On Thursday, July 14, 2016 12:41:20 AM CEST, Dan Dennedy wrote: > Good question, JB :-) > The composite transition gives less image quality for alpha > blending due to subsampled chroma. This also introduces a > 2-pixel precision limitation, which is bad enough on its own but > even worse for animation. I was basically doing some > future-proofing for animation support and to let the user choose > a blending mode, which you can do now by selecting a track and > using Properties. It does support frame threaded parallel > processing, which can help; but currently Shotcut only exposes > that in non-realtime mode (including export). I have not been > happy with performance either, but still Shotcut only has one > track transition choice. So, I chose the one with best quality > and flexibility.
Thanks for your answer Dan. I had a look at frei0r.cairoblend, and one problem is that it always performs an operation to pre-multiply the RGBA input from A frame and B frame, even when the B frame is completely opaque, leading to a large resource consumption. I made a quick test implementing a Qt blend transition in MLT, that turns images into QImage and uses a QPainter to composite. I was able to get a much better performance by checking if the top frame is completely opaque, and querying/processing bottom frame only if there is some transparency (which is not possible with frei0r transitions). My first draft is in my git clone: https://github.com/j-b-m/mlt/commit/87943f5c7b084d57a8c5717126cc0e47462d5ae5 I think it would be a useful addition for multitrack compositing. Any comments / ideas ? regards jb ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports.http://sdm.link/zohodev2dev _______________________________________________ Mlt-devel mailing list Mlt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mlt-devel
