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wave.c
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wave.c
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/* Sonic library
Copyright 2010
Bill Cox
This file is part of the Sonic Library.
This file is licensed under the Apache 2.0 license.
*/
/*
This file supports read/write wave files.
*/
#include "wave.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define WAVE_BUF_LEN 4096
struct waveFileStruct {
int numChannels;
int sampleRate;
FILE* soundFile;
int bytesWritten; /* The number of bytes written so far, including header */
int failed;
int isInput;
};
/* Write a string to a file. */
static void writeBytes(waveFile file, void* bytes, int length) {
size_t bytesWritten;
if (file->failed) {
return;
}
bytesWritten = fwrite(bytes, sizeof(char), length, file->soundFile);
if (bytesWritten != length) {
fprintf(stderr, "Unable to write to output file");
file->failed = 1;
}
file->bytesWritten += bytesWritten;
}
/* Write a string to a file. */
static void writeString(waveFile file, char* string) {
writeBytes(file, string, strlen(string));
}
/* Write an integer to a file in little endian order. */
static void writeInt(waveFile file, int value) {
char bytes[4];
int i;
for (i = 0; i < 4; i++) {
bytes[i] = value;
value >>= 8;
}
writeBytes(file, bytes, 4);
}
/* Write a short integer to a file in little endian order. */
static void writeShort(waveFile file, short value) {
char bytes[2];
int i;
for (i = 0; i < 2; i++) {
bytes[i] = value;
value >>= 8;
}
writeBytes(file, bytes, 2);
}
/* Read bytes from the input file. Return the number of bytes actually read. */
static int readBytes(waveFile file, void* bytes, int length) {
if (file->failed) {
return 0;
}
return fread(bytes, sizeof(char), length, file->soundFile);
}
/* Read an exact number of bytes from the input file. */
static void readExactBytes(waveFile file, void* bytes, int length) {
int numRead;
if (file->failed) {
return;
}
numRead = fread(bytes, sizeof(char), length, file->soundFile);
if (numRead != length) {
fprintf(stderr, "Failed to read requested bytes from input file\n");
file->failed = 1;
}
}
/* Read an integer from the input file */
static int readInt(waveFile file) {
unsigned char bytes[4];
int value = 0, i;
readExactBytes(file, bytes, 4);
for (i = 3; i >= 0; i--) {
value <<= 8;
value |= bytes[i];
}
return value;
}
/* Read a short from the input file */
static int readShort(waveFile file) {
unsigned char bytes[2];
int value = 0, i;
readExactBytes(file, bytes, 2);
for (i = 1; i >= 0; i--) {
value <<= 8;
value |= bytes[i];
}
return value;
}
/* Read a string from the input and compare it to an expected string. */
static void expectString(waveFile file, char* expectedString) {
char buf[11]; /* Be sure that we never call with a longer string */
int length = strlen(expectedString);
if (length > 10) {
fprintf(stderr, "Internal error: expected string too long\n");
file->failed = 1;
} else {
readExactBytes(file, buf, length);
buf[length] = '\0';
if (strcmp(expectedString, buf)) {
fprintf(stderr, "Unsupported wave file format: Expected '%s', got '%s;\n",
expectedString, buf);
file->failed = 1;
}
}
}
/* Write the header of the wave file. */
static void writeHeader(waveFile file, int sampleRate, int numChannels) {
/* write the wav file per the wav file format */
writeString(file, "RIFF"); /* 00 - RIFF */
/* We have to fseek and overwrite this later when we close the file because */
/* we don't know how big it is until then. */
writeInt(file,
36 /* + dataLength */); /* 04 - how big is the rest of this file? */
writeString(file, "WAVE"); /* 08 - WAVE */
writeString(file, "fmt "); /* 12 - fmt */
writeInt(file, 16); /* 16 - size of this chunk */
writeShort(
file,
1); /* 20 - what is the audio format? 1 for PCM = Pulse Code Modulation */
writeShort(file,
numChannels); /* 22 - mono or stereo? 1 or 2? (or 5 or ???) */
writeInt(file, sampleRate); /* 24 - samples per second (numbers per second) */
writeInt(file, sampleRate * 2); /* 28 - bytes per second */
writeShort(file, 2); /* 32 - # of bytes in one sample, for all channels */
writeShort(
file, 16); /* 34 - how many bits in a sample(number)? usually 16 or 24 */
writeString(file, "data"); /* 36 - data */
writeInt(file, 0); /* 40 - how big is this data chunk */
}
/* Read the header of the wave file. */
static int readHeader(waveFile file) {
int data;
expectString(file, "RIFF");
data = readInt(file); /* 04 - how big is the rest of this file? */
expectString(file, "WAVE"); /* 08 - WAVE */
expectString(file, "fmt "); /* 12 - fmt */
int chunkSize = readInt(file); /* 16 or 18 - size of this chunk */
if (chunkSize != 16 && chunkSize != 18) {
fprintf(stderr, "Only basic wave files are supported\n");
return 0;
}
data = readShort(file); /* 20 - what is the audio format? 1 for PCM = Pulse
Code Modulation */
if (data != 1) {
fprintf(stderr, "Only PCM wave files are supported (not %d)\n", data);
return 0;
}
file->numChannels =
readShort(file); /* 22 - mono or stereo? 1 or 2? (or 5 or ???) */
file->sampleRate =
readInt(file); /* 24 - samples per second (numbers per second) */
readInt(file); /* 28 - bytes per second */
readShort(file); /* 32 - # of bytes in one sample, for all channels */
data = readShort(
file); /* 34 - how many bits in a sample(number)? usually 16 or 24 */
if (data != 16) {
fprintf(stderr, "Only 16 bit PCM wave files are supported\n");
return 0;
}
if (chunkSize == 18) { /* ffmpeg writes 18, and so has 2 extra bytes here */
data = readShort(file);
}
/* Read and discard chunks until we find the "data" chunk or fail */
char chunk[5];
chunk[4] = 0;
while (1) {
readExactBytes(file, chunk, 4); /* chunk id */
int size = readInt(file); /* how big is this data chunk */
if (strcmp(chunk, "data") == 0) {
return 1;
}
if (fseek(file->soundFile, size, SEEK_CUR) != 0) {
fprintf(stderr, "Failed to seek on input file.\n");
return 0;
}
}
}
/* Close the input or output file and free the waveFile. */
static void closeFile(waveFile file) {
FILE* soundFile = file->soundFile;
if (soundFile != NULL) {
fclose(soundFile);
file->soundFile = NULL;
}
free(file);
}
/* Open a 16-bit little-endian wav file for reading. It may be mono or stereo.
