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Class: ActiveStorage::Analyzer::VideoAnalyzer

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Analyzer
Instance Chain:
self, Analyzer
Inherits: Analyzer
  • ::Object
Defined in: activestorage/lib/active_storage/analyzer/video_analyzer.rb

Overview

Active Storage Video Analyzer

Extracts the following from a video blob:

  • Width (pixels)
  • Height (pixels)
  • Duration (seconds)
  • Angle (degrees)
  • Display aspect ratio
  • Audio (true if file has an audio channel, false if not)
  • Video (true if file has an video channel, false if not)

Example:

ActiveStorage::Analyzer::VideoAnalyzer.new(blob).metadata
# => { width: 640.0, height: 480.0, duration: 5.0, angle: 0, display_aspect_ratio: [4, 3], audio: true, video: true }

When a video's angle is 90, -90, 270 or -270 degrees, its width and height are automatically swapped for convenience.

This analyzer requires the FFmpeg system library, which is not provided by Rails.

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Class Method Details

.accept?(blob) ⇒ Boolean

[ GitHub ] 

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 25



def self.accept?(blob)
  blob.video?
end


  







Instance Attribute Details



  

    #audio?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 82



def audio?
  audio_stream.present?
end


  








  

    #rotated?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 78



def rotated?
  angle == 90 || angle == 270 || angle == -90 || angle == -270
end


  








  

    #video?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 86



def video?
  video_stream.present?
end


  







Instance Method Details



  

    #angle   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 55



def angle
  if tags["rotate"]
    Integer(tags["rotate"])
  elsif display_matrix && display_matrix["rotation"]
    Integer(display_matrix["rotation"])
  end
end


  








  

    #audio_stream   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 120



def audio_stream
  @audio_stream ||= streams.detect { |stream| stream["codec_type"] == "audio" } || {}
end


  








  

    #computed_height   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 90



def computed_height
  if encoded_width && display_height_scale
    encoded_width * display_height_scale
  end
end


  








  

    #container   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 128



def container
  probe["format"] || {}
end


  








  

    #display_aspect_ratio   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 67



def display_aspect_ratio
  if descriptor = video_stream["display_aspect_ratio"]
    if terms = descriptor.split(":", 2)
      numerator   = Integer(terms[0])
      denominator = Integer(terms[1])

      [numerator, denominator] unless numerator == 0
    end
  end
end


  








  

    #display_height_scale   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 104



def display_height_scale
  @display_height_scale ||= Float(display_aspect_ratio.last) / display_aspect_ratio.first if display_aspect_ratio
end


  








  

    #display_matrix   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 63



def display_matrix
  side_data.detect { |data| data["side_data_type"] == "Display Matrix" }
end


  








  

    #duration   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 50



def duration
  duration = video_stream["duration"] || container["duration"]
  Float(duration) if duration
end


  








  

    #encoded_height   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 100



def encoded_height
  @encoded_height ||= Float(video_stream["height"]) if video_stream["height"]
end


  








  

    #encoded_width   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 96



def encoded_width
  @encoded_width ||= Float(video_stream["width"]) if video_stream["width"]
end


  








  

    #ffprobe_path   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 153



def ffprobe_path
  ActiveStorage.paths[:ffprobe] || "ffprobe"
end


  








  

    #height   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 42



def height
  if rotated?
    encoded_width
  else
    computed_height || encoded_height
  end
end


  








  

    #metadata  
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 29



def metadata
  { width: width, height: height, duration: duration, angle: angle, display_aspect_ratio: display_aspect_ratio, audio: audio?, video: video? }.compact
end


  








  

    #probe   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 132



def probe
  @probe ||= download_blob_to_tempfile { |file| probe_from(file) }
end


  








  

    #probe_from(file)   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 136



def probe_from(file)
  instrument(File.basename(ffprobe_path)) do
    IO.popen([ ffprobe_path,
      "-print_format", "json",
      "-show_streams",
      "-show_format",
      "-v", "error",
      file.path
    ]) do |output|
      JSON.parse(output.read)
    end
  end
rescue Errno::ENOENT
  logger.info "Skipping video analysis because ffprobe isn't installed"
  {}
end


  








  

    #side_data   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 112



def side_data
  @side_data ||= video_stream["side_data_list"] || {}
end


  








  

    #streams   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 124



def streams
  probe["streams"] || []
end


  








  

    #tags   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 108



def tags
  @tags ||= video_stream["tags"] || {}
end


  








  

    #video_stream   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 116



def video_stream
  @video_stream ||= streams.detect { |stream| stream["codec_type"] == "video" } || {}
end


  








  

    #width   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 34



def width
  if rotated?
    computed_height || encoded_height
  else
    encoded_width
  end
end