Put frame_diff and pswap into util

1 files changed, 22 insertions, 0 deletions

diff --git a/src/util.c b/src/util.c
index 7b7077d..e642762 100644
--- a/src/util.c
+++ b/src/util.c
@@ -81,6 +81,28 @@ frame_mix(struct video_frame *frame_a, struct video_frame *frame_b)
         }
 }
 
+double
+frame_diff(struct video_frame *frame_a, struct video_frame *frame_b)
+{
+	double average = 0;
+	uint8_t *row_a = frame_a->data, *col_a = NULL;
+	uint8_t *row_b = frame_b->data, *col_b = NULL;
+
+	for (int y = 0; y < frame_a->height; ++y) {
+		col_a = row_a;
+		col_b = row_b;
+		for (int x = 0; x < frame_a->width; ++x) {
+			average += abs(*col_a - *col_b);
+			col_a++;
+			col_b++;
+		}
+		row_a += frame_a->stride;
+		row_b += frame_b->stride;
+	}
+
+	return average / (frame_a->width * frame_a->height);
+}
+
 /* print time in format: "hh:mm:ss.xxx" */
 void
 print_time(int64_t msec) {