*/
waveFile openInputWaveFile(const char* fileName, int* sampleRate, int* numChannels) {
waveFile file;
FILE* soundFile = fopen(fileName, "rb");
if (soundFile == NULL) {
fprintf(stderr, "Unable to open wave file %s for reading\n", fileName);
return NULL;
}
file = (waveFile)calloc(1, sizeof(struct waveFileStruct));
file->soundFile = soundFile;
file->isInput = 1;
if (!readHeader(file)) {
closeFile(file);
return NULL;
}
*sampleRate = file->sampleRate;
*numChannels = file->numChannels;
return file;
}
/* Open a 16-bit little-endian wav file for writing. It may be mono or stereo.
*/
waveFile openOutputWaveFile(const char* fileName, int sampleRate, int numChannels) {
waveFile file;
FILE* soundFile = fopen(fileName, "wb");
if (soundFile == NULL) {
fprintf(stderr, "Unable to open wave file %s for writing\n", fileName);
return NULL;
}
file = (waveFile)calloc(1, sizeof(struct waveFileStruct));
file->soundFile = soundFile;
file->sampleRate = sampleRate;
file->numChannels = numChannels;
writeHeader(file, sampleRate, numChannels);
if (file->failed) {
closeFile(file);
return NULL;
}
return file;
}
/* Close the sound file. */
int closeWaveFile(waveFile file) {
FILE* soundFile = file->soundFile;
int passed = 1;
if (!file->isInput) {
if (fseek(soundFile, 4, SEEK_SET) != 0) {
fprintf(stderr, "Failed to seek on input file.\n");
passed = 0;
} else {
/* Now update the file to have the correct size. */
writeInt(file, file->bytesWritten - 8);
if (file->failed) {
fprintf(stderr, "Failed to write wave file size.\n");
passed = 0;
}
if (fseek(soundFile, 40, SEEK_SET) != 0) {
fprintf(stderr, "Failed to seek on input file.\n");
passed = 0;
} else {
/* Now update the file to have the correct size. */
writeInt(file, file->bytesWritten - 48);
if (file->failed) {
fprintf(stderr, "Failed to write wave file size.\n");
passed = 0;
}
}
}
}
closeFile(file);
return passed;
}
/* Read from the wave file. Return the number of samples read.
numSamples and maxSamples are the number of **multi-channel** samples */
int readFromWaveFile(waveFile file, short* buffer, int maxSamples) {
int i, bytesRead, samplesRead;
int bytePos = 0;
unsigned char bytes[WAVE_BUF_LEN];
short sample;
if (maxSamples * file->numChannels * 2 > WAVE_BUF_LEN) {
maxSamples = WAVE_BUF_LEN / (file->numChannels * 2);
}
bytesRead = readBytes(file, bytes, maxSamples * file->numChannels * 2);
samplesRead = bytesRead / (file->numChannels * 2);
for (i = 0; i < samplesRead * file->numChannels; i++) {
sample = bytes[bytePos++];
sample |= (unsigned int)bytes[bytePos++] << 8;
*buffer++ = sample;
}
return samplesRead;
}
/* Write to the wave file. */
int writeToWaveFile(waveFile file, short* buffer, int numSamples) {
int i;
int bytePos = 0;
unsigned char bytes[WAVE_BUF_LEN];
short sample;
int total = numSamples * file->numChannels;
for (i = 0; i < total; i++) {
if (bytePos == WAVE_BUF_LEN) {
writeBytes(file, bytes, bytePos);
bytePos = 0;
}
sample = buffer[i];
bytes[bytePos++] = sample;
bytes[bytePos++] = sample >> 8;
}
if (bytePos != 0) {
writeBytes(file, bytes, bytePos);
}
return file->failed;
}