class ActiveStorage::Analyzer::VideoAnalyzer
Extracts the following from a video blob:
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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
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Audio (true if file has an audio channel, false if not)
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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 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, audio: audio?, video: video? }.compact end
Private Instance Methods
angle()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 53 def angle Integer(tags["rotate"]) if tags["rotate"] end
audio?()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 72 def audio? audio_stream.present? end
audio_stream()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 107 def audio_stream @audio_stream ||= streams.detect { |stream| stream["codec_type"] == "audio" } || {} end
computed_height()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 80 def computed_height if encoded_width && display_height_scale encoded_width * display_height_scale end end
container()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 115 def container probe["format"] || {} end
display_aspect_ratio()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 57 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 94 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 duration = video_stream["duration"] || container["duration"] Float(duration) if duration end
encoded_height()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 90 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 86 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 140 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 119 def probe @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 123 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
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 111 def streams probe["streams"] || [] end
video?()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 76 def video? video_stream.present? end
video_stream()
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# File lib/active_storage/analyzer/video_analyzer.rb, line 103 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