[FFmpeg-devel] ffmpeg Filtergraph Output

lance.lmwang at gmail.com lance.lmwang at gmail.com
Sun May 24 14:24:16 EEST 2020


On Sun, May 24, 2020 at 02:43:52AM +0000, Soft Works wrote:
> Hello,
> 
> I've seen the commit about the option for dumping the filtergraph and that reminded me about something that I'd be willing to contribute in case anybody likes it.
> 
> A while ago I was looking for a way to get information about the filtergraphs that ffmpeg builds at runtime, the individual formats that have been negotiated between input and output pins and which filters have a hardware context.
> 
> I had expected that this is what the graph2dot is intended to do, but that wasn't the case. Turning a filter string into a graph is not what I was looking for.

By your image, I haven't see big difference with the graph2dot image output. No SAR
info, but with TB info.

> 
> Eventually I have implemented a feature that iterates all filters, their connections and the negotiated media formats during runtime and writes them out as json or xml (using the same methods that ffprobe uses).

I think JSON is difficult to read, graphviz DOT format is good to use and can convert to graph image by graphviz tools.
If you want to dump the graph runtime, avfilter_graph_dump() can be used anyway.

If you think any media format is missing like SAR, we can add it to avfilter_graph_dump().

> 
> I have attached an example output and an image as an example for what could be done with the output.
> 
> Let me know whether there's some interest in this.
> 
> Regards
> Softworkz
> 
> Direct links to the attachments:
> https://gist.github.com/softworkz/4f4bf2c1365d2ce3f6ac70b1b434aa40
> https://github.com/softworkz/ffmpegfiltergraphs/issues/1
> 



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-- 
Thanks,
Limin Wang


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