robot36/encode.c

/*
robot36 - encode and decode images using SSTV in Robot 36 mode
Written in 2011 by <Ahmet Inan> <xdsopl@googlemail.com>
To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
*/

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <complex.h> 
#include <limits.h>
#include "mmap_file.h"
#include "yuv.h"
#include "utils.h"
#include "pcm.h"

pcm_t *pcm;
complex float nco;
float hz2rad;
int channels;
short *buff;

int add_sample(float val) {
	for (int i = 0; i < channels; i++)
		buff[i] = (float)SHRT_MAX * val;
	return write_pcm(pcm, buff, 1);
}
void add_freq(float freq) {
	add_sample(creal(nco));
	nco *= cexpf(freq * hz2rad * I);
}

int main(int argc, char **argv)
{
	if (argc != 4) {
		fprintf(stderr, "usage: %s <input.ppm> <output.wav> <rate>\n", argv[0]);
		return 1;
	}

	size_t ppm_size;
	void *ppm_p;
	if (!mmap_file_ro(&ppm_p, argv[1], &ppm_size)) {
		fprintf(stderr, "couldnt open ppm file\n");
		return 1;
	}
	const int width = 320;
	const int height = 240;
	const char *ppm_head = "P6 320 240 255\n";

	if (strncmp(ppm_head, ppm_p, strlen(ppm_head))) {
		fprintf(stderr, "unsupported image file\n");
		return 1;
	}

	uint8_t *pixel = (uint8_t *)ppm_p + strlen(ppm_head);

	if (!open_pcm_write(&pcm, argv[2], atoi(argv[3]), 1, 37.5)) {
		fprintf(stderr, "couldnt open output %s\n", argv[2]);
		return 1;
	}

	float rate = rate_pcm(pcm);
	channels = channels_pcm(pcm);

	buff = (short *)malloc(sizeof(short)*channels);

	info_pcm(pcm);

	if (fabsf(0.0015 * rate - (int)(0.0015 * rate)) > 0.0001)
		fprintf(stderr, "this rate will not give accurate (smooth) results.\ntry 40000Hz and resample to %0.fHz\n", rate);

	hz2rad = (2.0 * M_PI) / rate;
	nco = -I * 0.7;
	enum { N = 13 };
	float seq_freq[N] = { 1900.0, 1200.0, 1900.0, 1200.0, 1300.0, 1300.0, 1300.0, 1100.0, 1300.0, 1300.0, 1300.0, 1100.0, 1200.0 };
	float seq_time[N] = { 0.3, 0.01, 0.3, 0.03, 0.03, 0.03, 0.03, 0.03, 0.03, 0.03, 0.03, 0.03, 0.03 };


	for (int ticks = 0; ticks < (int)(0.3 * rate); ticks++)
		add_sample(0.0);

	for (int i = 0; i < N; i++)
		for (int ticks = 0; ticks < (int)(seq_time[i] * rate); ticks++)
			add_freq(seq_freq[i]);

