ffmpeg-ruby

project home on github

Summary

ffmpeg-ruby is a ruby C extension binding to ffmpeg/libav* library.

It's main purpose is to extract frame in order to make video thumbnails. It also give access to main video attributes (frame rate, bit rate, duration, codecs, ...)

So, it doesn't support encoding (at least for now).

Installation

Download latest sources of ffmpeg :

wget http://ffmpeg.mplayerhq.hu/ffmpeg-export-snapshot.tar.bz2
tar xjvf ffmpeg-export-snapshot.tar.bz2
cd ffmpeg-export-20*

Configure, optionally with some prefix :

./configure --prefix=/opt/ffmpeg --enable-pthreads --enable-shared --enable-gpl
make
sudo make install

You can now continue with ffmpeg-ruby.

git clone git://github.com/gwik/ffmpeg-ruby.git

cd ffmpeg-ruby
gem build ./ffmpeg-ruby.gemspec
sudo gem install ./ffmpeg-ruby-0.1.0.gem -- --with-ffmpeg-dir=/opt/ffmpeg

You can now test it :

irb
>> require 'rubygems'
=> false
>> require 'ffmpeg'
=> true
>> FFMPEG
=> FFMPEG

Tutorial

ffmpeg-ruby does not have real document YET (I promise it will change soom). You can take a look a specs for in depth usage.

Here is basic usage.

Video attributes

require 'rubygems'
require 'ffmpeg'

video = FFMPEG::InputFormat.new('alligator.mp4')
=> #<FFMPEG::InputFormat:0x5fa3c0>

video.public_methods - Object.public_instance_methods
=> ["bit_rate", "filename", "duration", "has_stream_with_codec_type?", "first_video_stream", "human_duration", "has_video?", "video_stream_count", "streams", "has_audio?", "first_audio_stream", "audio_stream_count"]

Streams

>> video.first_video_stream.public_methods - Object.public_instance_methods
=> ["position", "duration", "index", "codec", "decode_frame", "seek"]

Seeking in stream

video.first_video_stream.seek(10)
video.first_video_stream.position
=> 10.2333333333333

As you can see, seeking is not very precise.

Extracting frame

frame = video.first_video_stream.decode_frame
=> #<FFMPEG::Frame:0x5c9874>

"frame size #{frame.width}x#{frame.height}"
=> "frame size 240x176"

Animated GIF example with RMagick

See animated_gif_example.rb