glitchier-soc/lib/paperclip/transcoder.rb

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