Plots.jl: add a dependency on ffmpeg

[yakir12]

Creating gifs requires ffmpeg. Right now, any test that involves plotting gifs fails on Travis. It would be great to add a dependency on ffmpeg to resolve that problem.

[mkborregaard]

It's Plots philosophy to support functionality for those users who want it, but stay light by not accumulating dependencies. I'd suggest instead checking for ffmpeg availability and generating an appropriate error message with instructions to install it.

[yakir12]

OK. How would one deal with Travis then? I tried adding

addons:
    apt:
        packages:
            - ffmpeg

to .travis.yml but got E: Package 'ffmpeg' has no installation candidate.

[daschw]

Apparently ffmpeg is not in the official ubuntu trusty repositoriers. Maybe this can help you: https://www.faqforge.com/linux/how-to-install-ffmpeg-on-ubuntu-14-04/

[yakir12]

I'll check it out, but surly someone else needed to include tests for gifs in their package?

[yakir12]

OK, I simply don't know how to add ffmpeg to my Travis run, so I've asked on discourse. This is clearly a CI question, not an issue. Maybe the answer to my CI question could be added to the documentation of Plots.

[yakir12]

I'll thus close this now :)

[yakir12]

I'm not sure I know what I'm talking about but:
You know how with some packages after we Pkg.add them, there can come up a sudo request in the REPL about some system-wide install? That would be a pretty cool solution because the user will hardly need to do anything.

[pkofod]

You know how with some packages after we Pkg.add them, there can come up a sudo request in the REPL about some system-wide install? That would be a pretty cool solution because the user will hardly need to do anything.

across platforms?

[yakir12]

right...

[SimonDanisch]

I would recommend to depend on VideoIO, which has ffmpeg as a dependency and tries to install it cross platform... Only issue is, that it doesn't work on 0.6 in a stable way right now... But fixing VideoIO seems to be the right approach for this!

[yakir12]

I agree. But that is a dependency Plots.jl might avoid.

The way I think of this is that this should be an IO issue: Plots create "animations", the user wants to save them as a gif/mp4/webm/wmv etc...

In a way this is similar to the layering PlotRecipes created: a custom module has its own types, you cerate recipes to tell Plots how to plot them, there should be recipes to how to save them (as in IORecipes)...

[SimonDanisch]

That'd be what FileIO does ;) It's just a bit cumversome to hook up ffmpeg!

[mkborregaard]

I'm in favour - maybe just wait for 0.7?