[FFmpeg-devel] Exposing ability to add new filters without recompiling libavfilter?

[Steven Liu]

> On Sep 27, 2024, at 19:22, Carlos Ruiz <carlos.r.domin at gmail.com> wrote:
> 
> Hi all,
> 
> Not sure if this should be directed at libav-user instead, feel free to
> redirect
> me if needed.
> 
> I've read the writing_filters.txt documentation and numerous StackOverflow
> posts and everything indicates that in order to add your own custom filter,
> the
> Makefile in libavfilter needs to modified (and therefore the whole library
> be
> recompiled). Maybe this has been discussed before but I was wondering if
> there are any plans to expose a public API so that downstream users of the
> library could develop and inject their own "local" filters and use them
> inside a
> filter chain together with existing filters.
> 
> For context, we use FFmpeg via Python bindings (PyAV) and I was able to
> wrap my own filter that calls a python callback (so I can use any python
> code
Do you mean you want reference libavfilter/vulkan_glslang.c ?
> to decide what to render on the frame without serializing and interfacing
> with
> c++ directly, which would significantly limit our applications and
> iteration speed).
> I had to use the "private" side of the AVFilter API (nb_inputs, nb_outputs,
> formats)
> and expose the `ff_filter_frame` function, but other than that everything
> works.
> I assume the rationale of not exposing a fully public API is to be able to
> iterate
> quicker without having to maintain backwards compatibility, but there might
> be
> other reasons. In any case, is this something that has ever been proposed
> or are
> there any plans to support extending libavfilter with custom filters
> without having
> to build it from source? Would be super useful to us!
> 
> Thanks,
> Carlos
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