video-overlay-composition: Optimize premultiplication/unpremultiplication loops

Pull in video frame fields into local variables. Without this the
compiler must assume that they could've changed on every use and read
them from memory again.

This reduces the inner loop from 6 memory reads per pixels to 4, and the
number of writes stays at 3.

diff --git a/gst-libs/gst/video/video-overlay-composition.c b/gst-libs/gst/video/video-overlay-composition.c
index 565c15cb08ed16985001a52251fe2f12e77aa70c..c1d2fcd6dfa27a315fc1f78db9a6afc0a0abc800 100644 (file)
--- a/gst-libs/gst/video/video-overlay-composition.c
+++ b/gst-libs/gst/video/video-overlay-composition.c
@@ -841,12 +841,17 @@ static void
 gst_video_overlay_rectangle_premultiply_0 (GstVideoFrame * frame)
 {
   int i, j;
-  for (j = 0; j < GST_VIDEO_FRAME_HEIGHT (frame); ++j) {
+  int width = GST_VIDEO_FRAME_WIDTH (frame);
+  int height = GST_VIDEO_FRAME_HEIGHT (frame);
+  int stride = GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0);
+  guint8 *data = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
+
+  for (j = 0; j < height; ++j) {
     guint8 *line;
 
-    line = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
-    line += GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0) * j;
-    for (i = 0; i < GST_VIDEO_FRAME_WIDTH (frame); ++i) {
+    line = data;
+    line += stride * j;
+    for (i = 0; i < width; ++i) {
       int a = line[0];
       line[1] = line[1] * a / 255;
       line[2] = line[2] * a / 255;
@@ -860,12 +865,17 @@ static void
 gst_video_overlay_rectangle_premultiply_3 (GstVideoFrame * frame)
 {
   int i, j;
-  for (j = 0; j < GST_VIDEO_FRAME_HEIGHT (frame); ++j) {
+  int width = GST_VIDEO_FRAME_WIDTH (frame);
+  int height = GST_VIDEO_FRAME_HEIGHT (frame);
+  int stride = GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0);
+  guint8 *data = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
+
+  for (j = 0; j < height; ++j) {
     guint8 *line;
 
-    line = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
-    line += GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0) * j;
-    for (i = 0; i < GST_VIDEO_FRAME_WIDTH (frame); ++i) {
+    line = data;
+    line += stride * j;
+    for (i = 0; i < width; ++i) {
       int a = line[3];
       line[0] = line[0] * a / 255;
       line[1] = line[1] * a / 255;
@@ -899,12 +909,17 @@ static void
 gst_video_overlay_rectangle_unpremultiply_0 (GstVideoFrame * frame)
 {
   int i, j;
-  for (j = 0; j < GST_VIDEO_FRAME_HEIGHT (frame); ++j) {
+  int width = GST_VIDEO_FRAME_WIDTH (frame);
+  int height = GST_VIDEO_FRAME_HEIGHT (frame);
+  int stride = GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0);
+  guint8 *data = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
+
+  for (j = 0; j < height; ++j) {
     guint8 *line;
 
-    line = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
-    line += GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0) * j;
-    for (i = 0; i < GST_VIDEO_FRAME_WIDTH (frame); ++i) {
+    line = data;
+    line += stride * j;
+    for (i = 0; i < width; ++i) {
       int a = line[0];
       if (a) {
         line[1] = MIN ((line[1] * 255 + a / 2) / a, 255);
@@ -920,12 +935,17 @@ static void
 gst_video_overlay_rectangle_unpremultiply_3 (GstVideoFrame * frame)
 {
   int i, j;
-  for (j = 0; j < GST_VIDEO_FRAME_HEIGHT (frame); ++j) {
+  int width = GST_VIDEO_FRAME_WIDTH (frame);
+  int height = GST_VIDEO_FRAME_HEIGHT (frame);
+  int stride = GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0);
+  guint8 *data = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
+
+  for (j = 0; j < height; ++j) {
     guint8 *line;
 
-    line = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
-    line += GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0) * j;
-    for (i = 0; i < GST_VIDEO_FRAME_WIDTH (frame); ++i) {
+    line = data;
+    line += stride * j;
+    for (i = 0; i < width; ++i) {
       int a = line[3];
       if (a) {
         line[0] = MIN ((line[0] * 255 + a / 2) / a, 255);