On Mon, Aug 25, 2014 at 11:29 AM, <ijaureguibe...@lifia.info.unlp.edu.ar> wrote: > > Quoting Dan Dennedy <d...@dennedy.org>: > > > On Mon, Aug 25, 2014 at 8:57 AM, <ijaureguibe...@lifia.info.unlp.edu.ar> > > wrote: > > > >> I'm having a problem with transition composite, blending a PNG image with > >> transparency to a solid background. I'm sending a small C++ program that > >> shows the problem. > >> > >> > > I strongly discourage you from sending custom code when asking for help > > because it is much less convenient than a melt command line or XML. And if > > you do want help with your code, I suggest that you explain the nature of > > your project, whether it is open source, and where to get more information > > about the project and/or its source code. > Ok, sorry about that. Project is unfortunately not open source, not my > choice. Is a project for blending some information (weather and stuff) > on top of live TV shows. > >> >> I set up a multitrack with two tracks and added a composite transition to > >> blend track 1 to track 0. I loaded an image producer for the background and > >> another for the image that blends to the back. While running, looks like > >> colours are wrong. > >> > >> The foreground image has a semitransparent black box that should blend > >> with background. You will notice a violet line 1px wide near the left edge > >> of the box and another green line 1px wide near the right edge of the box. > >> Doing the same composition in GIMP shows no lines in the edges. > >> > >> There is a Makefile to build the example, a c++ source and the 2 images in > >> the attachment. > >> > > > > This looks OK to me. Does it work for you? If not, it might be a bug in > > your version and/or build. > > melt -profile hdv_720_25p 00000001.png -track cancha_1.png -transition > > composite:0/0:100%x100%:100 > > > I know the problems is very subtle. I could reproduce it with the melt > line you sent. I send now two images at 300% zoom, one is made with > melt, the other with GIMP. Here you'll notice that violet line on the > left edge of the big box, and the green on the right edge of the small > box (weather). > > > If it happens with melt, then try the frei0r.composition transition (no > > arguments or properties needed). That will probably give better results and > > performance with RGB sources anyways since it is a RGB effect, while > > composite is a YUV-only effect, more suitable for video sources. > I can give it a try, sure, although I always try to keep dependencies > to a minimum. But going back to the point, should this be considered a > bug?
I see what you are pointing out now. Yes, that is a known artifact as a result of limitations of the current compositor - a combination of chroma subsampling and no interpolation. I am not going to address it as I avoid using it now. Feel free to send a patch. The next version of Shotcut is using frei0r.cairoblend, but there is also frei0r.composition and the affine transition that all provide similar things without the problem. frei0r is not a substantial dependency in my opinion if you are using a build that does not depend on OpenCV. The affine transition adds no dependency. -- +-DRD-+ ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Mlt-devel mailing list Mlt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mlt-devel
