Camera stabilization fixes and improvements

- Nearest interpolation was always used when there's
  no rotation for stabilization. Was a failure of
  optimization heuristic.

- Made 2d stabilization frame acquiring threaded.
  This function is only used for display and sequencer
  which will only benefit of threads here.

- Fixed bug introduced in r48749 which lead to
  re-making stable frame on every redraw.

2 files changed, 30 insertions, 32 deletions

diff --git a/source/blender/blenkernel/intern/movieclip.c b/source/blender/blenkernel/intern/movieclip.c
index c8f3399665c..a83ee548054 100644
--- a/source/blender/blenkernel/intern/movieclip.c
+++ b/source/blender/blenkernel/intern/movieclip.c
@@ -973,6 +973,7 @@ static ImBuf *put_stabilized_frame_to_cache(MovieClip *clip, MovieClipUser *user
 
 	copy_v2_v2(cache->stabilized.loc, tloc);
 
+	cache->stabilized.reference_ibuf = ibuf;
 	cache->stabilized.scale = tscale;
 	cache->stabilized.angle = tangle;
 	cache->stabilized.framenr = framenr;
diff --git a/source/blender/blenkernel/intern/tracking.c b/source/blender/blenkernel/intern/tracking.c
index 9723e65e401..6a7fce4a0a3 100644
--- a/source/blender/blenkernel/intern/tracking.c
+++ b/source/blender/blenkernel/intern/tracking.c
@@ -3564,6 +3564,9 @@ ImBuf *BKE_tracking_stabilize_frame(MovieTracking *tracking, int framenr, ImBuf
 	ImBuf *tmpibuf;
 	float width = ibuf->x, height = ibuf->y;
 	float aspect = tracking->camera.pixel_aspect;
+	float mat[4][4];
+	int j, filter = tracking->stabilization.filter;
+	void (*interpolation)(struct ImBuf *, struct ImBuf *, float, float, int, int) = NULL;
 
 	if (loc)
 		copy_v2_v2(tloc, loc);
@@ -3600,41 +3603,35 @@ ImBuf *BKE_tracking_stabilize_frame(MovieTracking *tracking, int framenr, ImBuf
 		ibuf = scaleibuf;
 	}
 
-	if (tangle == 0.0f) {
-		/* if angle is zero, then it's much faster to use rect copy
-		 * but could be issues with subpixel precisions
-		 */
-		IMB_rectcpy(tmpibuf, ibuf,
-		            tloc[0] - (tscale - 1.0f) * width / 2.0f,
-		            tloc[1] - (tscale - 1.0f) * height / 2.0f,
-		            0, 0, ibuf->x, ibuf->y);
-	}
-	else {
-		float mat[4][4];
-		int i, j, filter = tracking->stabilization.filter;
-		void (*interpolation)(struct ImBuf *, struct ImBuf *, float, float, int, int) = NULL;
-
-		BKE_tracking_stabilization_data_to_mat4(ibuf->x, ibuf->y, aspect, tloc, tscale, tangle, mat);
-		invert_m4(mat);
-
-		if (filter == TRACKING_FILTER_NEAREST)
-			interpolation = nearest_interpolation;
-		else if (filter == TRACKING_FILTER_BILINEAR)
-			interpolation = bilinear_interpolation;
-		else if (filter == TRACKING_FILTER_BICUBIC)
-			interpolation = bicubic_interpolation;
-		else
-			/* fallback to default interpolation method */
-			interpolation = nearest_interpolation;
+	BKE_tracking_stabilization_data_to_mat4(ibuf->x, ibuf->y, aspect, tloc, tscale, tangle, mat);
+	invert_m4(mat);
 
-		for (j = 0; j < tmpibuf->y; j++) {
-			for (i = 0; i < tmpibuf->x; i++) {
-				float vec[3] = {i, j, 0};
+	if (filter == TRACKING_FILTER_NEAREST)
+		interpolation = nearest_interpolation;
+	else if (filter == TRACKING_FILTER_BILINEAR)
+		interpolation = bilinear_interpolation;
+	else if (filter == TRACKING_FILTER_BICUBIC)
+		interpolation = bicubic_interpolation;
+	else
+		/* fallback to default interpolation method */
+		interpolation = nearest_interpolation;
 
-				mul_v3_m4v3(vec, mat, vec);
+	/* This function is only used for display in clip editor and
+	 * sequencer only, which would only benefit of using threads
+	 * here.
+	 *
+	 * But need to keep an eye on this if the function will be
+	 * used in other cases.
+	 */
+    #pragma omp parallel for if(tmpibuf->y > 128)
+	for (j = 0; j < tmpibuf->y; j++) {
+		int i;
+		for (i = 0; i < tmpibuf->x; i++) {
+			float vec[3] = {i, j, 0};
 
-				interpolation(ibuf, tmpibuf, vec[0], vec[1], i, j);
-			}
+			mul_v3_m4v3(vec, mat, vec);
+
+			interpolation(ibuf, tmpibuf, vec[0], vec[1], i, j);
 		}
 	}