On Mon, Nov 14, 2011 at 12:23 PM, Christophe Thommeret <[email protected]> wrote: > Hi, > > First, thanx for this great work, I'm using MLT with the Kdenlive frontend to > edit video (mainly avchd) and it does its job quite well. > But even with low res video (i use kdenlive's "proxy clip" feature), adding a > simple effect like contrast makes the preview to drop frames. I sure don't > have > the strongest cpu around but i think a E8500 is not so bad. > I've recently played a bit with opengl and found that a simple nvidia GT220 > can run several glsl filters (say 6, like contrast,brightness...) on a > 1920x1080, while still displaying 50fps (deinterlaced 25i) ! So you can > imagine what could be done on lowres ! > Having a flawless preview is really comfortable :) > > I see that opengl is in MLT's todo. So i wonder if you have already some > thoughts on what should be done and how it should be done. > I would be happy to help.
There is already a WebVfx plugin that supports GLSL via JS in QtWebKit's WebGL. Recently, I added a shader for YCbCr-to-RGB color conversion for the OpenGL output in a new project I am working on, and I see its benefit. In general, it seems difficult and costly performance-wise to fit GPU effects into the framework unless you use them entirely. Otherwise, you end having to do some on the CPU and also keep the full flexibility and expression of arbitrary filter ordering. Also, one should consider OpenCL and how either can be combined with hwaccel decoder output in vendor-independent VA-API, which is still not integrated. I am not willing to lend much effort to a NVIDIA-only solution. Also, my experience with VDPAU shows it gets tricky to keep things stable when you combine it with multiple video tracks, transitions, and parallel processing, which is why it is not enabled by default. I am slowly learning more about where I want to go with this, but not aggressively. Feel free to contribute. You might want to contribute VA-API integration or improve upon VDPAU to get started. Once you want to move into filters, we will need an image type to represent a surface or PBO and its converters with the other image types. -- +-DRD-+ ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Mlt-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mlt-devel
