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#define PROGRAM_NAME "pcm"
#define USAGE_OPTS "infile.wav outfile.pcm"
#include "common.h"
#define CHUNKID(b1, b2, b3, b4) (uint32_t)((uint32_t)(b1) | ((uint32_t)(b2) << 8) | ((uint32_t)(b3) << 16) | ((uint32_t)(b4) << 24))
int32_t get_uint16le(uint8_t *data, long size, long i) {
return i + 2 < size ? (int32_t)data[i] | ((int32_t)data[i + 1] << 8) : -1;
}
int64_t get_uint32le(uint8_t *data, long size, long i) {
return i + 4 < size ? (int64_t)data[i] | ((int64_t)data[i + 1] << 8) | ((int64_t)data[i + 2] << 16) | ((int64_t)data[i + 3] << 24) : -1;
}
uint8_t *wav2pcm(uint8_t *wavdata, long wavsize, size_t *pcmsize) {
int64_t fourcc = get_uint32le(wavdata, wavsize, 0);
if (fourcc != CHUNKID('R', 'I', 'F', 'F')) {
error_exit("WAV file does not start with 'RIFF'\n");
}
int64_t waveid = get_uint32le(wavdata, wavsize, 8);
if (waveid != CHUNKID('W', 'A', 'V', 'E')) {
error_exit("RIFF chunk does not start with 'WAVE'\n");
}
long sample_offset = 0;
int64_t num_samples = 0;
int64_t riffsize = get_uint32le(wavdata, wavsize, 4) + 8;
for (long i = 12; i < riffsize;) {
int64_t chunkid = get_uint32le(wavdata, wavsize, i);
int64_t chunksize = get_uint32le(wavdata, wavsize, i + 4);
if (chunksize == -1) {
error_exit("Failed to read sub-chunk size\n");
}
i += 8;
// Require 22050 Hz 8-bit PCM WAV audio
if (chunkid == CHUNKID('f', 'm', 't', ' ')) {
int32_t audio_format = get_uint16le(wavdata, wavsize, i);
if (audio_format != 1) {
error_exit("WAV data is not PCM format\n");
}
int32_t num_channels = get_uint16le(wavdata, wavsize, i + 2);
if (num_channels != 1) {
error_exit("WAV data is not mono\n");
}
int64_t sample_rate = get_uint32le(wavdata, wavsize, i + 4);
if (sample_rate != 22050) {
error_exit("WAV data is not 22050 Hz\n");
}
int32_t bits_per_sample = get_uint16le(wavdata, wavsize, i + 14);
if (bits_per_sample != 8) {
error_exit("WAV data is not 8-bit\n");
}
}
else if (chunkid == CHUNKID('d', 'a', 't', 'a')) {
sample_offset = i;
num_samples = chunksize;
break;
}
i += chunksize;
}
if (!num_samples) {
error_exit("WAV data has no PCM samples\n");
}
// Pack 8 WAV samples per PCM byte, clamping each to 0 or 1
*pcmsize = (size_t)((num_samples + 7) / 8);
uint8_t *pcmdata = xmalloc(*pcmsize);
for (int64_t i = 0; i < num_samples; i += 8) {
uint8_t v = 0;
for (int64_t j = 0; j < 8 && i + j < num_samples; j++) {
v |= (wavdata[sample_offset + i + j] > 0x80) << (7 - j);
}
pcmdata[i / 8] = v;
}
return pcmdata;
}
int main(int argc, char *argv[]) {
if (argc != 3) {
usage_exit(1);
}
long wavsize;
uint8_t *wavdata = read_u8(argv[1], &wavsize);
size_t pcmsize;
uint8_t *pcmdata = wav2pcm(wavdata, wavsize, &pcmsize);
write_u8(argv[2], pcmdata, pcmsize);
free(wavdata);
free(pcmdata);
return 0;
}
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