126 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			Ruby
		
	
	
	
			
		
		
	
	
			126 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			Ruby
		
	
	
	
# frozen_string_literal: true
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module Paperclip
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  # This transcoder is only to be used for the MediaAttachment model
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  # to check when uploaded videos are actually gifv's
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  class Transcoder < Paperclip::Processor
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    # This is the H.264 "High" value taken from https://www.dr-lex.be/info-stuff/videocalc.html
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    BITS_PER_PIXEL = 0.11
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    def initialize(file, options = {}, attachment = nil)
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      super
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      @current_format      = File.extname(@file.path)
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      @basename            = File.basename(@file.path, @current_format)
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      @format              = options[:format]
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      @time                = options[:time] || 3
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      @passthrough_options = options[:passthrough_options]
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      @convert_options     = options[:convert_options].dup
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      @vfr_threshold       = options[:vfr_frame_rate_threshold]
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    end
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    def make
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      metadata = VideoMetadataExtractor.new(@file.path)
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      raise Paperclip::Error, "Error while transcoding #{@file.path}: unsupported file" unless metadata.valid?
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      update_attachment_type(metadata)
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      update_options_from_metadata(metadata)
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      destination = Tempfile.new([@basename, @format ? ".#{@format}" : ''])
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      destination.binmode
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      @output_options = @convert_options[:output]&.dup || {}
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      @input_options  = @convert_options[:input]&.dup  || {}
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      case @format.to_s
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      when /jpg$/, /jpeg$/, /png$/, /gif$/
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        @input_options['ss'] = @time
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        @output_options['f']       = 'image2'
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        @output_options['vframes'] = 1
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      when 'mp4'
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        unless eligible_to_passthrough?(metadata)
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          size_limit_in_bits = MediaAttachment::VIDEO_LIMIT * 8
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          desired_bitrate = (metadata.width * metadata.height * 30 * BITS_PER_PIXEL).floor
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          duration = [metadata.duration, 1].max
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          maximum_bitrate = (size_limit_in_bits / duration).floor - 192_000 # Leave some space for the audio stream
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          bitrate = [desired_bitrate, maximum_bitrate].min
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          @output_options['b:v']     = bitrate
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          @output_options['maxrate'] = bitrate + 192_000
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          @output_options['bufsize'] = bitrate * 5
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          if high_vfr?(metadata)
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            @output_options['vsync'] = 'vfr'
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            @output_options['r'] = @vfr_threshold
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          end
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        end
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      end
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      command_arguments, interpolations = prepare_command(destination)
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      begin
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        command = Terrapin::CommandLine.new('ffmpeg', command_arguments.join(' '), logger: Paperclip.logger)
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        command.run(interpolations)
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      rescue Terrapin::ExitStatusError => e
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        raise Paperclip::Error, "Error while transcoding #{@basename}: #{e}"
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      rescue Terrapin::CommandNotFoundError
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        raise Paperclip::Errors::CommandNotFoundError, 'Could not run the `ffmpeg` command. Please install ffmpeg.'
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      end
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      destination
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    end
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    private
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    def prepare_command(destination)
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      command_arguments  = ['-nostdin']
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      interpolations     = {}
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      interpolation_keys = 0
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      @input_options.each_pair do |key, value|
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        interpolation_key = interpolation_keys
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        command_arguments << "-#{key} :#{interpolation_key}"
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        interpolations[interpolation_key] = value
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        interpolation_keys += 1
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      end
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      command_arguments << '-i :source'
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      interpolations[:source] = @file.path
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      @output_options.each_pair do |key, value|
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        interpolation_key = interpolation_keys
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        command_arguments << "-#{key} :#{interpolation_key}"
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        interpolations[interpolation_key] = value
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        interpolation_keys += 1
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      end
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      command_arguments << '-y :destination'
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      interpolations[:destination] = destination.path
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      [command_arguments, interpolations]
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    end
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    def update_options_from_metadata(metadata)
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      return unless eligible_to_passthrough?(metadata)
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      @format          = @passthrough_options[:options][:format] || @format
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      @time            = @passthrough_options[:options][:time]   || @time
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      @convert_options = @passthrough_options[:options][:convert_options].dup
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    end
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    def high_vfr?(metadata)
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      @vfr_threshold && metadata.r_frame_rate && metadata.r_frame_rate > @vfr_threshold
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    end
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    def eligible_to_passthrough?(metadata)
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      @passthrough_options && @passthrough_options[:video_codecs].include?(metadata.video_codec) && @passthrough_options[:audio_codecs].include?(metadata.audio_codec) && @passthrough_options[:colorspaces].include?(metadata.colorspace)
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    end
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    def update_attachment_type(metadata)
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      @attachment.instance.type = MediaAttachment.types[:gifv] unless metadata.audio_codec
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    end
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  end
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end
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