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anonymous /Makefile
Created Jun 6, 2013

What would you like to do?
A simple implementation of an encoder for the Robot36 SSTV mode. It uses jpeglib and sndfile and is just the basic encoder, with no frills.
#
CFLAGS=-I/u0/markv/include -g
LDFLAGS=-L/u0/markv/lib
LIBS=-lsndfile -ljpeg -lm
all: robot36
robot36: robot36.o
$(CC) -o $@ $(LDFLAGS) robot36.o $(LIBS)
#include <stdio.h>
#include <stdlib.h>
#include <complex.h>
#include <math.h>
#include <setjmp.h>
#include <assert.h>
/*
* $Id$
* ___ ___ ___ ___ _____ ____ __
* | _ \/ _ \| _ )/ _ \_ _|__ / / /
* | / (_) | _ \ (_) || | |_ \/ _ \
* |_|_\\___/|___/\___/ |_| |___/\___/
*
* An implementation of a Robot 36 SSTV encoder
* Written by Mark VandeWettering (K6HX)
*/
/* JPEG related headers */
#include <jpeglib.h>
#include <jerror.h>
/* soundfile related headers */
#include <sndfile.h>
#define WIDTH 320
#define HEIGHT 240
#define HALFWIDTH (WIDTH/2)
#define HALFHEIGHT (HEIGHT/2)
typedef float Image[HEIGHT][WIDTH][3] ;
typedef float HalfImage[HALFHEIGHT][HALFWIDTH][3] ;
Image image ;
int
ReadImage(char *fname, Image img)
{
FILE *inp ;
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
int stride, x, y, c, idx ;
JSAMPARRAY buffer ;
if ((inp = fopen(fname, "rb")) == NULL) {
fprintf(stderr, "can't open %s\n", fname);
return 0;
}
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, inp);
(void) jpeg_read_header(&cinfo, TRUE);
(void) jpeg_start_decompress(&cinfo);
if (cinfo.image_width != WIDTH ||
cinfo.image_height != HEIGHT) {
fprintf(stderr, "image size is %dx%d, should be %dx%d.\n",
cinfo.image_width, cinfo.image_height, WIDTH, HEIGHT) ;
return 0 ;
}
/* this would be a programming error if it failed. */
assert(cinfo.output_components == 3) ;
stride = cinfo.output_width * cinfo.output_components;
buffer = (*cinfo.mem->alloc_sarray)
((j_common_ptr) &cinfo, JPOOL_IMAGE, stride, 1);
while (cinfo.output_scanline < cinfo.output_height) {
y = cinfo.output_scanline ;
(void) jpeg_read_scanlines(&cinfo, buffer, 1);
/* copy out the data into the image */
for (x=0, idx=0; x<cinfo.output_width; x++) {
for(c=0; c<3; c++, idx++)
img[y][x][c] = buffer[0][idx]/(float)MAXJSAMPLE ;
}
}
(void) jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(inp);
return 1 ;
}
#define SAMPLERATE 11025
SNDFILE *sf ;
SF_INFO sfinfo ;
complex osc = 0.95 ;
void
blank(float ms)
{
int nsamp = (int) (SAMPLERATE * ms / 1000.) ;
int i ;
float r = 0.0 ;
for (i=0; i<nsamp; i++)
sf_write_float(sf, &r, 1) ;
}
void
pulse(float freq, float ms)
{
/* convert ms to samples */
int nsamp = (int) (SAMPLERATE * ms / 1000.) ;
int i ;
float r ;
complex m = cexp(I*2.0*M_PI*freq / SAMPLERATE) ;
for (i=0; i<nsamp; i++) {
osc *= m ;
r = creal(osc) ;
sf_write_float(sf, &r, 1) ;
}
}
void
Vis(int code)
{
int i ;
pulse(1900, 300.0) ;
pulse(1200, 10.0) ;
pulse(1900, 300.0) ;
pulse(1200, 30.0) ; /* start bit */
for (i=0; i<8; i++) {
if (code & 1)
pulse(1100, 30.0) ;
else
pulse(1300, 30.0) ;
code = code >> 1 ;
}
