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/******************************************************************************
*
* Copyright 2022 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************/
#include <stdint.h>
#include "wave.h"
/**
* Id formatting
*/
#define __WAVE_ID(s) \
(uint32_t)( s[0] | (s[1] << 8) | (s[2] << 16) | (s[3] << 24) )
/**
* File format statement
* | type_id WAVE_FILE_TYPE_ID
* | size File size - 8 bytes
* | type_id WAVE_FILE_FMT_ID
*/
#define WAVE_FILE_TYPE_ID __WAVE_ID("RIFF")
#define WAVE_FILE_FMT_ID __WAVE_ID("WAVE")
struct wave_file {
uint32_t type_id;
uint32_t size;
uint32_t fmt_id;
};
/**
* Audio format statement
* | id WAVE_FORMAT_ID
* | size Size of the block - 8 bytes (= 16 bytes)
* | format WAVE_FORMAT_PCM
* | channels Number of channels
* | samplerate Sampling rate
* | byterate Bytes per secondes = `samplerate * framesize`
* | framesize Bytes per sampling time = `channels * bitdepth / 8`
* | bitdepth Number of bits per sample
*/
#define WAVE_FORMAT_ID __WAVE_ID("fmt ")
#define WAVE_FORMAT_PCM 1
struct wave_format {
uint32_t id;
uint32_t size;
uint16_t fmt;
uint16_t channels;
uint32_t samplerate;
uint32_t byterate;
uint16_t framesize;
uint16_t bitdepth;
};
/**
* Audio data statement
* | id WAV_DATA_ID
* | size Size of the data following
*/
#define WAVE_DATA_ID __WAVE_ID("data")
struct wave_data {
uint32_t id;
uint32_t size;
};
/**
* Read WAVE file header
*/
int wave_read_header(FILE *fp, int *bitdepth, int *samplesize,
int *samplerate, int *nchannels, int *nframes)
{
struct wave_file file;
struct wave_format format;
struct wave_data data;
if (fread(&file, sizeof(file), 1, fp) != 1
|| file.type_id != WAVE_FILE_TYPE_ID
|| file.fmt_id != WAVE_FILE_FMT_ID)
return -1;
if (fread(&format, sizeof(format), 1, fp) != 1
|| format.id != WAVE_FORMAT_ID
|| format.fmt != WAVE_FORMAT_PCM
|| format.byterate != format.samplerate * format.framesize)
return -1;
fseek(fp, sizeof(format) - (8 + format.size), SEEK_CUR);
if (fread(&data, sizeof(data), 1, fp) != 1
|| data.id != WAVE_DATA_ID)
return -1;
*bitdepth = format.bitdepth;
*samplesize = format.framesize / format.channels;
*samplerate = format.samplerate;
*nchannels = format.channels;
*nframes = data.size / format.framesize;
return 0;
}
/**
* Read PCM samples from wave file
*/
int wave_read_pcm(FILE *fp, int samplesize,
int nch, int count, void *buffer)
{
return fread(buffer, nch * samplesize, count, fp);
}
/**
* Write WAVE file header
*/
void wave_write_header(FILE *fp, int bitdepth, int samplesize,
int samplerate, int nchannels, int nframes)
{
struct {
struct wave_file file;
struct wave_format format;
struct wave_data data;
} header;
long data_size = nchannels * nframes * samplesize;
long file_size = sizeof(header) + data_size;
header.file = (struct wave_file){
WAVE_FILE_TYPE_ID, file_size - 8,
.fmt_id = WAVE_FILE_FMT_ID
};
header.format = (struct wave_format){
WAVE_FORMAT_ID, sizeof(header.format) - 8,
.fmt = WAVE_FORMAT_PCM,
.channels = nchannels,
.samplerate = samplerate,
.byterate = samplerate * nchannels * samplesize,
.framesize = nchannels * samplesize,
.bitdepth = bitdepth,
};
header.data = (struct wave_data){
WAVE_DATA_ID, data_size
};
fwrite(&header, sizeof(header), 1, fp);
}
/**
* Write PCM samples to wave file
*/
void wave_write_pcm(FILE *fp, int samplesize,
const void *_pcm, int nch, int off, int count)
{
const int8_t *pcm = _pcm;
fwrite(pcm + nch * off * samplesize, nch * samplesize, count, fp);
}
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