WebVideo¶ ↑

WebVideo allows you to inspect and process video files.

Install¶ ↑

gem 'web_video'

Dependencies¶ ↑

You need install ‘ffmpeg’ liblary and it’s dependent’s…

Linux¶ ↑

Install instructions for Ubuntu: ubuntuforums.org/showthread.php?t=786095

sudo apt-get install ffmpeg
sudo apt-get install libfaac-dev libxvidcore4-dev liba52-0.7.4 liba52-0.7.4-dev libx264-dev
sudo apt-get install libavutil49 libavutil-dev libavcodec-dev
sudo apt-get install libavcodec-unstripped-52

MacOS¶ ↑

sudo port install ffmpeg +lame +libogg +vorbis +faac +faad +xvid +x264 +a52

Logger¶ ↑

You can put it in “config/initializers/web_video.rb”.

logfile = File.open(Rails.root.join('log', 'video.log'), 'w')
logfile.sync = true

WebVideo.logger = Logger.new(logfile)

Usage¶ ↑

Read video information

video = WebVideo::Adapters::FfmpegAdapter.new('demo.avi')

video.filename # => "demo.avi"

video.duration # => "00:03:39.90"

video.bitrate  # => "2624 kb/s"

video.duration_in_seconds # => 219

video.streams  # => Array of streams
  # [ #<WebVideo::Stream @codec="mpeg4", @type="Video", @details="yuv420p, 640x480 [PAR 1:1 DAR 4:3], 30 tbr, 30 tbn, 30 tbc">,
  #   #<WebVideo::Stream @codec="mp3", @type="Audio", @details="44100 Hz, stereo, s16, 128 kb/s">]

Video Convertation

transcoder = WebVideo::Transcoder.new("demo.avi")

or

transcoder = WebVideo::Transcoder.new(video)

Transcoder attributes

transcoder.adapter # => :ffmpeg

transcoder.source  # => return WebVideo::Adapters::FfmpegAdapter instance (video)

Generate flv file. Next example will generate “demo.flv” from “demo.avi”.

options = {:resolution => "480x360"}

begin
  transcoder.convert("demo.flv", options) do |command|
    command << "-ar 22050"
    command << "-ab 128k"
    command << "-acodec libmp3lame"
    command << "-vcodec flv"
    command << "-r 25"
    command << "-y"
  end
rescue WebVideo::CommandLineError => e
  WebVideo.logger.error("Unable to transcode video: #{e.class} - #{e.message}")
end

Generate images from video By default screenshot starts at ‘00:00:01’, to change it pass option :at => ‘00:05:00’ (at five minutes) Or you can pass :at => :center, to get screenshot from video center

transcoder.screenshot("demo.jpg", :resolution => "480x360", :at => :center)

Next code will generate five images: demo_01.jpg, demo_02.jpg, demo_03.jpg …

image_files = 'demo_%2d.jpg'
options = {:resolution => "480x360", :count => 5 }

begin
  transcoder.screenshot(image_files, options) do |command|
    command << "-vcodec mjpeg"
    # The duration for which image extraction will take place
    #command << "-t 4"
    command << "-y"
  end
rescue WebVideo::CommandLineError => e
  WebVideo.logger.error("Unable to transcode video: #{e.class} - #{e.message}")
end

TODO¶ ↑

1. Add adapter for support ‘mencoder’ tool

2. More information about video file (class Stream must parse details)

3. Add support for ‘flvtool2’

4. Write more documentation

5. Write tests

Copyright © 2012 Fodojo, released under the MIT license