You could stream the images in a video encoder directly.
For example you can feed ffmpeg with raw PGM/PPM images as input and you will get the compressed video as output without the need to ever create the actual images on disk.
Writing a PGM or PPM image means just generating a few header bytes followed by actual pixel values and thus is trivial to do with any language without the need of any image library. For example:
#include <stdio.h>
#include <math.h>
#include <algorithm>
int main(int argc, const char *argv[]) {
int w = 1920, h = 1080;
for (int frame=0; frame<100; frame++) {
// output frame header
printf("P5\n%i %i 255\n", w, h);
for (int y=0; y<h; y++) {
for (int x=0; x<w; x++) {
double dx = (x - w/2),
dy = (y - h/2),
d = sqrt(dx*dx + dy*dy),
a = atan2(dy, dx) - frame*2*3.14159265359/100,
value = 127 + 127*sin(a+d/10);
// output pixel
putchar(std::max(0, std::min(255, int(value))));
}
}
}
return 0;
}
generates on standard output a sequence of images that can be combined in a video directly. Running the program with
./video | ffmpeg -i - -r 60 -format pgm -y out.mp4
will generate a video named out.mp4. The video will be at 60fps (what -r is for) created from source images in PGM format (-format pgm) from standard input (option -i -) overwriting the output file if it's already present (-y).
This code was tested on linux; for this approach to work on windows you need also to set stdout to binary more with _setmode(fileno(stdout), _O_BINARY); or something similar (I didn't test on windows).
A more sophisticated way to do basically the same would be to start a child process instead of using piping thus leaving standard output usable by the program.
