diff --git a/Makefile b/Makefile
index a90dfe9..3e99959 100644
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,7 @@ clean:
encode: encode.o mmap_file.o pcm.o wav.o alsa.o yuv.o img.o ppm.o sdl.o
-decode: decode.o mmap_file.o pcm.o wav.o alsa.o window.o ddc.o delay.o yuv.o img.o ppm.o sdl.o
+decode: decode.o mmap_file.o pcm.o wav.o alsa.o window.o ddc.o buffer.o yuv.o img.o ppm.o sdl.o
-debug: debug.o mmap_file.o pcm.o wav.o alsa.o window.o ddc.o delay.o yuv.o img.o ppm.o sdl.o
+debug: debug.o mmap_file.o pcm.o wav.o alsa.o window.o ddc.o buffer.o yuv.o img.o ppm.o sdl.o
diff --git a/delay.c b/buffer.c
similarity index 54%
rename from delay.c
rename to buffer.c
index e5e7cc6..e860467 100644
--- a/delay.c
+++ b/buffer.c
@@ -5,31 +5,34 @@ To the extent possible under law, the author(s) have dedicated all copyright and
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see .
*/
-
-#include "delay.h"
+#include "buffer.h"
#include
-float do_delay(struct delay *d, float input)
+float *do_buffer(struct buffer *d, float input)
{
- d->s[d->last] = input;
- d->last = (d->last + 1) < d->len ? d->last + 1 : 0;
- return d->s[d->last];
+ d->s[d->last0] = input;
+ d->s[d->last1] = input;
+ d->last0 = (d->last0 - 1) < 0 ? d->len : d->last0 - 1;
+ d->last1 = (d->last1 - 1) < 0 ? d->len : d->last1 - 1;
+ int last = d->last0 < d->last1 ? d->last0 : d->last1;
+ return d->s + last;
}
-struct delay *alloc_delay(int samples)
+struct buffer *alloc_buffer(int samples)
{
- int len = samples + 1;
- struct delay *d = malloc(sizeof(struct delay));
+ int len = 2 * samples;
+ struct buffer *d = malloc(sizeof(struct buffer));
d->s = malloc(sizeof(float) * len);
- d->last = 0;
+ d->last0 = 0;
+ d->last1 = samples;
d->len = len;
for (int i = 0; i < len; i++)
d->s[i] = 0.0;
return d;
}
-void free_delay(struct delay *delay)
+void free_buffer(struct buffer *buffer)
{
- free(delay->s);
- free(delay);
+ free(buffer->s);
+ free(buffer);
}
diff --git a/delay.h b/buffer.h
similarity index 72%
rename from delay.h
rename to buffer.h
index 64ea1dd..77d5477 100644
--- a/delay.h
+++ b/buffer.h
@@ -5,17 +5,17 @@ To the extent possible under law, the author(s) have dedicated all copyright and
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see .
*/
-
-#ifndef DELAY_H
-#define DELAY_H
-struct delay {
+#ifndef BUFFER_H
+#define BUFFER_H
+struct buffer {
float *s;
- int last;
+ int last0;
+ int last1;
int len;
};
-float do_delay(struct delay *, float);
-struct delay *alloc_delay(int);
-void free_delay(struct delay *);
+float *do_buffer(struct buffer *d, float input);
+struct buffer *alloc_buffer(int samples);
+void free_buffer(struct buffer *buffer);
#endif
diff --git a/ddc.c b/ddc.c
index b895065..848da21 100644
--- a/ddc.c
+++ b/ddc.c
@@ -5,78 +5,70 @@ To the extent possible under law, the author(s) have dedicated all copyright and
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see .