pulse(1200, 30.0) ; /* stop bit */
}
void
ScanlinePair(Image img, HalfImage halfimg, int y)
{
int i, j ;
int ysamp = 88 * SAMPLERATE / 1000 ;
int samp = 44 * SAMPLERATE / 1000 ;
pulse(1200, 9.0) ; /* sync pulse */
pulse(1500, 3.0) ; /* sync porch */
/* pulse(1600, 88.0) ; */
for (i=0; i<ysamp; i++) {
int idx = i * WIDTH / ysamp ;
float f = 0.0625 + 0.9375 * image[y][idx][0] ;
float freq = 1500.0 + (2300.0-1500.0) * f ;
complex m = cexp(I*2.0*M_PI*freq/SAMPLERATE) ;
osc *= m ;
float r = creal(osc) ;
sf_write_float(sf, &r, 1) ;
}
pulse(1500, 4.5) ; /* even separator pulse */
pulse(1900, 1.5) ; /* porch */
/* pulse(1900, 44.0) ; */
for (i=0; i<samp; i++) {
int idx = i * HALFWIDTH / samp ;
float f = 0.0625 + 0.9375 * halfimg[y/2][idx][1] ;
float freq = 1500.0 + (2300.0-1500.0) * f ;
complex m = cexp(I*2.0*M_PI*freq/SAMPLERATE) ;
osc *= m ;
float r = creal(osc) ;
sf_write_float(sf, &r, 1) ;
}
pulse(1200, 9.0) ; /* sync pulse */
pulse(1500, 3.0) ; /* sync porch */
/* pulse(1600, 88.0) ; */
for (i=0; i<ysamp; i++) {
int idx = i * WIDTH / ysamp ;
float f = 0.0625 + 0.9375 * image[y+1][idx][0] ;
float freq = 1500.0 + (2300.0-1500.0) * f ;
complex m = cexp(I*2.0*M_PI*freq/SAMPLERATE) ;
osc *= m ;
float r = creal(osc) ;
sf_write_float(sf, &r, 1) ;
}
pulse(2300, 4.5) ; /* odd separator pulse */
pulse(1900, 1.5) ; /* porch */
/* pulse(1900, 44.0) ; */
for (i=0; i<samp; i++) {
int idx = i * HALFWIDTH / samp ;
float f = 0.0625 + 0.9375 * halfimg[y/2][idx][2] ;
float freq = 1500.0 + (2300.0-1500.0) * f ;
complex m = cexp(I*2.0*M_PI*freq/SAMPLERATE) ;
osc *= m ;
float r = creal(osc) ;
sf_write_float(sf, &r, 1) ;
}
}
int
main(int argc, char *argv[])
{
char *fname = "wally.jpg" ;
int y, i, j, c ;
HalfImage halfimage ;
if (ReadImage(fname, image))
fprintf(stderr, "%s read successfully.\n", fname) ;
/* downsample */
for (j=0; j<HALFHEIGHT; j++) {
for (i=0; i<HALFWIDTH; i++) {
for (c=0; c<3; c++)
halfimage[j][i][c] =
(image[2*j][2*i][c] +
image[2*j+1][2*i][c] +
image[2*j][2*i+1][c] +
image[2*j+1][2*i+1][c]) / 4.0 ;
}
}
/* now, color space convert */
for (j=0; j<HEIGHT; j++) {
for (i=0; i<WIDTH; i++) {
image[j][i][0] = 0.30 * image[j][i][0] +
0.59 * image[j][i][1] +
0.11 * image[j][i][2] ;
}
}
/* and the half image */
for (j=0; j<HALFHEIGHT; j++) {
for (i=0; i<HALFWIDTH; i++) {
float y = 0.30 * halfimage[j][i][0] +
0.59 * halfimage[j][i][1] +
0.11 * halfimage[j][i][2] ;
halfimage[j][i][1] = (halfimage[j][i][0] - y + 1.0) / 2.0 ;
halfimage[j][i][2] = (halfimage[j][i][2] - y + 1.0) / 2.0 ;
halfimage[j][i][0] = y ;
}
}
sfinfo.channels = 1 ;
sfinfo.samplerate = SAMPLERATE ;
sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16 ;
sf = sf_open("wally.wav", SFM_WRITE, &sfinfo) ;
/* generate the "vis" code. */
blank(500.0) ;
Vis(128+8) ;
for (y=0; y<HEIGHT; y += 2)
ScanlinePair(image, halfimage, y) ;
blank(500.0) ;
sf_close(sf) ;
return 0 ;
}
/*
* $Log$
*/

mucsb commented Aug 7, 2013

I do not know how can I get sndfile and jpeglib. Please help.

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