Better handing of frames below actual sequence range

When trying to load file below actual sequence range
(like trying to load file for scene frame 10 when clip's
start frame is 20) first frame from file sequence is used.

Before this change first file used to be loaded for every
scene frame below start frame, which polluted memory with
unwanted data.

Now first frame would be loaded only once in this case.

1 files changed, 32 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/movieclip.c b/source/blender/blenkernel/intern/movieclip.c
index 49a64d8e478..d0eb1494451 100644
--- a/source/blender/blenkernel/intern/movieclip.c
+++ b/source/blender/blenkernel/intern/movieclip.c
@@ -357,6 +357,8 @@ typedef struct MovieClipCache {
 		int proxy, filter;
 		short render_flag;
 	} stabilized;
+
+	int sequence_offset;
 } MovieClipCache;
 
 typedef struct MovieClipImBufCacheKey {
@@ -369,6 +371,32 @@ typedef struct MovieClipCachePriorityData {
 	int framenr;
 } MovieClipCachePriorityData;
 
+static int user_frame_to_cache_frame(MovieClip *clip, int framenr)
+{
+	int index;
+
+	index = framenr - clip->start_frame + clip->frame_offset;
+
+	if (clip->source == MCLIP_SRC_SEQUENCE) {
+		if (clip->cache->sequence_offset == -1) {
+			unsigned short numlen;
+			char head[FILE_MAX], tail[FILE_MAX];
+
+			BLI_stringdec(clip->name, head, tail, &numlen);
+
+			/* see comment in get_sequence_fname */
+			clip->cache->sequence_offset = sequence_guess_offset(clip->name, strlen(head), numlen);
+		}
+
+		index += clip->cache->sequence_offset;
+	}
+
+	if (index < 0)
+		return framenr - index;
+
+	return framenr;
+}
+
 static void moviecache_keydata(void *userkey, int *framenr, int *proxy, int *render_flags)
 {
 	MovieClipImBufCacheKey *key = (MovieClipImBufCacheKey *)userkey;
@@ -440,7 +468,7 @@ static ImBuf *get_imbuf_cache(MovieClip *clip, MovieClipUser *user, int flag)
 	if (clip->cache) {
 		MovieClipImBufCacheKey key;
 
-		key.framenr = user->framenr;
+		key.framenr = user_frame_to_cache_frame(clip, user->framenr);
 
 		if (flag & MCLIP_USE_PROXY) {
 			key.proxy = rendersize_to_proxy(user, flag);
@@ -462,7 +490,7 @@ static int has_imbuf_cache(MovieClip *clip, MovieClipUser *user, int flag)
 	if (clip->cache) {
 		MovieClipImBufCacheKey key;
 
-		key.framenr = user->framenr;
+		key.framenr = user_frame_to_cache_frame(clip, user->framenr);
 
 		if (flag & MCLIP_USE_PROXY) {
 			key.proxy = rendersize_to_proxy(user, flag);
@@ -498,9 +526,10 @@ static bool put_imbuf_cache(MovieClip *clip, MovieClipUser *user, ImBuf *ibuf, i
 		                                     moviecache_prioritydeleter);
 
 		clip->cache->moviecache = moviecache;
+		clip->cache->sequence_offset = -1;
 	}
 
-	key.framenr = user->framenr;
+	key.framenr = user_frame_to_cache_frame(clip, user->framenr);
 
 	if (flag & MCLIP_USE_PROXY) {
 		key.proxy = rendersize_to_proxy(user, flag);