ScreenRecorder

A Ruby gem to video record or take screenshots of your computer screen - desktop or specific window - using FFmpeg. Primarily geared towards recording automated UI (Selenium) test executions for debugging and documentation.

Demo

https://kapoorlakshya.github.io/introducing-screen-recorder-ruby-gem

Compatibility

Works on Windows, Linux, and macOS. Requires Ruby 2.0+ or JRuby 9.2+.

Installation

1. Setup FFmpeg

Linux and macOS instructions are here.

macOS: Follow these steps to avoid issues related to Privacy settings.

For Microsoft Windows, download the binary from here. Once downloaded, add location of the ffmpeg/bin folder to the PATH environment variable (instructions).

Alternatively, you can point to the binary file using ScreenRecorder.ffmpeg_binary = '/path/to/ffmpeg' in your project.

2. Install gem

Next, add these lines to your application's Gemfile:

gem 'ffi' # Windows only
gem 'screen-recorder', '~> 1.0'

The ffi gem is used by the childprocess gem on Windows, but it does not explicitly require it. More information on this here.

And then execute:

$ bundle

Or install it yourself as:

$ gem install ffi # Windows only
$ gem install screen-recorder

3. Require gem

require 'screen-recorder'

Usage

Record Desktop

@recorder = ScreenRecorder::Desktop.new(output: 'recording.mkv')
@recorder.start

# Run tests or whatever you want to record

@recorder.stop

Linux and macOS users can optionally provide a display or input device number. Read more about it in the wiki here.

Record Application Window (Microsoft Windows only)

require 'watir'

browser   = Watir::Browser.new :firefox
@recorder = ScreenRecorder::Window.new(title: 'Mozilla Firefox', output: 'recording.mkv')
@recorder.start

# Run tests or whatever you want to record

@recorder.stop
browser.quit 

This mode has a few limitations which are listed in the wiki here.

Fetch Title

A helper method is available to fetch the title of the active window for the given process name.

ScreenRecorder::Window.fetch_title('firefox') # Name of exe
#=> ["Mozilla Firefox"]

ScreenRecorder::Window.fetch_title('chrome')
#=> ["New Tab - Google Chrome"]

Capture Audio

Provide the following advanced configurations to capture audio:

# Linux
advanced = { f: 'alsa', ac: 2, i: 'hw:0'} # Using ALSA
# Or using PulseAudio 
advanced = { 'f': 'pulse', 'ac': 2, 'i': 'default' } # Records default sound output device 

# macOS
advanced = { input: { i: '1:1' } } # -i video:audio input device ID

# Windows
advanced = { f: 'dshow', i: 'audio="Microphone (Realtek High Definition Audio)"' }

You can retrieve a list of audio devices by running these commands:

# Linux
$ arecord -L # See https://trac.ffmpeg.org/wiki/Capture/ALSA

# macOS
$ ffmpeg -f avfoundation -list_devices true -i ""

# Windows
> ffmpeg -list_devices true -f dshow -i dummy

Screenshots

Screenshots can be captured at any point after initializing the recorder:

# Desktop
@recorder = ScreenRecorder::Desktop.new(output: 'recording.mkv')
@recorder.screenshot('before-recording.png')
@recorder.start
@recorder.screenshot('during-recording.png')
@recorder.stop
@recorder.screenshot('after-recording.png')

# Window (Microsoft Windows only)
browser   = Watir::Browser.new :chrome, options: { args: ['--disable-gpu'] } # Hardware acceleration must be disabled
browser.goto('watir.com')
window_title = ScreenRecorder::Window.fetch_title('chrome').first
@recorder = ScreenRecorder::Window.new(title: window_title, output: 'recording.mkv')
@recorder.screenshot('before-recording.png')
@recorder.start
@recorder.screenshot('during-recording.png')
@recorder.stop
@recorder.screenshot('after-recording.png')
browser.quit 

Video Output

Once the recorder is stopped, you can view the video metadata or transcode it if desired.

@recorder.video
=> #<FFMPEG::Movie:0x0000000004327900 
        @path="recording.mkv", 
        @metadata={:streams=>[{:index=>0, :codec_name=>"h264", :codec_long_name=>"H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10", 
        :profile=>"High", 
        :codec_type=>"video"} 
        @video_codec="h264", 
        @colorspace="yuv420p", 
        ... >

@recorder.video.transcode("recording.mp4") { |progress| puts progress } # 0.2 ... 0.5 ... 1.0

See streamio-ffmpeg gem for more details.

Discard Recording

If your test passes or you do not want the recording for any reason, simply call @recorder.discard or @recorder.delete to delete the video file.

Advanced Options

You can provide additional parameters to FFmpeg using the advanced parameter. You can specify input/output specific parameters using input: {} and output: {} within the advanced Hash.

advanced = {
  input:    {
    framerate:  30,
    pix_fmt:    'yuv420p',
    video_size: '1280x720'
  },
  output:   {
    r:       15, # Framerate
    pix_fmt: 'yuv420p'
  },
  log:      'recorder.log',
  loglevel: 'level+debug', # For FFmpeg
}
ScreenRecorder::Desktop.new(output: 'recording.mkv', advanced: advanced)

This will be parsed as:

ffmpeg -y -f gdigrab -framerate 30 -pix_fmt yuv420p -video_size 1280x720 -i desktop -r 15 pix_fmt yuv420p -loglevel level+debug recording.mkv

Logging & Debugging

You can configure the logging level of the gem to troubleshoot problems:

ScreenRecorder.logger.level = :DEBUG

Also refer to the ffmpeg.log file for details.

Use with Cucumber

A Cucumber + Watir based example is available here.

Wiki

Please see the wiki for solutions to commonly reported issues.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec rake to run the tests and rubocop. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Contributing

Bug reports and pull requests are welcome.

• Please update the specs for your code changes and run them locally with bundle exec rake spec.
• Follow the Ruby style guide and format your code - https://github.com/rubocop-hq/ruby-style-guide

License

The gem is available as open source under the terms of the MIT License.

Credits

Thanks to Denys Bazarnyi for testing macOS compatibility in v1.1.0.

This gem relies on the streamio-ffmpeg gem to extract metadata from the output file.

Thanks to SauceLabs for providing me with a free account. If you manage an open source project, you can apply for a free account here.