New API: exe, @ffmpeg_env, ffmpeg_exe, ffprobe_exe

[asinghvi17]

macro ffmpeg(args)
return quote
withenv(FFMPEG.execenv) do
$(args)
end
end
end

[asinghvi17]

Have tested locally, so I'm pretty sure this branch works. @ianshmean @SimonDanisch any feedback?

[IanButterworth]

How about a slightly shorter set of macros:

@ffmpeg `-version`

@ffprobe `-version`

I guess it would be good to accept both command strings and strings

[IanButterworth]

Also, in the past, ffmpeg output has changed to different std's so VideoIO uses:

function collectexecoutput(exec::Cmd)
    out = Pipe(); err = Pipe()
    p = Base.open(pipeline(ignorestatus(exec), stdout=out, stderr=err))
    close(out.in); close(err.in)
    err_s = readlines(err); out_s = readlines(out)
    return (length(out_s) > length(err_s)) ? out_s : err_s
end

https://github.com/JuliaIO/VideoIO.jl/blob/38131d779e191e72ed9638e1f7053b901f57e087/src/util.jl#L31-L37

Maybe that's worth incorporating into the macros?

[asinghvi17]

Could we do exe(args...; command = FFMPEG.ffmpeg) instead, to leave the macro scene more "pure"? We could then alias ffmpeg(args...) to exe(args...; command = FFMPEG.ffmpeg) and ffprobe(args...) to exe(args...; command = FFMPEG.ffprobe) in a similar way to Homebrew - and have special casing in exe for Cmd literals versus strings.

[IanButterworth]

I like that

[IanButterworth]

Wait, that would mean the ffmpeg namespace would need to be both a variable and function..

[asinghvi17]

Yeah, just realized that :(. The macro thing will be an annoying API in my opinion, though...

[asinghvi17]

Could do fmpeg and fprobe instead? Not the cleanest but it could work for now...or we could just use exe.

Edit: mpeg and probe are also options.

[IanButterworth]

I think dropping an f would be confusing.
How about ffmpeg_exec() etc.

[asinghvi17]

@ianshmean done...

[IanButterworth]

In this new regime, I find the @ffmpeg run(`$ffmpeg -version`) usage little confusing now.
I'd expect @ffmpeg to be limited to the ffmpeg executable. Seems redundant given exe() and ffmpeg_exe() now. Perhaps we drop the macro?

[asinghvi17]

Will do!

Edit: Actually, I'll probably rename it to @ffmpegenv, since not everything can be done by run (like pipelines).