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martin modes, and some bugfixes to get them working

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rattatwinko
2026-02-22 19:38:10 +01:00
parent 16c5bbf28a
commit ba38a51a68
6 changed files with 162 additions and 22 deletions
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40
sstv.c
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@@ -5,16 +5,19 @@
#include <math.h>
#include <stdint.h>
#define PI 3.14159265358979
#define PI 3.14159265358979
#define AMPLITUDE 12000
static double phase = 0.0;
static double phase = 0.0;
static double sample_accum = 0.0; // accumulator
void sstv_tone(wav_t *wav, double freq, double duration_ms) {
uint32_t total_samples = (uint32_t)((duration_ms / 1000.0) * wav->sample_rate);
sample_accum += (duration_ms / 1000.0) * wav->sample_rate;
uint32_t total_samples = (uint32_t)sample_accum;
sample_accum -= total_samples;
double step = 2.0 * PI * freq / wav->sample_rate;
for (uint32_t i = 0; i < total_samples; i++) {
double step = 2.0 * PI * freq / wav->sample_rate;
phase += step;
if (phase > 2.0 * PI)
phase -= 2.0 * PI;
@@ -24,31 +27,36 @@ void sstv_tone(wav_t *wav, double freq, double duration_ms) {
}
}
void sstv_vis_header(wav_t *wav) {
uint8_t vis = 0x08;
uint8_t parity = 0;
void sstv_vis_header_ex(wav_t *wav, uint8_t vis_code) {
// reset accumulator
phase = 0.0;
sample_accum = 0.0;
/* preamble */
sstv_tone(wav, 1900, 300);
sstv_tone(wav, 1200, 10);
sstv_tone(wav, 1200, 10);
sstv_tone(wav, 1900, 300);
sstv_tone(wav, 1200, 30);
uint8_t parity = 0;
for (int i = 0; i < 7; i++) {
uint8_t bit = (vis >> i) & 1;
if (bit) {
sstv_tone(wav, 1100, 30);
parity ^= 1;
} else {
sstv_tone(wav, 1300, 30);
}
uint8_t bit = (vis_code >> i) & 1;
sstv_tone(wav, bit ? 1100 : 1300, 30);
parity ^= bit;
}
/* parity bit */
sstv_tone(wav, parity ? 1100 : 1300, 30);
/* stop bit */
sstv_tone(wav, 1200, 30);
}
void sstv_vis_header(wav_t *wav) {
sstv_vis_header_ex(wav, 0x08);
}
int sstv_encode_robot36(const char *input_image, const char *output_wav) {
image_t img, resized;
wav_t wav;