Stream-PDM/converter.c
Oliver Schmidt b8365565f3 Added PDM converter.
The program requires a mono 78670Hz 32-bit-float headerless PCM file.
2020-05-10 00:11:03 +02:00

91 lines
2.0 KiB
C

#define _CRT_NONSTDC_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS
#include <io.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <sys/stat.h>
#define BITS 8
void main(int argc, const char *argv[])
{
if (argc != 2)
{
fprintf(stderr, "usage: %s file\n", argv[0]);
return;
}
char name[256];
sprintf(name, "%s.raw", argv[1]);
int source = open(name, O_RDONLY | O_BINARY);
fprintf(stderr, "source: %s\n", name);
if (source == -1)
{
perror("source");
return;
}
sprintf(name, "%s.a2stream", argv[1]);
int target = open(name, O_WRONLY | O_BINARY | O_CREAT | O_TRUNC, S_IREAD | S_IWRITE);
fprintf(stderr, "target: %s\n", name);
if (target == -1)
{
close(source);
perror("target");
return;
}
int samples = 0;
int size;
float error = 0.0;
bool last = false;
do
{
float x[256 * BITS];
size = read(source, x, sizeof(x)) / sizeof(float);
if (size == -1)
{
perror("source");
close(source);
close(target);
return;
}
unsigned char y[256];
memset(y, 0, sizeof(y));
// first-order delta-sigma converter
for (int n = 0; n < size; n++)
{
bool next = x[n] >= error;
error = (next ? 1.0 : -1.0) - x[n] + error;
if (next != last)
{
y[n / BITS] |= 1 << (n % BITS);
}
last = next;
}
if (write(target, y, size / BITS) != size / BITS)
{
perror("target");
close(source);
close(target);
return;
}
samples += size;
int h = (samples / 78670 / 3600);
int m = (samples / 78670 / 60) % 60;
int s = (samples / 78670 ) % 60;
fprintf(stderr, "offset: %02d:%02d:%02d\r", h, m, s);
}
while (size);
close(source);
close(target);
}