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#include "wav.h"
#include "smrt_arena.h"
#include <assert.h>
#include <stdio.h>
#include <string.h>
b32 seek_to_chunk(FILE *file, char const *chunk_name) {
char cur_name[4];
u32 chunk_size;
fseek(file, 0, SEEK_END);
const i64 max_pos = ftell(file);
fseek(file, sizeof(wav_master_chunk_t), SEEK_SET);
while (true) {
fread(cur_name, 4, 1, file);
fread(&chunk_size, 4, 1, file);
if (memcmp(cur_name, chunk_name, 4) == 0) break;
if (chunk_size % 2 == 1) chunk_size++;
if (ftell(file) + (i64)chunk_size >= max_pos) return false;
fseek(file, chunk_size, SEEK_CUR);
}
fseek(file, -8, SEEK_CUR);
return true;
}
wav_data_t load_wav_file(smrt_arena_t *arena, char *filename, wav_master_chunk_t *master_o, wav_fmt_chunk_t *format_o) {
wav_data_t data = { 0 };
FILE *wav_file = fopen(filename, "rb");
if (!wav_file) return data;
fread(master_o, sizeof(wav_master_chunk_t), 1, wav_file);
if (seek_to_chunk(wav_file, "fmt ") == false) return data;
fread(format_o, sizeof(wav_fmt_chunk_t), 1, wav_file);
if (seek_to_chunk(wav_file, "data") == false) return data;
fseek(wav_file, 4, SEEK_CUR);
u32 sampled_data_size;
fread(&sampled_data_size, 4, 1, wav_file);
data.samples = smrt_arena_push(arena, sizeof(wav_data_t) + sampled_data_size, true);
if (!data.samples) return data;
fread((u8*)data.samples+WAV_DATA_BASE_POS, sampled_data_size, 1, wav_file);
data.sample_count = sampled_data_size / ((format_o->bits_per_sample / 8) * format_o->num_channels);
return data;
}
b32 write_wav_file(char *filename, wav_fmt_chunk_t *fmt_chunk_i, wav_data_t data_i) {
FILE *wav_file = fopen(filename, "wb");
if (!wav_file) return false;
u64 data_size_bytes = data_i.sample_count * fmt_chunk_i->bytes_per_block;
wav_master_chunk_t mchunk = {
.file_size = sizeof(wav_master_chunk_t) + sizeof(wav_fmt_chunk_t) + sizeof(wav_data_t) + data_size_bytes
};
memcpy(&mchunk.chunk_id, "RIFF", 4);
memcpy(&mchunk.file_format_id, "WAVE", 4);
fwrite(&mchunk, sizeof(wav_master_chunk_t), 1, wav_file);
fwrite(fmt_chunk_i, sizeof(wav_data_t), 1, wav_file);
fwrite(data_i.samples, sizeof(u8), data_size_bytes, wav_file);
return true;
}
wav_fmt_chunk_t make_wav_fmt_chunk(u32 num_channels, u32 sample_rate, u16 bits_per_sample, wav_data_t data_i) {
u64 data_size_bytes = data_i.sample_count * (num_channels * (bits_per_sample / 8));
wav_fmt_chunk_t o = {
.chunk_size = sizeof(wav_fmt_chunk_t) + data_size_bytes - 8,
.bits_per_sample = bits_per_sample,
.num_channels = num_channels,
.sample_rate = sample_rate,
.bytes_per_block = num_channels * (bits_per_sample / 8),
.audio_format = 1,
};
o.bytes_per_sec = o.bytes_per_block * sample_rate;
memcpy(&o.chunk_id, "data", 4);
return o;
}
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