class ActiveStorage::Analyzer::VideoAnalyzer
Extracts the following from a video blob:
-
Width (pixels)
-
Height (pixels)
-
Duration (seconds)
-
Angle (degrees)
-
Display aspect ratio
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 21 def self.accept?(blob) blob.video? end
Public Instance Methods
metadata()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 25 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 51 def angle Integer(tags["rotate"]) if tags["rotate"] end
computed_height()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 71 def computed_height if encoded_width && display_height_scale encoded_width * display_height_scale end end
container()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 102 def container probe["format"] || {} end
display_aspect_ratio()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 55 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 85 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 46 def duration duration = video_stream["duration"] || container["duration"] Float(duration) if duration end
encoded_height()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 81 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 77 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 125 def ffprobe_path ActiveStorage.paths[:ffprobe] || "ffprobe" end
height()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 38 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 106 def probe @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 110 def probe_from(file) IO.popen([ ffprobe_path, "-print_format", "json", "-show_streams", "-show_format", "-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 67 def rotated? angle == 90 || angle == 270 end
streams()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 98 def streams probe["streams"] || [] end
video_stream()
click to toggle source
# File lib/active_storage/analyzer/video_analyzer.rb, line 94 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 30 def width if rotated? computed_height || encoded_height else encoded_width end end