class ActiveStorage::Analyzer::VideoAnalyzer
Extracts the following from a video blob:
-
Width (pixels)
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Height (pixels)
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Duration (seconds)
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Angle (degrees)
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Display aspect ratio
Example:
ActiveStorage::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)
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# File lib/active_storage/analyzer/video_analyzer.rb, line 23 def self.accept?(blob) blob.video? end
Public Instance Methods
metadata()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 27 def metadata { width: width, height: height, duration: duration, angle: angle, display_aspect_ratio: display_aspect_ratio }.compact end
Private Instance Methods
angle()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 52 def angle Integer(tags["rotate"]) if tags["rotate"] end
computed_height()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 72 def computed_height if encoded_width && display_height_scale encoded_width * display_height_scale end end
display_aspect_ratio()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 56 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()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 86 def display_height_scale @display_height_scale ||= Float(display_aspect_ratio.last) / display_aspect_ratio.first if display_aspect_ratio end
duration()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 48 def duration Float(video_stream["duration"]) if video_stream["duration"] end
encoded_height()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 82 def encoded_height @encoded_height ||= Float(video_stream["height"]) if video_stream["height"] end
encoded_width()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 78 def encoded_width @encoded_width ||= Float(video_stream["width"]) if video_stream["width"] end
ffprobe_path()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 116 def ffprobe_path ActiveStorage.paths[:ffprobe] || "ffprobe" end
height()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 40 def height if rotated? encoded_width else computed_height || encoded_height end end
probe()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 103 def probe download_blob_to_tempfile { |file| probe_from(file) } end
probe_from(file)
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# File lib/active_storage/analyzer/video_analyzer.rb, line 107 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?()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 68 def rotated? angle == 90 || angle == 270 end
streams()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 99 def streams probe["streams"] || [] end
video_stream()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 95 def video_stream @video_stream ||= streams.detect { |stream| stream["codec_type"] == "video" } || {} end
width()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 32 def width if rotated? computed_height || encoded_height else encoded_width end end