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Class: ActiveStorage::Analyzer::VideoAnalyzer

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::ActiveStorage::Analyzer
Instance Chain:
self, ::ActiveStorage::Analyzer
Inherits: ActiveStorage::Analyzer
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 Attribute Summary

::ActiveStorage::Analyzer - Inherited

.analyze_later?

Implement this method in concrete subclasses.

Class Method Summary

::ActiveStorage::Analyzer - Inherited

.accept?

Implement this method in a concrete subclass.
.new

Instance Attribute Summary

::ActiveStorage::Analyzer - Inherited

#blob

Instance Method Summary

::ActiveStorage::Analyzer - Inherited

#metadata

Override this method in a concrete subclass.
#download_blob_to_tempfile

Downloads the blob to a tempfile on disk.
#instrument, #logger, #tmpdir

Constructor Details

This class inherits a constructor from ActiveStorage::Analyzer

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