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76 lines
1.7 KiB
76 lines
1.7 KiB
#define _USE_MATH_DEFINES
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#include<stdio.h>
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#include<math.h>
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#include<stdlib.h>
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#define LENGTH 512 /* 信号長N ただし，2の整数乗 */
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/* プロトタイプ宣言 */
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double calcAmpPower(short *x, int N);
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void applyWindow(short *x, int N);
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int main(int argc, char *argv[]) {
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/* 信号長 */
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int N = LENGTH;
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double beforePower, afterPower;
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int i;
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FILE *fp = NULL;
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if (argc > 1) {
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fp = fopen(argv[1], "rb");
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if (fp == NULL) {
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fprintf(stderr, "File open error (%s)\n", argv[1]);
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exit(1);
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}
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} else {
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fprintf(stderr, "Usage: %s input-filename\n", argv[0]);
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exit(1);
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}
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/* 入力信号配列 */
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short input[LENGTH];
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/* 音声データを読み込み */
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if (fread(input, sizeof(short), N, fp) != (size_t)N) {
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fprintf(stderr, "File read error (%s)\n", argv[1]);
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fclose(fp);
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exit(1);
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}
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beforePower = calcAmpPower(input, N);
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applyWindow(input, N);
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afterPower = calcAmpPower(input, N);
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printf("BEFORE : %16f\n", beforePower);
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printf("AFTER : %16f\n", afterPower);
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printf("DIFF : %16f\n", beforePower - afterPower);
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printf("RATIO : %16f\n", afterPower / beforePower);
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fclose(fp);
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return 0;
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}
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/* short型配列の平均パワーを求める関数 */
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double calcAmpPower(short *x, int N) {
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double amp;
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double power = 0.0;
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for (int i = 0; i < N; i++) {
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amp = x[i] * x[i];
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power += amp;
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}
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return power / N;
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}
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/* 配列にハニング窓を適用 */
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void applyWindow(short *x, int N) {
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for (int i = 0; i < N; i++) {
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double w = 0.5 - 0.5 * cos(2 * M_PI * i / (N - 1)); // ハニング窓
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x[i] *= w;
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}
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} |