class ActiveStorage::Analyzer::VideoAnalyzer

Extracts the following from a video blob:

Example:

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

When a video's angle is 90 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.

Public Class Methods

accept?(blob) click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 20
def self.accept?(blob)
  blob.video?
end

Public Instance Methods

metadata() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 24
def metadata
  { width: width, height: height, duration: duration, angle: angle, display_aspect_ratio: display_aspect_ratio }.compact
end

Private Instance Methods

angle() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 49
def angle
  Integer(tags["rotate"]) if tags["rotate"]
end
computed_height() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 69
def computed_height
  if encoded_width && display_height_scale
    encoded_width * display_height_scale
  end
end
display_aspect_ratio() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 53
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() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 83
def display_height_scale
  @display_height_scale ||= Float(display_aspect_ratio.last) / display_aspect_ratio.first if display_aspect_ratio
end
duration() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 45
def duration
  Float(video_stream["duration"]) if video_stream["duration"]
end
encoded_height() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 79
def encoded_height
  @encoded_height ||= Float(video_stream["height"]) if video_stream["height"]
end
encoded_width() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 75
def encoded_width
  @encoded_width ||= Float(video_stream["width"]) if video_stream["width"]
end
ffprobe_path() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 113
def ffprobe_path
  ActiveStorage.paths[:ffprobe] || "ffprobe"
end
height() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 37
def height
  if rotated?
    encoded_width
  else
    computed_height || encoded_height
  end
end
probe() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 100
def probe
  download_blob_to_tempfile { |file| probe_from(file) }
end
probe_from(file) click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 104
def probe_from(file)
  IO.popen([ ffprobe_path, "-print_format", "json", "-show_streams", "-v", "error", file.path ]) do |output|
    JSON.parse(output.read)
  end
rescue Errno::ENOENT
  logger.info "Skipping video analysis because FFmpeg isn't installed"
  {}
end
rotated?() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 65
def rotated?
  angle == 90 || angle == 270
end
streams() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 96
def streams
  probe["streams"] || []
end
tags() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 88
def tags
  @tags ||= video_stream["tags"] || {}
end
video_stream() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 92
def video_stream
  @video_stream ||= streams.detect { |stream| stream["codec_type"] == "video" } || {}
end
width() click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 29
def width
  if rotated?
    computed_height || encoded_height
  else
    encoded_width
  end
end