Initial push

Makefile

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+all: compile
+
+compile:
+	gcc frames2img.c -o frames2img -lpng -fopenmp
+
+clean:
+	-rm frames2img

frames2img.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <png.h>
+#include <omp.h>
+
+typedef uint8_t uint8;
+typedef uint32_t uint32;
+
+const int bytesPerPixel = 3; /// red, green, blue
+
+void usage();
+uint32 averagergb(png_image *, uint8 *);
+
+int main(int argc, char **argv){
+	if(argc == 1) usage();
+	char *imageFileName = "output.png";
+	int height = 720;
+	int width = argc-1;
+	int percent = 0;
+
+	uint32 frames[width];
+
+#pragma omp parallel for
+	for(int i =1;i<argc;i++) {
+		png_image image = {.version = PNG_IMAGE_VERSION, .opaque = NULL, };
+		if(!png_image_begin_read_from_file(&image, argv[i])) usage();
+		image.format = PNG_FORMAT_RGB;
+
+		uint8 *buffer = malloc(PNG_IMAGE_SIZE(image));
+
+		png_image_finish_read(&image, NULL, buffer, 0, NULL);
+
+		frames[i-1] = averagergb(&image, buffer);
+
+		free(buffer);
+		png_image_free(&image);
+
+		fprintf(stdout, "%d%% Complete\r", ++percent * 100 / argc);
+		fflush(stdout);
+	}
+	uint8 image[height][width][bytesPerPixel];
+
+	for(int i=0; i<height; i++){
+		for(int j=0; j<width; j++){
+			image[i][j][2] = ((frames[j] >> 16)&0xff);
+			image[i][j][1] = ((frames[j] >> 8)&0xff);
+			image[i][j][0] = (frames[j] & 0xff);
+		}
+	}
+
+	png_image output = {0};
+	output.format = PNG_FORMAT_RGB;
+	output.version = PNG_IMAGE_VERSION;
+	output.width = width;
+	output.height = height;
+
+	png_image_write_to_file(&output, imageFileName, 0, image, 0, NULL);
+}
+
+void
+usage() {
+	fprintf(stderr, "USAGE: ./frames2img PNGs...");
+	exit(1);
+}
+
+uint32
+averagergb(png_image *img, uint8 *buffer) {
+	png_image image = *img;
+	double sumR = 0;
+	double sumG = 0;
+	double sumB = 0;
+
+	double fact = image.width * image.height;
+
+	for(int y =0;y<image.height;y++) {
+		for(int x=0;x<image.width;x++) {
+			sumR += buffer[3*(x+y*image.width)+2] / fact;
+			sumG += buffer[3*(x+y*image.width)+1] / fact;
+			sumB += buffer[3*(x+y*image.width)+0] / fact;
+		}
+	}
+
+	return (((uint8) sumR & 0xff) << 16) |
+		(((uint8)sumG & 0xff) << 8) |
+		((uint8) sumB & 0xff);
+}