Generate a synthetic video signal and use libswscale to perform rescaling.
{
int x, y;
for (x = 0; x <
width; x++)
data[0][y * linesize[0] + x] = x + y + frame_index * 3;
for (y = 0; y <
height / 2; y++) {
for (x = 0; x <
width / 2; x++) {
data[1][y * linesize[1] + x] = 128 + y + frame_index * 2;
data[2][y * linesize[2] + x] = 64 + x + frame_index * 5;
}
}
}
int main(
int argc,
char **argv)
{
uint8_t *src_data[4], *dst_data[4];
int src_linesize[4], dst_linesize[4];
int src_w = 320, src_h = 240, dst_w, dst_h;
const char *dst_size =
NULL;
const char *dst_filename =
NULL;
FILE *dst_file;
int dst_bufsize;
if (argc != 3) {
fprintf(stderr, "Usage: %s output_file output_size\n"
"API example program to show how to scale an image with libswscale.\n"
"This program generates a series of pictures, rescales them to the given "
"output_size and saves them to an output file named output_file\n."
"\n", argv[0]);
exit(1);
}
dst_filename = argv[1];
dst_size = argv[2];
fprintf(stderr,
"Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
dst_size);
exit(1);
}
dst_file = fopen(dst_filename, "wb");
if (!dst_file) {
fprintf(stderr, "Could not open destination file %s\n", dst_filename);
exit(1);
}
if (!sws_ctx) {
fprintf(stderr,
"Impossible to create scale context for the conversion "
"fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
goto end;
}
fprintf(stderr, "Could not allocate source image\n");
goto end;
}
fprintf(stderr, "Could not allocate destination image\n");
goto end;
}
for (
i = 0;
i < 100;
i++) {
sws_scale(sws_ctx, (
const uint8_t *
const*)src_data,
src_linesize, 0,
src_h, dst_data, dst_linesize);
fwrite(dst_data[0], 1, dst_bufsize, dst_file);
}
fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
"ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
end:
fclose(dst_file);
}