[FFmpeg-devel] [PATCH] avfilter: add sdlvsink for video display

[Stefano Sabatini]

On date Tuesday 2024-06-11 21:13:48 +0800, Shiqi Zhu wrote:
> On Fri, 7 Jun 2024 at 19:55, Rémi Denis-Courmont <remi at remlab.net> wrote:
> > Le 7 juin 2024 12:53:51 GMT+03:00, Michael Niedermayer <michael at niedermayer.cc> a écrit :
> > >We can require anything from an API that we are able to change and extend
> > >Of course we can decide not to allow such requirment even if optional
> > >but we surely _could_ add such a feature if we choose to do so
> >
> > Sure. You can also require infinite memory or an oracle be provided. That's just not going to happen though. And having libraries depend on the main thread is a well-documented malpractice.
> >
> > I don't think we should add maintenance burden with code that can't be used safely.
> 
> Thank you all for your attention to this patch; I greatly appreciate it.
> 
> I'd like to provide a brief recap of the issue we've been discussing,
> with the following points:
> 
> 1. Addition of sink type in the filter:
> This enhancement is primarily based on the existing avfilter mechanism
> and serves as a strengthening module. Using SDL as the sink doesn't
> seem to be a good fit, as I'll attempt to rectify in the following
> patch.
> https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240611130310.1131755-1-hiccupzhu@gmail.com/
> 
> 2. Utilizing SDL as an implementation for the sink:
> Before submitting the patch, I hadn't considered many aspects. During
> the intense discussions, I retested the patch on different operating
> systems, with the following results, hoping it may assist those
> interested in this issue:
> 
> Command: ./ffmpeg -lavfi
> "testsrc2=size=300x200:rate=25:duration=500,format=yuv420p,sdlvsink"
> -f null /dev/null

In addition to this, I wonder if adding a vsink for each different
output device is the correct way.

We have a movie source which can be used to read from
libavformat/libavdevice, probablhy we should have a movie sink to be
used to write to libavformat/libavdevice, meaning that a single sink
would enable access to all the supported libavformat/libavdevice
outputs.

I started having a look in that direction a looot of time ago. This
was never finalized because I was not sure about ways to pass options
to encoders and muxers, and about dealing with a variable number of
outputs, I'm attaching this very old proof-of-concept patch for
reference.

This approach would be possibly much more complex, but should provide
a single bridge in place of having a different sink for every output
device or muxer.

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