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).
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 :
--enable-swscale is mandatory, feel free to add some configuration options
./configure --prefix=/opt/ffmpeg --enable-pthreads --enable-shared --enable-gpl --enable-swscale
make
sudo make install
You can now continue with ffmpeg-ruby.
git checkout 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
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.
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"]
>> video.first_video_stream.public_methods - Object.public_instance_methods
=> ["position", "duration", "index", "codec", "decode_frame", "seek"]
video.first_video_stream.seek(10)
video.first_video_stream.position
=> 10.2333333333333
As you can see, seeking is not very precise.
frame = video.first_video_stream.decode_frame
=> #<FFMPEG::Frame:0x5c9874>
"frame size #{frame.width}x#{frame.height}"
=> "frame size 240x176"
See animated_gif_example.rb