various improvements

playback/cacher.cpp

@@ -206,7 +206,7 @@ void cache_video_worker(Clip* c, long playhead, ClipCache* cache) {
 
 	int i = 0;
 
-	double fr_ratio = qRound((c->sequence->frame_rate / c->frame_rate)*100)*0.01;
+//	double fr_ratio = c->sequence->frame_rate / c->frame_rate;
 
 	/* old swscale solution
 	if (!c->reached_end) {
@@ -231,17 +231,20 @@ void cache_video_worker(Clip* c, long playhead, ClipCache* cache) {
 
 					if (ret >= 0) {
 						// optimization: mathematically determine based on the sequence and clips' frame rates whether this frame will actually be shown
-						double timeline_frame = (i+cache->offset) * fr_ratio;
+						// note: is not actually much faster and currently leads to crashes, may remove in the future
+//						int proposed_frame = qFloor((i+cache->offset) * fr_ratio);
 
-						if (qFloor(timeline_frame) == timeline_frame) {
+//						if (proposed_frame != c->last_cached_frame) {
 							if ((ret = av_buffersrc_add_frame_flags(c->buffersrc_ctx, c->frame, AV_BUFFERSRC_FLAG_KEEP_REF)) < 0) {
 								qDebug() << "[ERROR] Could not feed filtergraph -" << ret;
 								error = true;
 								break;
+//							} else {
+//								c->last_cached_frame = proposed_frame;
 							}
-						} else {
-							i++;
-						}
+//						} else {
+//							i++;
+//						}
 					} else {
 						if (ret == AVERROR_EOF) {
 							c->reached_end = true;
@@ -306,6 +309,8 @@ void reset_cache(Clip* c, long target_frame) {
 				} while (retrieved_frame < target_frame);
 
 				av_frame_free(&temp);
+
+				c->last_cached_frame = -1;
 			} else if (c->stream->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
 				// seek (target_frame represents timeline timecode in frames, not clip timecode)
 				swr_drop_output(c->swr_ctx, swr_get_out_samples(c->swr_ctx, 0));
@@ -367,7 +372,7 @@ void open_clip_worker(Clip* clip) {
 
 		AVDictionary* opts = NULL;
 
-		// decoding optimization configuration
+		// optimized decoding settings
 		if (clip->stream->codecpar->codec_id != AV_CODEC_ID_PNG &&
 			clip->stream->codecpar->codec_id != AV_CODEC_ID_APNG &&
 			clip->stream->codecpar->codec_id != AV_CODEC_ID_TIFF &&