hornetseye-ffmpeg's Introduction

hornetseye-ffmpeg

Author: Jan Wedekind Copyright: 2010, 2011 License: GPL

Synopsis

This Ruby extension defines the class {Hornetseye::AVInput} for reading frames from video files and the class {Hornetseye::AVOutput} for writing frames to video files.

Installation

hornetseye-ffmpeg requires FFMpeg and the software scaling library. If you are running Debian or (K)ubuntu, you can install them like this:

$ sudo aptitude install libavformat-dev libswscale-dev

To install this Ruby extension, use the following command:

$ sudo gem install hornetseye-ffmpeg

Alternatively you can build and install the Ruby extension from source as follows:

$ rake
$ sudo rake install

Usage

Simply run Interactive Ruby:

$ irb

You can load and use FFMpeg as shown below. The example is a simple video player.

require 'rubygems'
require 'hornetseye_ffmpeg'
require 'hornetseye_xorg'
require 'hornetseye_alsa'
include Hornetseye
raise 'Syntax: ./play.rb <video file> [offset]' unless ( 1 .. 2 ).member? ARGV.size
input = AVInput.new ARGV.first
input.pos = ARGV.last.to_i if ARGV.size > 1
display = X11Display.new
output = XVideoOutput.new
w, h = ( input.width * input.aspect_ratio ).to_i, input.height
window = X11Window.new display, output, w, h
window.title = ARGV.first
if input.has_audio?
  alsa = AlsaOutput.new 'default:0', input.sample_rate, input.channels, 16, 1024
  audio_frame = input.read_audio
else
  t0 = Time.new.to_f
end
window.show
while display.status?
  video_frame = input.read_video
  if input.has_audio?
    while alsa.avail >= audio_frame.shape[1]
      alsa.write audio_frame
      audio_frame = input.read_audio
    end
    t = input.audio_pos - alsa.delay.quo( alsa.rate )
  else
    t = Time.new.to_f - t0
  end
  delay = [ input.video_pos - t, 0 ].max
  display.event_loop delay
  output.write video_frame
  display.process_events
end

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