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https://github.com/FFmpeg/FFmpeg.git
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b3ec5b00ce
This avoids unneeded computations Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
111 lines
3.3 KiB
C
111 lines
3.3 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <inttypes.h>
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#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
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#define FFMAX(a,b) ((a) > (b) ? (a) : (b))
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static int64_t fsize(FILE *f){
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int64_t end, pos= ftell(f);
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fseek(f, 0, SEEK_END);
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end = ftell(f);
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fseek(f, pos, SEEK_SET);
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return end;
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}
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int main(int argc, char **argv){
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FILE *f[2];
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int i, pos;
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int siglen, datlen;
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int bestpos;
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double bestc=0;
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double sigamp= 0;
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int16_t *signal, *data;
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int maxshift= 16384;
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if (argc < 3) {
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printf("audiomatch <testfile> <reffile>\n");
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printf("WAV headers are skipped automatically.\n");
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return 1;
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}
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f[0] = fopen(argv[1], "rb");
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f[1] = fopen(argv[2], "rb");
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if (!f[0] || !f[1]) {
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fprintf(stderr, "Could not open input files.\n");
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return 1;
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}
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for (i = 0; i < 2; i++) {
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uint8_t p[100];
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if (fread(p, 1, 12, f[i]) != 12)
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return 1;
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if (!memcmp(p, "RIFF", 4) &&
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!memcmp(p + 8, "WAVE", 4)) {
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if (fread(p, 1, 8, f[i]) != 8)
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return 1;
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while (memcmp(p, "data", 4)) {
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int s = p[4] | p[5] << 8 | p[6] << 16 | p[7] << 24;
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fseek(f[i], s, SEEK_CUR);
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if (fread(p, 1, 8, f[i]) != 8)
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return 1;
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}
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} else {
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fseek(f[i], -12, SEEK_CUR);
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}
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}
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datlen = fsize(f[0]) - ftell(f[0]);
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siglen = fsize(f[1]) - ftell(f[1]);
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data = malloc(datlen * sizeof(*data));
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signal = malloc(siglen * sizeof(*signal));
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fread(data , 1, datlen, f[0]);
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fread(signal, 1, siglen, f[1]);
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datlen /= 2;
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siglen /= 2;
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for(i=0; i<siglen; i++){
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signal[i] = ((uint8_t*)(signal + i))[0] + 256*((uint8_t*)(signal + i))[1];
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sigamp += signal[i] * signal[i];
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}
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for(i=0; i<datlen; i++)
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data[i] = ((uint8_t*)(data + i))[0] + 256*((uint8_t*)(data + i))[1];
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for(pos = 0; pos<maxshift; pos = pos < 0 ? -pos: -pos-1){
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int64_t c= 0;
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int testlen = FFMIN(siglen, datlen-pos);
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for(i=FFMAX(0, -pos); i<testlen; i++){
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int j= pos+i;
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c += signal[i] * data[j];
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}
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if(fabs(c) > sigamp * 0.94)
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maxshift = FFMIN(maxshift, fabs(pos)+32);
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if(fabs(c)>fabs(bestc)){
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bestc= c;
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bestpos = pos;
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}
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}
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printf("presig: %d postsig:%d c:%7.4f lenerr:%d\n", bestpos, datlen - siglen - bestpos, bestc / sigamp, datlen - siglen);
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}
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