*/
-
+#include
#include
#include
-#include
#include "window.h"
#include "ddc.h"
-void do_ddc(struct ddc *ddc, float *input, float complex *output)
+void do_ddc(struct ddc *ddc, float *input, complex float *output)
{
- // this works only for L <= M
- for (int k = 0, last = ddc->last, in = 0; k < ddc->L; k++) {
- while (ddc->skip < ddc->M) {
- ddc->s[ddc->last] = input[in++];
- last = ddc->last;
- ddc->last = (ddc->last + 1) < ddc->samples ? ddc->last + 1 : 0;
- ddc->skip += ddc->L;
- }
+ int N = ddc->N;
+ int M = ddc->M;
+ int L = ddc->L;
+ int offset = 0;
+ for (int k = 0; k < L; k++) {
+ float *x = input + (((L * M - 1) - offset) / L);
+ complex float *b = ddc->b + (N * (offset % L));
+ offset += M;
- ddc->skip %= ddc->M;
-
- float complex sum = 0.0;
- for (int i = ddc->offset; i < ddc->taps; i += ddc->L) {
- sum += ddc->b[i] * ddc->s[last];
- last += last ? - 1 : ddc->samples - 1;
- }
-
- ddc->offset = (ddc->offset + ddc->M) % ddc->L;
+ complex float sum = 0.0;
+ for (int i = 0; i < N; i++)
+ sum += b[i] * x[i];
output[k] = ddc->osc * sum;
ddc->osc *= ddc->d;
-// ddc->osc /= cabsf(ddc->osc); // not really needed
+ // ddc->osc /= cabsf(ddc->osc); // not really needed
}
}
-struct ddc *alloc_ddc(float freq, float bw, float step, int taps, int L, int M, float (*window)(float, float, float), float a)
+struct ddc *alloc_ddc(int L, int M, float carrier, float bw, float rate, int taps, float (*window)(float, float, float), float a)
{
- float lstep = step / (float)L;
- float ostep = step * (float)M / (float)L;
+ float lstep = 1.0 / ((float)L * rate);
+ float ostep = (float)M * lstep;
struct ddc *ddc = malloc(sizeof(struct ddc));
- ddc->taps = taps;
- ddc->samples = (taps + L - 1) / L;
- ddc->b = malloc(sizeof(float complex) * ddc->taps);
- ddc->s = malloc(sizeof(float) * ddc->samples);
+ ddc->N = (taps + L - 1) / L;
+ ddc->b = malloc(sizeof(complex float) * ddc->N * L);
ddc->osc = I;
- ddc->d = cexpf(-I * 2.0 * M_PI * freq * ostep);
- ddc->offset = (M - 1) % L;
- ddc->last = 0;
- ddc->skip = 0;
+ ddc->d = cexpf(-I * 2.0 * M_PI * carrier * ostep);
ddc->L = L;
ddc->M = M;
- for (int i = 0; i < ddc->samples; i++)
- ddc->s[i] = 0.0;
+ complex float *b = malloc(sizeof(complex float) * taps);
float sum = 0.0;
- for (int i = 0; i < ddc->taps; i++) {
- float N = (float)ddc->taps;
- float n = (float)i;
+ for (int i = 0; i < taps; i++) {
+ float N = taps;
+ float n = i;
float x = n - (N - 1.0) / 2.0;
- float l = 2.0 * M_PI * bw * lstep;
- float w = window(n, ddc->taps, a);
- float h = 0.0 == x ? l / M_PI : sinf(l * x) / (x * M_PI);
- float b = w * h;
- sum += b;
- complex float o = cexpf(I * 2.0 * M_PI * freq * lstep * n);
- ddc->b[i] = b * o * (float)L;
+ float l = 2.0 * bw * lstep;
+ float h = l * sinc(l * x);
+ float w = window(n, N, a);
+ float t = w * h;
+ sum += t;
+ complex float o = cexpf(I * 2.0 * M_PI * carrier * lstep * n);
+ b[i] = t * o;
}
- for (int i = 0; i < ddc->taps; i++)
- ddc->b[i] /= sum;
+ for (int i = 0; i < taps; i++)
+ b[i] /= sum;
+ for (int i = 0; i < ddc->N * L; i++)
+ ddc->b[i] = 0.0;
+ for (int i = 0; i < L; i++)
+ for (int j = i, k = 0; j < taps; j += L, k++)
+ ddc->b[i * ddc->N + k] = b[j];
+ free(b);
return ddc;
}
void free_ddc(struct ddc *ddc)
{
free(ddc->b);
- free(ddc->s);
free(ddc);
}
diff --git a/ddc.h b/ddc.h
index e539f60..c3e187d 100644
--- a/ddc.h
+++ b/ddc.h
@@ -5,28 +5,22 @@ To the extent possible under law, the author(s) have dedicated all copyright and
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see .
