mirror of
https://github.com/cookiengineer/audacity
synced 2025-11-03 23:53:55 +01:00
254 lines
7.7 KiB
C
254 lines
7.7 KiB
C
/*
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* TwoLAME: an optimized MPEG Audio Layer Two encoder
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*
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* Copyright (C) 2001-2004 Michael Cheng
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* Copyright (C) 2004-2006 The TwoLAME Project
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*
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* This library 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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* This library 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 this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* $Id$
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*
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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 "audio_wave.h"
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/*****************************************************************************
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*
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* Routines to determine byte order (of this machine) and swap bytes
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*
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*****************************************************************************/
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enum byte_order { order_unknown, order_bigEndian, order_littleEndian };
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static enum byte_order DetermineByteOrder(void)
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{
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char s[sizeof(long) + 1];
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union {
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long longval;
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char charval[sizeof(long)];
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} probe;
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probe.longval = 0x41424344L; /* ABCD in ASCII */
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strncpy(s, probe.charval, sizeof(long));
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s[sizeof(long)] = '\0';
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/* printf("byte order is %s\n", s ); */
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if (strcmp(s, "ABCD") == 0)
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return order_bigEndian;
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else if (strcmp(s, "DCBA") == 0)
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return order_littleEndian;
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else
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return order_unknown;
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}
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static void SwapBytesInWords(short *loc, int words)
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{
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int i;
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short thisval;
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char *dst, *src;
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src = (char *) &thisval;
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for (i = 0; i < words; i++) {
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thisval = *loc;
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dst = (char *) loc++;
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dst[0] = src[1];
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dst[1] = src[0];
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}
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}
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/*****************************************************************************
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*
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* Read in specified number of samples
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*
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*****************************************************************************/
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int wave_get_samples(wave_info_t * wave_info, short int pcm[], int numSamples)
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{
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int samples_read;
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FILE *file = wave_info->soundfile;
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samples_read = fread(pcm, sizeof(short int), numSamples, file);
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if (wave_info->byteswap) {
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SwapBytesInWords(pcm, samples_read);
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}
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return (samples_read / wave_info->channels);
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}
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/*****************************************************************************
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*
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* parse the wave header.
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* returns NULL if not open failed
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* returns a wave_info_t * if wave header successfully parsed.
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* needs to fill in : samplerate + channels
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*
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* POST: wave_info->soundfile is set to be at the start of the
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* PCM audio data
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*
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*****************************************************************************/
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wave_info_t *wave_init(char *inPath)
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{
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unsigned char wave_header_buffer[40]; // HH fixed
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int wave_header_read = 0;
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int wave_header_stereo = -1;
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int wave_header_16bit = -1;
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unsigned long samplerate;
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enum byte_order NativeByteOrder = order_unknown;
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wave_info_t *wave_info = NULL;
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FILE *file;
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if ((file = fopen(inPath, "rb")) == NULL) {
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printf("WAV: cannot open input file: %s\n", inPath);
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return (NULL);
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}
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/************** WAVE ************************/
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/* Nick Burch <The_Leveller@newmail.net> */
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/********************************************/
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/* Wave File Headers: (Dec) */
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/* 8-11 = "WAVE" */
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/* 22 = Stereo / Mono */
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/* 01 = mono, 02 = stereo */
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/* 24 = Sampling Frequency */
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/* 32 = Data Rate */
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/* 01 = x1 (8bit Mono) */
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/* 02 = x2 (8bit Stereo or */
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/* 16bit Mono) */
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/* 04 = x4 (16bit Stereo) */
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/********************************************/
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fseek(file, 0, SEEK_SET);
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fread(wave_header_buffer, 1, 40, file);
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if (wave_header_buffer[8] == 'W' && wave_header_buffer[9] == 'A'
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&& wave_header_buffer[10] == 'V' && wave_header_buffer[11] == 'E') {
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printf("Parsing Wave File Header\n");
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if (NativeByteOrder == order_unknown) {
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NativeByteOrder = DetermineByteOrder();
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if (NativeByteOrder == order_unknown) {
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printf("byte order not determined\n");
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fclose(file);
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return (NULL);
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}
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}
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if (NativeByteOrder == order_littleEndian) {
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samplerate = *(unsigned long *) (&wave_header_buffer[24]);
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} else {
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samplerate = wave_header_buffer[27] +
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(wave_header_buffer[26] << 8) +
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(wave_header_buffer[25] << 16) + (wave_header_buffer[24] << 24);
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}
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/* Wave File */
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wave_header_read = 1;
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switch (samplerate) {
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case 44100:
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case 48000:
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case 32000:
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case 24000:
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case 22050:
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case 16000:
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printf(">>> %ld Hz sampling freq selected\n", samplerate);
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break;
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default:
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/* Unknown Unsupported Frequency */
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printf(">>> Unknown samp freq %ld Hz in Wave Header\n", samplerate);
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printf(">>> Default 44.1 kHz samp freq selected\n");
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samplerate = 44100;
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break;
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}
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if ((long) wave_header_buffer[22] == 1) {
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printf(">>> Input Wave File is Mono\n");
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wave_header_stereo = 0;
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}
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if ((long) wave_header_buffer[22] == 2) {
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printf(">>> Input Wave File is Stereo\n");
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wave_header_stereo = 1;
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}
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if ((long) wave_header_buffer[32] == 1) {
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printf(">>> Input Wave File is 8 Bit\n");
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wave_header_16bit = 0;
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printf("Input File must be 16 Bit! Please Re-sample");
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fclose(file);
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return (NULL);
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}
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if ((long) wave_header_buffer[32] == 2) {
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if (wave_header_stereo == 1) {
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printf(">>> Input Wave File is 8 Bit\n");
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wave_header_16bit = 0;
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printf("Input File must be 16 Bit! Please Re-sample");
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fclose(file);
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return (NULL);
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} else {
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/* printf(">>> Input Wave File is 16 Bit\n" ); */
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wave_header_16bit = 1;
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}
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}
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if ((long) wave_header_buffer[32] == 4) {
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/* printf(">>> Input Wave File is 16 Bit\n" ); */
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wave_header_16bit = 1;
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}
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/* should probably use the wave header to determine size here FIXME MFC Feb 2003 */
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if (fseek(file, 44, SEEK_SET) != 0) {
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/* there's a way of calculating the size of the wave header. i'll just jump 44 to start
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with */
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printf("Could not seek to PCM sound data in \"%s\".\n", inPath);
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fclose(file);
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return (NULL);
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}
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// Successfully processed the wave header
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wave_info = (wave_info_t *) calloc(1, sizeof(wave_info_t));
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wave_info->soundfile = file;
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if (wave_header_stereo == 1)
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wave_info->channels = 2;
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else
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wave_info->channels = 1;
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wave_info->samplerate = samplerate;
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// UNKNOWN. But we really should be able to work
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// it out. FIX THIS. MFC May03.
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wave_info->num_samples = -1;
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// Enable byte swap for big endian machines
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if (NativeByteOrder == order_bigEndian)
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wave_info->byteswap = 1;
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else
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wave_info->byteswap = 0;
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return (wave_info);
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}
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// not a wave file
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fclose(file);
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return (NULL);
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}
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/* vim:ts=4:sw=4:nowrap: */
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