Class: Subconv::CaptionFilter

Inherits:
Object
  • Object
show all
Defined in:
lib/subconv/caption_filter.rb

Overview

Apply post-processing to captions Supported operations:

  • remove color nodes

  • remove flash nodes

  • convert XY viewport relative positions to simple top or bottom positions

  • merge multiple captions on screen at the same time into one caption

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ CaptionFilter

Returns a new instance of CaptionFilter.



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# File 'lib/subconv/caption_filter.rb', line 13

def initialize(options)
  @options = options
  @options[:filter_node_types] ||= []
  @options[:filter_node_types].push ColorNode if @options[:remove_color]
  @options[:filter_node_types].push FlashNode if @options[:remove_flash]
end

Instance Method Details

#process!(captions) ⇒ Object 



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# File 'lib/subconv/caption_filter.rb', line 20

def process!(captions)
  last_timespan = nil
  open_captions = {}
  last_top_position = nil

  captions.map! do |caption|
    is_same_timespan = last_timespan == caption.timespan

    unless is_same_timespan
      # Time changed -> do not compare with previous top position
      last_top_position = nil
      open_captions = {}
    end

    if @options[:xy_position_to_top_or_bottom]
      caption.position = if caption.position.y < 0.5
                           last_top_position = caption.position.y
                           :top
                         elsif !last_top_position.nil? && (caption.position.y - last_top_position) < 0.08
                           # Do not move lines to the bottom when they are continuing directly
                           # from a caption displayed at the top to avoid continuous captions
                           # being thorn in half
                           last_top_position = caption.position.y
                           :top
                         else
                           :bottom
                         end

      # x position is removed altogether and the caption is now center-aligned
      caption.align = :middle
    end

    # Captions are expected to be ordered by increasing timespan and y position (this is
    # guaranteed for the SCC reader)
    if @options[:merge_by_position] && is_same_timespan && open_captions.key?(caption.position)
      target_caption = open_captions[caption.position]
      target_caption.content.children.push TextNode.new("\n")
      target_caption.content.children.concat caption.content.children
      # Remove this caption since it has been merged
      next
    end

    last_timespan = caption.timespan

    open_captions[caption.position] = caption
    caption
  end
  # Remove nils resulting from removed captions
  captions.compact!
  # Do per-caption processing after merging etc.
  captions.each(&method(:process_caption!))
end

#process_caption!(caption) ⇒ Object 



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# File 'lib/subconv/caption_filter.rb', line 73

def process_caption!(caption)
  filter_nodes! caption.content
  merge_text_nodes! caption.content
end