[vlc-devel] [PATCH v2 21/22] opengl: document filters implementation

Alexandre Janniaux ajanni at videolabs.io
Fri Jul 3 10:43:01 CEST 2020


On Thu, Jul 02, 2020 at 07:30:48PM +0300, Rémi Denis-Courmont wrote:
> Le torstaina 2. heinäkuuta 2020, 19.21.02 EEST Alexandre Janniaux a écrit :
> > Hi,
> >
> > The point that I explained in previous patchset is exactly
> > that it can very easily be exposed as a filter_t by exposing
> > a video fliter capability wrapping an instantiation of
> > opengl{filters=MODULE_STRING},
> No. Video filters don't have access to their output, and their output is not
> even necessarily a display plugin. You can't simply "wrap" them.

I'm not sure what you mean, I need neither of the two point
you mention, and since we have it working for a long time,
I fail to see why tell me that it's not possible.

> And then filters (or VLC in general) can't do introspection nor reflection, so
> they can't simply "pass on" arbitrary parameters.

We don't need this too also, where does it come from?

> (...)
> > Since years, the OpenGL doesn't handle the input format,
> > glconv modules did and glinterop are doing it now. Here the
> > hardware-accelerated filter will be the video filter "opengl"
> > but not necessarily "opengl filter" modules directly.
> ... because it never had to, because it never had filters. "Since years", VDPAU
> (and probably some other opaque formats) have had filters operating on, well,
> opaque formats - with the conversion from CPU bitmaps handled by conversion
> filters.

Why would we need it right now?

> This is not exactly a ground-breaking discovery. Laurent already was
> considering how to map OpenGL and DX filters when designing the "new" video
> output - like a decode. Conclusion was that you can either do it like VDPAU
> does now, or through a combination of video format and VOUT_CHANGE control.
> The later obviously does not scale up.

I'm not sure of what you're talking of, do you have an
approximate date/month/year that I could be picking from the
mailing list or some documentation?

Alexandre Janniaux

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