ActiveVlc

Do you know VLC, the famous media player ? I'm pretty sure you do ! Do you know this is also a pretty powerfull media processing and streaming framework ? Maybe... Do you understand something about the command line syntax to access vlc's underlying powers ? If you don't this tool is for you !

ActiveVlc provides a simple syntax to configure and run transcoding/streaming/processing operations using VLC. Here's a simple example :

Installation

First and foremost, you must have VLC and libvlc installed on your system and the vlc binary must be in your PATH since we doesn't provide yet a cool configuration system for this (contribution welcomed !)

Add this line to your application's Gemfile:

gem 'activevlc'

And then execute:

$ bundle

Or use the master branch on GitHub to test de development version by replacing the line in your Gemfile by this one:

gem 'activevlc', github: 'elthariel/activevlc'

Or install it yourself as:

$ gem install activevlc

Example

Command line

Let's say you want to read an mp4 file, transcode it using different options, save the result to another file while displaying it to control what's happening. Using the standard vlc's chain syntax you'd have to write

vlc input.mp4 :sout="#transcode{deinterlace, acodec=aac, ab=128, channels=2, vcodec=h264, venc=x264{bpyramid=strict, bframes=4, no-cabac}, vb=512}:duplicate{dst=standard{mux=mp4, dst='output.mp4'}, dst=display}"

Not very readable isn't it ? Let's try the same with ActiveVlc :

AtiveVlc::pipe do
  transcode do
    deinterlace
    audio :aac do
      bitrate 128 # 128 kpbs
      channels 2
    end
    video :h264 do
      encoder :x264 do
        bpyramid :strict
        bframes 4
        cabac false
      end
      bitrate 512 # 512 kbps
    end
  end
  duplicate do
    to :file do
      mux :mp4
      dst 'output.mp4'
    end
    to :display
  end
end

This sintax might be a lot more verbose than the original vlc's one, it is still A LOT more readable and understandable, and since this is plain ruby you can add comment and arbitrary code ! Then you can run it using :

activevlc exec /path/to/the/pipeline.rb input.mp4

From Ruby code

You can also use ActiveVlc programmatically from your ruby code :

def my_encoding_method(input, output)
  # Create the pipeline.
  pipe = ActiveVlc::pipe input do
    transcode do
      # Same syntax as above, also see spec/pipes
    end
    to :file, output
  end

  # Run it synchronously
  ActiveVlc::Runner.new(pipe).run
  # Your transcoding operation is over (except if there were strong errors)
end

Development status

This gem is still under active development althought it might already be usable for many usages.

If you have any trouble, idea or question, please use GitHub issue system. If you have an idea with code attached to it, got to the 'Contributing' section below.

Supported system/rubies

Ruby 1.8 is NOT supported.

This gem is developped using MRI 2.0.0 on Debian 7 / Ubuntu 13.04 but it should work OOB on MRI 1.9 and other GNU/Linux systems.

Altough there might me some threading issues between the interpreter and libvlc, the specs are eported to pass against :

Jruby (1.7)
Rubinius (head) (with some minor problems)

I doesn't have access to any OSX boxes so but it should work as well, please let me know if you encounter any issue.

Usage

Currently, the best documentation is to have a look to the spec (/spec/pipes) or to run the CLI tool to get the embedded help.

Known Issues

We use a pretty ugly hack to be able to run pipelines synchronously
You cannot (yet) configure output(s) from the command line, only with ruby
There's currently almost no error reporting except from the one vlc's outputting on STDOUT. Vlc's logging and error reporting is pretty complex, i still need to take some time to figure it out.

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Write some specs for your feature
Implements your feature and make your test pass
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request