QOImovie - Using QOI format to encode video

This uses the QOI image format to save sequences of images

Tested on M1 macOS, but it should work fine most anywhere.

write a movie

qom *qm = qom_open( "out.qom", "w");
    gfx_canvas *c = gfx_canvas_new(400, 300);
    qom_putframe(qm, c, usec);
qom_close(qm);

write a movie in real time

qom *qm = qom_open( "out.qom", "w");
gfx_canvas *c = gfx_canvas_new(400, 300);
    qom_putframenow(qm, c);
qom_close(qm);

read a movie

qom *qm = qom_open( "out.qom", "r");
for(int frameno = 0; frameno<qom_getnframes(qm); frameno++) {
    double usec;
    gfx_canvas *c = gfx_getframe(qm, frameno, &usec);
    gfx_canvas_free(c);
}
qom_close(qm);

print

qom *qm = qom_open( "out.qom", "r");
qom_print(qm, "test");
qom_close(qm);

To make the program qomutil:

% make

To convert a series of png files into a QOI movie:

% ./qomutil -toqom 00.png 01.png 02.png test.qom

To read images from a QOI movie:

% ./qomutil -topng test.qom outfamily

To print a summary of a QOImovie:

% ./qomutil -print test.qom

To concatenate several .qom files:

% ./qomcat in1.qom in2.qom in3.qom out.qom

To test everything:

# make test

I'm thinking this could be a nice way to store animated icons and UI elements.

Adding multi-resolution support so the movie could be stored in any number of different sizes.

File format may be changing (a tiny bit) in the near future.

All suggestions welcome.