*/
-
#ifndef DDC_H
#define DDC_H
#include "window.h"
struct ddc {
- float complex *b;
- float *s;
- float complex osc;
- float complex d;
- int offset;
- int skip;
- int last;
- int taps;
- int samples;
+ complex float *b;
+ complex float osc;
+ complex float d;
+ int N;
int L;
int M;
};
-void do_ddc(struct ddc *, float *, float complex *);
-struct ddc *alloc_ddc(float, float, float, int, int, int, float (*)(float, float, float), float);
-void free_ddc(struct ddc *);
+void do_ddc(struct ddc *ddc, float *input, complex float *output);
+struct ddc *alloc_ddc(int L, int M, float carrier, float bw, float rate, int taps, float (*window)(float, float, float), float a);
+void free_ddc(struct ddc *ddc);
#endif
diff --git a/debug.c b/debug.c
index 37beb5d..4c3fb2b 100644
--- a/debug.c
+++ b/debug.c
@@ -15,7 +15,7 @@ You should have received a copy of the CC0 Public Domain Dedication along with t
#include "mmap_file.h"
#include "pcm.h"
#include "ddc.h"
-#include "delay.h"
+#include "buffer.h"
#include "yuv.h"
#include "utils.h"
#include "img.h"
@@ -47,7 +47,6 @@ int main(int argc, char **argv)
if (channels > 1)
fprintf(stderr, "using first of %d channels\n", channels);
- const float step = 1.0 / rate;
float complex cnt_last = -I;
float complex dat_last = -I;
@@ -105,18 +104,19 @@ int main(int argc, char **argv)
float drate = rate * (float)factor_L / (float)factor_M;
float dstep = 1.0 / drate;
fprintf(stderr, "using factor of %ld/%ld, working at %.2fhz\n", factor_L, factor_M, drate);
- float *cnt_amp = malloc(sizeof(float) * factor_M);
- float *dat_amp = malloc(sizeof(float) * factor_M);
float complex *cnt_q = malloc(sizeof(float complex) * factor_L);
float complex *dat_q = malloc(sizeof(float complex) * factor_L);
// same factor to keep life simple and have accurate horizontal sync
- struct ddc *cnt_ddc = alloc_ddc(1200.0, 200.0, step, cnt_taps, factor_L, factor_M, kaiser, 2.0);
- struct ddc *dat_ddc = alloc_ddc(1900.0, 800.0, step, dat_taps, factor_L, factor_M, kaiser, 2.0);
+ struct ddc *cnt_ddc = alloc_ddc(factor_L, factor_M, 1200.0, 200.0, rate, cnt_taps, kaiser, 2.0);
+ struct ddc *dat_ddc = alloc_ddc(factor_L, factor_M, 1900.0, 800.0, rate, dat_taps, kaiser, 2.0);
// delay input by phase shift of other filter to synchronize outputs
- struct delay *cnt_delay = alloc_delay((dat_taps - 1) / (2 * factor_L));
- struct delay *dat_delay = alloc_delay((cnt_taps - 1) / (2 * factor_L));
+ int cnt_delay = (dat_taps - 1) / (2 * factor_L);
+ int dat_delay = (cnt_taps - 1) / (2 * factor_L);
- short *buff = (short *)malloc(sizeof(short) * channels * factor_M);
+ short *pcm_buff = (short *)malloc(sizeof(short) * channels * factor_M);
+
+ // 0.1 second history + enough room for delay and taps
+ struct buffer *buffer = alloc_buffer(0.1 * rate + 2 * fmaxf(cnt_delay, dat_delay));
const float sync_porch_len = 0.003;
const float porch_len = 0.0015; (void)porch_len;
@@ -143,15 +143,14 @@ int main(int argc, char **argv)
for (int out = factor_L;; out++, hor_ticks++, cal_ticks++, vis_ticks++) {
if (out >= factor_L) {
out = 0;
- if (!read_pcm(pcm, buff, factor_M))
+ if (!read_pcm(pcm, pcm_buff, factor_M))
break;
- for (int j = 0; j < factor_M; j++) {
- float amp = (float)buff[j * channels] / 32767.0;
- cnt_amp[j] = do_delay(cnt_delay, amp);
- dat_amp[j] = do_delay(dat_delay, amp);
- }
- do_ddc(cnt_ddc, cnt_amp, cnt_q);
- do_ddc(dat_ddc, dat_amp, dat_q);
+ float *buff = 0;
+ for (int j = 0; j < factor_M; j++)
+ buff = do_buffer(buffer, (float)pcm_buff[j * channels] / 32767.0);
+
+ do_ddc(cnt_ddc, buff + cnt_delay, cnt_q);
+ do_ddc(dat_ddc, buff + dat_delay, dat_q);
}
float cnt_freq = fclampf(1200.0 + cargf(cnt_q[out] * conjf(cnt_last)) / (2.0 * M_PI * dstep), 1100.0, 1300.0);
