Multi-threaded frame calculation for movie clip proxies

This commit implements multi-threaded calculation of frames
when building proxies. Both scaling and undistortion steps
are now threaded.

Frames and proxy resolution are still handled one-by-one,
saving files after every single step. So if HDD is not so
fast, this commit could have not so much benefit.

Internal changes:

- Added IMB_scaleImBuf_threaded which scales given image
  buffer in multiple threads and uses bilinear filtering.

- libmv's camera intrinsics now have SetThreads() method
  which is used to specify how many OpenMP threads to use
  for buffer distortion/undistortion.

  And yeah, this code is using OpenMP for threading.

- Reshuffled a bit libmv-capi calls and added function
  BKE_tracking_distortion_set_threads to specify number
  of threads used by intrinscis.

2 files changed, 14 insertions, 7 deletions

diff --git a/source/blender/blenkernel/intern/movieclip.c b/source/blender/blenkernel/intern/movieclip.c
index ab42d86152d..1ad0bf1988c 100644
--- a/source/blender/blenkernel/intern/movieclip.c
+++ b/source/blender/blenkernel/intern/movieclip.c
@@ -1244,7 +1244,7 @@ static void movieclip_build_proxy_ibuf(MovieClip *clip, ImBuf *ibuf, int cfra, i
 
 	scaleibuf = IMB_dupImBuf(ibuf);
 
-	IMB_scaleImBuf(scaleibuf, (short)rectx, (short)recty);
+	IMB_scaleImBuf_threaded(scaleibuf, (short)rectx, (short)recty);
 
 	quality = clip->proxy.quality;
 	scaleibuf->ftype = JPG | quality;
diff --git a/source/blender/blenkernel/intern/tracking.c b/source/blender/blenkernel/intern/tracking.c
index 5f8e25af2ee..3100917cd0c 100644
--- a/source/blender/blenkernel/intern/tracking.c
+++ b/source/blender/blenkernel/intern/tracking.c
@@ -1462,6 +1462,8 @@ MovieDistortion *BKE_tracking_distortion_new(void)
 
 	distortion = MEM_callocN(sizeof(MovieDistortion), "BKE_tracking_distortion_create");
 
+	distortion->intrinsics = libmv_CameraIntrinsicsNewEmpty();
+
 	return distortion;
 }
 
@@ -1474,12 +1476,7 @@ void BKE_tracking_distortion_update(MovieDistortion *distortion, MovieTracking *
 	cameraIntrinscisOptionsFromTracking(&camera_intrinsics_options, tracking,
 	                                    calibration_width, calibration_height);
 
-	if (!distortion->intrinsics) {
-		distortion->intrinsics = libmv_CameraIntrinsicsNew(&camera_intrinsics_options);
-	}
-	else {
-		libmv_CameraIntrinsicsUpdate(distortion->intrinsics, &camera_intrinsics_options);
-	}
+	libmv_CameraIntrinsicsUpdate(distortion->intrinsics, &camera_intrinsics_options);
 #else
 	(void) distortion;
 	(void) tracking;
@@ -1488,6 +1485,16 @@ void BKE_tracking_distortion_update(MovieDistortion *distortion, MovieTracking *
 #endif
 }
 
+void BKE_tracking_distortion_set_threads(MovieDistortion *distortion, int threads)
+{
+#ifdef WITH_LIBMV
+	libmv_CameraIntrinsicsSetThreads(distortion->intrinsics, threads);
+#else
+	(void) distortion;
+	(void) threads;
+#endif
+}
+
 MovieDistortion *BKE_tracking_distortion_copy(MovieDistortion *distortion)
 {
 	MovieDistortion *new_distortion;