Created attachment 119145 [details] video showing the bug Please see attached video. STEPS TO REPRODUCE 1. Create two color clips of different colors. 2. Drag the two color clips to neighboring video tracks on the timeline, partially overlapping in time. 3. Add the "Composite and transform" composition between the two clips. (you don't even have to change any settings) 3. Play the project. OBSERVED RESULT When the playback cursor hits the composition, playback slows down considerably. Note that sometimes the speed will be fine during the first playback, but slow on subsequent playbacks. Even if the playback speed is correct the first time, the transition is still very choppy, even on my 6-core i7. EXPECTED RESULT Playback should not slow down. SOFTWARE/OS VERSIONS Kdenlive: 19.03.80 (kdenlive-19.03.80-674b5d3-x86_64.appimage) OS: KDE neon 5.15 User Edition KDE Plasma Version: 5.15.3 KDE Frameworks Version: 5.56.0 Qt Version: 5.12.0 CPU: Intel Core i7-990x Bloomfield (3.46 GHz hexa-core, Socket 1366) RAM: 12GB DDR3 Video: EVGA NVIDIA GeForce GTX 980 Ti SC (GAMING ACX 2.0+?) w/ 6GB RAM (PCI Express) NVIDIA video driver: 415.27
I can still reproduce this bug using the latest nightly, kdenlive-20.03.70-e76198a-x86_64.appimage.
If you use the actual nightly build: Goto Monitor -> Preview resolution -> choose either 720p or 540p. This should speed up the composition and effect playing.
I can not reproduce using version 20.12.3. Please update and test again. If you still have problems please consider to try the preview scaling (described in @emohr's comment above) and give some feedback or close this bug report if it is solved
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I can confirm that this bug no longer occurs in current versions of Kdenlive (20.12.3 here). Resolving as fixed.