[i-1]; } history[0] = input_sample;
static float x_1 = 0, y_1 = 0; float process_filter(float input) { float output = b0 * input + b1 * x_1 + a1 * y_1; x_1 = input; y_1 = output; return output; } A purely floating-point PDF is a "study guide," not an engineering manual. A great PDF will show the conversion: // Dot product (Convolution) float output = 0;
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