	for (int y = 0; y < height; y++) {
		// EVEN LINES
		// SYNC
		for (int ticks = 0; ticks < (int)(0.009 * rate); ticks++) {
			add_freq(1200.0);
		}
		// PORCH
		for (int ticks = 0; ticks < (int)(0.003 * rate); ticks++) {
			add_freq(1500.0);
		}
		// Y
		for (int ticks = 0; ticks < (int)(0.088 * rate); ticks++) {
			float xf = fclampf((320.0 * (float)ticks) / (0.088 * rate), 0.0, 319.0);
			int x0 = xf;
			int x1 = fclampf(x0 + 1, 0.0, 319.0);
			int off0 = 3 * y * width + 3 * x0;
			int off1 = 3 * y * width + 3 * x1;
			uint8_t R0 = pixel[off0 + 0];
			uint8_t G0 = pixel[off0 + 1];
			uint8_t B0 = pixel[off0 + 2];
			uint8_t R1 = pixel[off1 + 0];
			uint8_t G1 = pixel[off1 + 1];
			uint8_t B1 = pixel[off1 + 2];
			uint8_t R = flerpf(R0, R1, xf - (float)x0);
			uint8_t G = flerpf(G0, G1, xf - (float)x0);
			uint8_t B = flerpf(B0, B1, xf - (float)x0);
			add_freq(1500.0 + 800.0 * Y_RGB(R, G, B) / 255.0);
		}
		// EVEN
		for (int ticks = 0; ticks < (int)(0.0045 * rate); ticks++) {
			add_freq(1500.0);
		}
		// PORCH
		for (int ticks = 0; ticks < (int)(0.0015 * rate); ticks++) {
			add_freq(1900.0);
		}
		// V
		for (int ticks = 0; ticks < (int)(0.044 * rate); ticks++) {
			float xf = fclampf((160.0 * (float)ticks) / (0.044 * rate), 0.0, 159.0);
			int x0 = xf;
			int x1 = fclampf(x0 + 1, 0.0, 159.0);
			int evn0 = 3 * y * width + 6 * x0;
			int evn1 = 3 * y * width + 6 * x1;
			int odd0 = 3 * (y + 1) * width + 6 * x0;
			int odd1 = 3 * (y + 1) * width + 6 * x1;
			uint8_t R0 = (pixel[evn0 + 0] + pixel[odd0 + 0] + pixel[evn0 + 3] + pixel[odd0 + 3]) / 4;
			uint8_t G0 = (pixel[evn0 + 1] + pixel[odd0 + 1] + pixel[evn0 + 4] + pixel[odd0 + 4]) / 4;
			uint8_t B0 = (pixel[evn0 + 2] + pixel[odd0 + 2] + pixel[evn0 + 5] + pixel[odd0 + 5]) / 4;
			uint8_t R1 = (pixel[evn1 + 0] + pixel[odd1 + 0] + pixel[evn1 + 3] + pixel[odd1 + 3]) / 4;
			uint8_t G1 = (pixel[evn1 + 1] + pixel[odd1 + 1] + pixel[evn1 + 4] + pixel[odd1 + 4]) / 4;
			uint8_t B1 = (pixel[evn1 + 2] + pixel[odd1 + 2] + pixel[evn1 + 5] + pixel[odd1 + 5]) / 4;
			uint8_t R = flerpf(R0, R1, xf - (float)x0);
			uint8_t G = flerpf(G0, G1, xf - (float)x0);
			uint8_t B = flerpf(B0, B1, xf - (float)x0);
			add_freq(1500.0 + 800.0 * V_RGB(R, G, B) / 255.0);
		}
		// ODD LINES
		y++;
		// SYNC
		for (int ticks = 0; ticks < (int)(0.009 * rate); ticks++) {
			add_freq(1200.0);
		}
		// PORCH
		for (int ticks = 0; ticks < (int)(0.003 * rate); ticks++) {
			add_freq(1500.0);
		}
		// Y
		for (int ticks = 0; ticks < (int)(0.088 * rate); ticks++) {
			float xf = fclampf((320.0 * (float)ticks) / (0.088 * rate), 0.0, 319.0);
			int x0 = xf;
			int x1 = fclampf(x0 + 1, 0.0, 319.0);
			int off0 = 3 * y * width + 3 * x0;
			int off1 = 3 * y * width + 3 * x1;
			uint8_t R0 = pixel[off0 + 0];
			uint8_t G0 = pixel[off0 + 1];
			uint8_t B0 = pixel[off0 + 2];
			uint8_t R1 = pixel[off1 + 0];
			uint8_t G1 = pixel[off1 + 1];
			uint8_t B1 = pixel[off1 + 2];
			uint8_t R = flerpf(R0, R1, xf - (float)x0);
			uint8_t G = flerpf(G0, G1, xf - (float)x0);
			uint8_t B = flerpf(B0, B1, xf - (float)x0);
			add_freq(1500.0 + 800.0 * Y_RGB(R, G, B) / 255.0);
		}
		// ODD
		for (int ticks = 0; ticks < (int)(0.0045 * rate); ticks++) {
			add_freq(2300.0);
		}
		// PORCH
		for (int ticks = 0; ticks < (int)(0.0015 * rate); ticks++) {
			add_freq(1900.0);
		}
		// U
		for (int ticks = 0; ticks < (int)(0.044 * rate); ticks++) {
			float xf = fclampf((160.0 * (float)ticks) / (0.044 * rate), 0.0, 159.0);
			int x0 = xf;
			int x1 = fclampf(x0 + 1, 0.0, 159.0);
			int evn0 = 3 * (y - 1) * width + 6 * x0;
			int evn1 = 3 * (y - 1) * width + 6 * x1;
			int odd0 = 3 * y * width + 6 * x0;
			int odd1 = 3 * y * width + 6 * x1;
			uint8_t R0 = (pixel[evn0 + 0] + pixel[odd0 + 0] + pixel[evn0 + 3] + pixel[odd0 + 3]) / 4;
			uint8_t G0 = (pixel[evn0 + 1] + pixel[odd0 + 1] + pixel[evn0 + 4] + pixel[odd0 + 4]) / 4;
			uint8_t B0 = (pixel[evn0 + 2] + pixel[odd0 + 2] + pixel[evn0 + 5] + pixel[odd0 + 5]) / 4;
			uint8_t R1 = (pixel[evn1 + 0] + pixel[odd1 + 0] + pixel[evn1 + 3] + pixel[odd1 + 3]) / 4;
			uint8_t G1 = (pixel[evn1 + 1] + pixel[odd1 + 1] + pixel[evn1 + 4] + pixel[odd1 + 4]) / 4;
			uint8_t B1 = (pixel[evn1 + 2] + pixel[odd1 + 2] + pixel[evn1 + 5] + pixel[odd1 + 5]) / 4;
			uint8_t R = flerpf(R0, R1, xf - (float)x0);
			uint8_t G = flerpf(G0, G1, xf - (float)x0);
			uint8_t B = flerpf(B0, B1, xf - (float)x0);
			add_freq(1500.0 + 800.0 * U_RGB(R, G, B) / 255.0);
		}
	}

	while (add_sample(0.0));
	
	close_pcm(pcm);
	munmap_file(ppm_p, ppm_size);
	return 0;
}