Class: Aspera::Preview::Generator

Inherits:
Object
  • Object
show all
Defined in:
lib/aspera/preview/generator.rb

Overview

Generates one preview file for one format for one file at a time.

Constant Summary collapse

PREVIEW_FORMATS =

Values for preview_format: output format.

%i[png mp4].freeze
FFMPEG_OPTIONS_LIST =

List of valid ffmpeg option keys for reencode configuration.

%w[in out].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(src, dst, options, main_temp_dir, mime: nil) ⇒ Generator

Node API MIME types are from: svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types. The resulting preview file type is taken from destination file extension. Conversion methods are provided by private methods: convert_<conversion_type>to<preview_format>.

-> conversion_type is one of FileTypes::CONVERSION_TYPES.
-> preview_format is one of Generator::PREVIEW_FORMATS.

The conversion video->mp4 is implemented in methods: convert_video_to_mp4_using_<video_conversion>.

-> conversion method is one of Generator::VIDEO_CONVERSION_METHODS.

Parameters:

  • src (String) —

    Source file path.

  • dst (String) —

    Destination file path.

  • options (Options) —

    All conversion options.

  • main_temp_dir (String) —

    Main temp folder, sub folder will be created for generation.

  • mime (String, nil) (defaults to: nil) —

    Optional MIME type as provided by node api (or nil).



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# File 'lib/aspera/preview/generator.rb', line 39

def initialize(src, dst, options, main_temp_dir, mime: nil)
  # Source file path
  @source = src
  # Destination file path
  @destination = dst
  @options = options
  # temp folder name based on source file
  @temp_folder = File.join(main_temp_dir, @source.split('/').last.gsub(/\s/, '_').gsub(/\W/, ''))
  # Extract preview format from extension of target file.
  @preview_format_sym = File.extname(@destination).gsub(/^\./, '').to_sym
  conversion_type = FileTypes.instance.conversion_type(@source, mime)
  @processing_method = "convert_#{conversion_type}_to_#{@preview_format_sym}"
  if conversion_type.eql?(:video)
    case @preview_format_sym
    when :mp4
      @processing_method = "#{@processing_method}_using_#{@options.video_conversion}"
    when :png
      @processing_method = "#{@processing_method}_using_#{@options.video_png_conv}"
    end
  end
  @processing_method = @processing_method.to_sym
  Log.log.debug{"method: #{@processing_method}"}
  Aspera.assert(respond_to?(@processing_method, true)){"no processing known for #{conversion_type} -> #{@preview_format_sym}"}
  command = [:magick] + %w[identify -list font]
  magick_fonts = Utils.parse_magick_fonts(Utils.execute(*command, mode: :capture).first)
  Aspera.assert(magick_fonts[:fonts].any?{ |f| f[:name].eql?(@options.thumb_text_font)}){"Missing font #{@options.thumb_text_font} in #{command}"}
end

Instance Attribute Details

#conversion_type ⇒ Object (readonly)

CLI needs to know conversion type to know if need skip it. One of CONVERSION_TYPES.



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# File 'lib/aspera/preview/generator.rb', line 25

def conversion_type
  @conversion_type
end

#destination ⇒ Object (readonly)

CLI needs to know conversion type to know if need skip it. One of CONVERSION_TYPES.



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# File 'lib/aspera/preview/generator.rb', line 25

def destination
  @destination
end

Instance Method Details

#error_asset ⇒ String

Path to error image corresponding to preview type.

Returns:

  • (String) —

    The path to the error image.



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# File 'lib/aspera/preview/generator.rb', line 82

def error_asset
  File.expand_path(@preview_format_sym.eql?(:mp4) ? 'video_error.png' : 'image_error.png', File.dirname(__FILE__))
end

#generate ⇒ Object

Creates preview as specified in constructor.



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# File 'lib/aspera/preview/generator.rb', line 68

def generate
  Log.log.debug{"#{@source}->#{@destination} (#{@processing_method})"}
  begin
    send(@processing_method)
    # Check that generated size does not exceed maximum.
    result_size = File.size(@destination)
    Log.log.warn{"preview size exceeds maximum allowed #{result_size} > #{@options.max_size}"} if result_size > @options.max_size
  ensure
    FileUtils.rm_rf(@temp_folder)
  end
end