[FFmpeg-devel] PR new filter gltransition

[Rostislav Pehlivanov]

On 29 December 2017 at 08:24, Paul B Mahol <onemda at gmail.com> wrote:

> On 12/29/17, Rostislav Pehlivanov <atomnuker at gmail.com> wrote:
> > On 27 December 2017 at 23:13, Travis Fischer <fisch0920 at gmail.com>
> wrote:
> >
> >> Hello,
> >>
> >> This is my first time contributing to ffmpeg, so please go easy on me :)
> >>
> >> I have a git diff here
> >> <https://github.com/transitive-bullshit/ffmpeg-gl-transition> which
> add a
> >> new filter to apply a GLSL transition between two video streams.  The
> >> github repo for this patch includes all of the relevant documentation
> and
> >> usage examples.
> >>
> >> (sorry, I'm not sure how to formally define the patch, as I'm used to
> just
> >> submitting PRs on github)
> >>
> >> I created this filter because of my frustration with how difficult and
> >> limited the *transition* possibilities were with current concat filter
> >> chains. Anything aside from basic video cross-fades isn't really
> possible.
> >>
> >> After releasing the filter as a standalone extension and seeing some
> other
> >> devs adopt it, I received a lot of feedback that this functionality
> should
> >> be merged info ffmpeg, so I wanted to get the ball rolling and see what
> >> everyone thinks on this list.
> >>
> >> Thanks!
> >> -- Travis Fischer <https://github.com/transitive-bullshit>
> >> _______________________________________________
> >> ffmpeg-devel mailing list
> >> ffmpeg-devel at ffmpeg.org
> >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >>
> >
> > I don't see the point of such a filter. Redundant. We already have a
> > properly implemented OpenCL filter support (and there's a patch to make
> it
> > accept generic kernels). This is a quick hack which requires 2 copies and
> > that's slow and inefficient.
> > Instead, how about a tutorial on how to convert glsl to opencl kernels?
>
> Current OpenCL filters are neither generic nor use framesync.
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>

Which is exactly why I mentioned that in my email. There's a patch which
just needs to be applied.
As for framesync support, the opencl infrastructure is done properly and
init is abstracted enough to be simpler than to use opengl and writing a
filter from scratch.
Not to mention having opengl support in any capacity in lavfi could mess up
any clients using opengl.