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Diffstat (limited to 'examples/power.c')
| -rw-r--r-- | examples/power.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/examples/power.c b/examples/power.c new file mode 100644 index 0000000..01bfe5d --- /dev/null +++ b/examples/power.c @@ -0,0 +1,220 @@ +/* + This program is derived from Chris Vaill's normalize program + and has been modified to use the Audio File Library for file + reading and audio data conversion. + + Copyright (C) 2001, Silicon Graphics, Inc. + Copyright (C) 1999-2001, Chris Vaill + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2 of + the License, or (at your option) any later version. + + This program is distributed in the hope that it will be + useful, but WITHOUT ANY WARRANTY; without even the implied + warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR + PURPOSE. See the GNU General Public License for more details. + + You should have received a copy of the GNU General Public + License along with this program; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, + MA 02111-1307, USA. +*/ + +/* + power.c + + Calculate the power and peak amplitudes of an audio file. +*/ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#include <audiofile.h> + +#ifndef TRUE +#define TRUE 1 +#endif + +#ifndef FALSE +#define FALSE 0 +#endif + +struct smooth +{ + double *buf; + int length, start, n; +}; + +static double get_smoothed_data (struct smooth *s) +{ + int i; + double smoothed; + + smoothed = 0; + for (i = 0; i < s->n; i++) + smoothed += s->buf[i]; + smoothed = smoothed / s->n; + + return smoothed; +} + +void print_power (char *filename); + +int main (int argc, char **argv) +{ + int i; + + if (argc < 2) + { + fprintf(stderr, "usage: %s filename [more filenames...]\n", + argv[0]); + exit(EXIT_FAILURE); + } + + for (i=1; i<argc; i++) + print_power(argv[i]); + + return 0; +} + +void print_power (char *filename) +{ + AFfilehandle file; + double *sums, *frames; + int channelCount, windowSize, frameCount; + int i, c; + struct smooth *powsmooth; + int winStart, winEnd; + int lastWindow = FALSE; + double pow, maxpow; + + double level, peak, minSample = 1, maxSample = -1; + + file = afOpenFile(filename, "r", NULL); + if (file == AF_NULL_FILEHANDLE) + { + fprintf(stderr, "Could not open file %s.\n", filename); + return; + } + + channelCount = afGetChannels(file, AF_DEFAULT_TRACK); + windowSize = afGetRate(file, AF_DEFAULT_TRACK) / 100; + frameCount = afGetFrameCount(file, AF_DEFAULT_TRACK); + + sums = calloc(channelCount, sizeof (double)); + for (c=0; c<channelCount; c++) + sums[c] = 0; + + frames = calloc(channelCount * windowSize, sizeof (double)); + + afSetVirtualSampleFormat(file, AF_DEFAULT_TRACK, AF_SAMPFMT_DOUBLE, + sizeof (double)); + + powsmooth = calloc(channelCount, sizeof (struct smooth)); + for (c=0; c<channelCount; c++) + { + /* Use a 100-element (1 second) window. */ + powsmooth[c].length = 100; + powsmooth[c].buf = calloc(powsmooth[c].length, sizeof (double)); + powsmooth[c].start = 0; + powsmooth[c].n = 0; + } + + winStart = 0; + winEnd = 0; + lastWindow = FALSE; + maxpow = 0; + + do + { + winEnd = winStart + windowSize; + + if (winEnd >= frameCount) + { + winEnd = frameCount; + lastWindow = TRUE; + } + + afReadFrames(file, AF_DEFAULT_TRACK, frames, windowSize); + + for (c=0; c<channelCount; c++) + { + sums[c] = 0; + + for (i=0; i < winEnd - winStart; i++) + { + double sample; + + sample = frames[i*channelCount + c]; + sums[c] += sample*sample; + + if (sample > maxSample) + maxSample = sample; + if (sample < minSample) + minSample = sample; + } + } + + /* Compute power for each channel. */ + for (c=0; c<channelCount; c++) + { + double pow; + int end; + + pow = sums[c] / (winEnd - winStart); + + end = (powsmooth[c].start + powsmooth[c].n) % + powsmooth[c].length; + powsmooth[c].buf[end] = pow; + + if (powsmooth[c].n == powsmooth[c].length) + { + powsmooth[c].start = (powsmooth[c].start + 1) % powsmooth[c].length; + pow = get_smoothed_data(&powsmooth[c]); + if (pow > maxpow) + maxpow = pow; + } + else + { + powsmooth[c].n++; + } + } + + winStart += windowSize; + } while (!lastWindow); + + for (c = 0; c < channelCount; c++) + { + pow = get_smoothed_data(&powsmooth[c]); + if (pow > maxpow) + maxpow = pow; + } + + free(sums); + free(frames); + for (c=0; c<channelCount; c++) + free(powsmooth[c].buf); + free(powsmooth); + + level = sqrt(maxpow); + + afCloseFile(file); + + printf("file: %s\n", filename); + + printf("level (dB): %f\n", 20 * log10(level)); + printf("peak-: %f\n", minSample); + printf("peak+: %f\n", maxSample); + + peak = abs(minSample); + if (peak < abs(maxSample)) + peak = abs(maxSample); + + printf("peak (dB): %f\n", 20 * log10(peak)); +} |