On 27-11-07 02:26, Rene Herman wrote:
Wrote a small sine generator during this test by the way -- attached
just in case anyone is interested. Writes S16_LE to stdout, so intended
to be used as:
$ sine -f <freq> -d <dbspl> | aplay -f cd
-r <rate> for setting a different rate than 44100:
$ sine -f <freq> -d <dbspl> -r <rate> | aplay -f S16_LE -c 2 -r <rate>
Sigh, did it again...
s/#ifdef __LITTLE_ENDIAN/#if __BYTE_ORDER == __LITTLE_ENDIAN/
By the way, I should also really comment that NOONE SHOULD listen TO
ANYTHING, INCLUDING SINE WAVES, AT HIGH LEVELS.
Most setups will be perfectly capable of damaging on's hearing, so always be
careful. This program generates 0 dBFS (LOUDEST!) samples by default, so if
anyone tries something, turn things down first!
And yes, I'd generally assume that people aren't idiots, but it's probably
good to warn anyway given that this is being posted in the context of
hearing tests and all...
Rene
/*
* Generates a stereo S16_LE sine at settable rate, frequency and dBFS
*
* gcc -W -Wall -o sine sine.c -lm
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <math.h>
#include <unistd.h>
#define RATE_MIN 8000
#define RATE_MAX 192000
#define FREQ_MIN 20
#define FREQ_MAX 30000
#define DBFS_MIN -((16 * 20 * M_LN2) / M_LN10)
#define DBFS_MAX 0
#define RATE 44100
#define FREQ 440
#define DBFS 0
static inline uint16_t le(uint16_t val)
{
#if __BYTE_ORDER == __LITTLE_ENDIAN
return val;
#else
return bswap_16(val);
#endif
}
int main(int argc, char *argv[])
{
int rate = RATE;
int freq = FREQ;
double dbfs = DBFS;
double ampl;
int i;
while ((i = getopt(argc, argv, "r:f:d:")) != -1) {
char *endptr;
switch (i) {
case 'r':
rate = strtol(optarg, &endptr, 0);
if (rate < RATE_MIN || rate > RATE_MAX || *endptr)
goto usage;
break;
case 'f':
freq = strtol(optarg, &endptr, 0);
if (freq < FREQ_MIN || freq > FREQ_MAX || *endptr)
goto usage;
break;
case 'd':
dbfs = strtod(optarg, &endptr);
if (dbfs < DBFS_MIN || dbfs > DBFS_MAX || *endptr)
goto usage;
break;
default:
return EXIT_FAILURE;
}
}
if (rate < 2 * freq) {
usage:
printf("usage: %s [-r <rate>] [-f <freq>] [-d <dbfs>]\n",
argv[0]);
return EXIT_FAILURE;
}
ampl = 32767.0 / pow(10, -dbfs / 20);
while (1)
for (i = 0; i < rate; i++) {
uint16_t sample = le(ampl * sin(((2 * i * freq) * M_PI)
/ rate));
write(STDOUT_FILENO, &sample, sizeof sample);
write(STDOUT_FILENO, &sample, sizeof sample);
}
return EXIT_SUCCESS;
}
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