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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 theFFmpeg 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 30



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 87



def audio?
  audio_stream.present?
end


  








  

    #rotated?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 83



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 91



def video?
  video_stream.present?
end


  







Instance Method Details



  

    #angle   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 60



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 125



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 95



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 133



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


  








  

    #display_aspect_ratio   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 72



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 109



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 68



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 55



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 105



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 101



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 159



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


  








  

    #height   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 47



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 34



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 137



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 141



def probe_from(file)
  instrument(File.basename(ffprobe_path)) do
    IO.popen([ ffprobe_path,
      "-print_format", "json",
      "-show_streams",
      "-show_format",
      "-v", "error",
      *Shellwords.split(ActiveStorage.ffprobe_arguments),
      file.path
    ]) do |output|
      JSON.parse(output.read, allow_duplicate_key: true)
    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 117



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


  








  

    #streams   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 129



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


  








  

    #tags   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 113



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


  








  

    #video_stream   (private)
  

  [ GitHub ]


  

  


# File 'activestorage/lib/active_storage/analyzer/video_analyzer.rb', line 121



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 39



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