@@ -417,8 +416,8 @@ int main(int argc, char **argv)
free_ddc(cnt_ddc);
free_ddc(dat_ddc);
- free(cnt_amp);
- free(dat_amp);
+ free_buffer(buffer);
+ free(pcm_buff);
return 0;
}
diff --git a/decode.c b/decode.c
index 62b8798..33c6848 100644
--- a/decode.c
+++ b/decode.c
@@ -14,7 +14,7 @@ You should have received a copy of the CC0 Public Domain Dedication along with t
#include
#include "pcm.h"
#include "ddc.h"
-#include "delay.h"
+#include "buffer.h"
#include "yuv.h"
#include "utils.h"
#include "img.h"
@@ -289,23 +289,20 @@ int demodulate(struct pcm *pcm, float *cnt_freq, float *dat_freq, float *drate)
static float dstep;
static float complex cnt_last = -I;
static float complex dat_last = -I;
- static float *cnt_amp;
- static float *dat_amp;
static float complex *cnt_q;
static float complex *dat_q;
static struct ddc *cnt_ddc;
static struct ddc *dat_ddc;
- static struct delay *cnt_delay;
- static struct delay *dat_delay;
- static short *buff;
+ static struct buffer *buffer;
+ static int cnt_delay;
+ static int dat_delay;
+ static short *pcm_buff;
static int init = 0;
if (!init) {
init = 1;
rate = rate_pcm(pcm);
channels = channels_pcm(pcm);
- const float step = 1.0 / rate;
-
#if DN && UP
// 320 / 0.088 = 160 / 0.044 = 40000 / 11 = 3636.(36)~ pixels per second for Y, U and V
factor_L = 40000;
@@ -331,18 +328,19 @@ int demodulate(struct pcm *pcm, float *cnt_freq, float *dat_freq, float *drate)
*drate = rate * (float)factor_L / (float)factor_M;
dstep = 1.0 / *drate;
fprintf(stderr, "using factor of %ld/%ld, working at %.2fhz\n", factor_L, factor_M, *drate);
- cnt_amp = malloc(sizeof(float) * factor_M);
- dat_amp = malloc(sizeof(float) * factor_M);
cnt_q = malloc(sizeof(float complex) * factor_L);
dat_q = malloc(sizeof(float complex) * factor_L);
// same factor to keep life simple and have accurate horizontal sync
- cnt_ddc = alloc_ddc(1200.0, 200.0, step, cnt_taps, factor_L, factor_M, kaiser, 2.0);
- dat_ddc = alloc_ddc(1900.0, 800.0, step, dat_taps, factor_L, factor_M, kaiser, 2.0);
+ cnt_ddc = alloc_ddc(factor_L, factor_M, 1200.0, 200.0, rate, cnt_taps, kaiser, 2.0);
+ dat_ddc = alloc_ddc(factor_L, factor_M, 1900.0, 800.0, rate, dat_taps, kaiser, 2.0);
// delay input by phase shift of other filter to synchronize outputs
- cnt_delay = alloc_delay((dat_taps - 1) / (2 * factor_L));
- dat_delay = alloc_delay((cnt_taps - 1) / (2 * factor_L));
+ cnt_delay = (dat_taps - 1) / (2 * factor_L);
+ dat_delay = (cnt_taps - 1) / (2 * factor_L);
- buff = (short *)malloc(sizeof(short) * channels * factor_M);
+ pcm_buff = (short *)malloc(sizeof(short) * channels * factor_M);
+
+ // 0.1 second history + enough room for delay and taps
+ buffer = alloc_buffer(0.1 * rate + 2 * fmaxf(cnt_delay, dat_delay));
// start immediately below
out = factor_L;
@@ -350,22 +348,20 @@ int demodulate(struct pcm *pcm, float *cnt_freq, float *dat_freq, float *drate)
if (out >= factor_L) {
out = 0;
- if (!read_pcm(pcm, buff, factor_M)) {
+ if (!read_pcm(pcm, pcm_buff, factor_M)) {
init = 0;
- free(buff);
+ free(pcm_buff);
free_ddc(cnt_ddc);
free_ddc(dat_ddc);
- free(cnt_amp);
- free(dat_amp);
+ free_buffer(buffer);
return 0;
}
- for (int j = 0; j < factor_M; j++) {
- float amp = (float)buff[j * channels] / 32767.0;
- cnt_amp[j] = do_delay(cnt_delay, amp);
- dat_amp[j] = do_delay(dat_delay, amp);
- }
- do_ddc(cnt_ddc, cnt_amp, cnt_q);
- do_ddc(dat_ddc, dat_amp, dat_q);
+ float *buff = 0;
+ for (int j = 0; j < factor_M; j++)
+ buff = do_buffer(buffer, (float)pcm_buff[j * channels] / 32767.0);
+
+ do_ddc(cnt_ddc, buff + cnt_delay, cnt_q);
+ do_ddc(dat_ddc, buff + dat_delay, dat_q);
}
*cnt_freq = fclampf(1200.0 + cargf(cnt_q[out] * conjf(cnt_last)) / (2.0 * M_PI * dstep), 1100.0, 1300.0);