FFmpegPipe.jl - Save videos from Julia

FFmpegPipe lets you read/write video files (mp4, wmv, avi, mov...) from Julia by piping images from/to an FFmpeg process.

This is neither as efficient nor as versatile as calling lower-level routines from libav/ffmpeg directly, like VideoIO.jl does, but that package does not yet support video output.

Anything that Julia can show as a MIME("image/png") can be sent as a video frame, in particular Plot objects from Plots.jl and Array{T,2} where T<:Colorant from Images.jl have been tested to work. (Yes, it is unnecessary to compress/decompress a PNG image only to pass it form one process to another, but at least it is lossless.)

Examples

We can create a movie by generating lots of plots and writing each one to the movie as a frame.

Plots.jl and FFmpeg must already be installed, or this will not work.

using FFmpegPipe
using Plots
s = openvideo("sinecurve.mp4", "w", r=24)
pyplot()
for a in linspace(0, pi, 3*24)
    x = a+linspace(0, pi, 1000)
    plt = plot(x, sin.(x))
    writeframe(s, plt)
end
close(s)

We can apply an effect by reading frames from one move and writing modified frames to another movie. However, all information except the images themselves (sound, subtitles, framerate, metadata...) will need to be transfered to the new movie in some other way.

s1 = openvideo("sinecurve.mp4", "r")
s2 = openvideo("upsidecurve.mp4", "w", r=24)
while !eof(s1)
    img = readframe(s1)
    writeframe(s2, img[end:-1:1,:])
end
close(s2)
close(s1)

Note

This is just a simple wrapper. The author of this package is not affiliated with the authors of FFmpeg in any way.

FFmpeg is a trademark of Fabrice Bellard, originator of the FFmpeg project.