Class: BbEPUB::Transform::AudioOverlay

Inherits:
Bookbinder::Transform
  • Object
show all
Defined in:
lib/bb-epub/transform/audio_overlay.rb

Overview

EPUB 3 only. Spec:

http://www.idpf.org/epub/301/spec/epub-mediaoverlays.html#sec-package-metadata

Each spine item’s manifest item may have a media-overlay attribute, which is an idref pointing at a SMIL manifest item.

Other properties to manage:

<meta property="media:active-class">-epub-media-overlay-active</meta>
<meta property="media:playback-active-class">-epub-media-overlay-playing</meta>
<meta property="media:duration" refines="#ch1_audio">0:32:29</meta>
<meta property="media:duration">1:36:20</meta>
<meta property="media:narrator">Bill Speaker</meta>

Note: “The Package Document must include the duration of each Media Overlay as well as of the entire Publication.”

Instance Method Summary collapse

Instance Method Details

#dependencies ⇒ Object 



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# File 'lib/bb-epub/transform/audio_overlay.rb', line 21

def dependencies
  [
    BbEPUB::Transform::Metadata,
    BbEPUB::Transform::Resources,
    BbEPUB::Transform::Spine
  ]
end

#from_map(package) ⇒ Object

Create a meta tag for:

audio-overlay-active-class => media:active-class
audio-overlay-playback-active-class => media:playback-active-class
audio-overlay-duration => media:duration
audio-overlay-narrator => media:narrator

For each spine item with a ‘media-overlay’ key:

Find the corresponding map resource
Find the corresponding manifest item for component:
  - set 'media-overlay' to rsrc['id']
Create a top-level meta tag:
  cmpt['audio-overlay-duration'] => meta[property='media:duration'][refines='rsrc["id"]]
Also create a top-level meta tag for media:narrator if cmpt has 'audio-overlay-narrator'



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# File 'lib/bb-epub/transform/audio_overlay.rb', line 119

def from_map(package)
  opf_doc = package.file(:opf).document
  metadata_tag = opf_doc.find('opf|metadata')
  prop_to_meta(
    package.map,
    metadata_tag,
    'audio-overlay-active-class',
    'media:active-class'
  )
  prop_to_meta(
    package.map,
    metadata_tag,
    'audio-overlay-playback-active-class',
    'media:playback-active-class'
  )
  prop_to_meta(
    package.map,
    metadata_tag,
    'audio-overlay-duration',
    'media:duration'
  )
  prop_to_meta(
    package.map,
    metadata_tag,
    'audio-overlay-narrator',
    'media:narrator'
  )
  package.map['spine'].each { |cmpt|
    next  unless cmpt['audio-overlay']
    rsrc = package.map['resources'].detect { |r|
      r['path'] == cmpt['audio-overlay']
    }
    cmpt_manifest_item = opf_doc.find("opf|manifest > opf|item##{cmpt['id']}")
    cmpt_manifest_item['media-overlay'] = rsrc['id']
    duration_meta_tag = prop_to_meta(
      cmpt,
      metadata_tag,
      'audio-overlay-duration',
      'media:duration'
    )
    duration_meta_tag['refines'] = '#'+rsrc['id']
    narrator_meta_tag = prop_to_meta(
      cmpt,
      metadata_tag,
      'audio-overlay-narrator',
      'media:narrator'
    )
    narrator_meta_tag['refines'] = '#'+rsrc['id']  if narrator_meta_tag
  }
end

#to_map(package) ⇒ Object 



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# File 'lib/bb-epub/transform/audio_overlay.rb', line 30

def to_map(package)
  meta_to_prop(
    package,
    'media:active-class',
    'audio-overlay-active-class'
  )
  meta_to_prop(
    package,
    'media:playback-active-class',
    'audio-overlay-playback-active-class'
  )
  book_overlay_duration = meta_to_prop(
    package,
    'media:duration',
    'audio-overlay-duration'
  ) { |hashes|
    hashes.detect { |hash|
      unless hash.has_key?('refines')
        hash['@'] = smil_clock_value_to_seconds(hash['@'])
        true
      end
    }
  }
  # TODO: check that book does have a duration if there are any overlays.
  meta_to_prop(
    package,
    'media:narrator',
    'audio-overlay-narrator'
  ) { |hashes|
    hashes.detect { |hash| !hash.has_key?('refines') }
  }
  # Find each manifest item (SI) with media-overlay attribute:
  #
  #   - find the map['resources'] item that matches the media-overlay id
  #   - find the map['spine'] item that matches the SI id
  #     - set 'audio-overlay' to the AO path
  #     - set 'audio-overlay-duration' to the refined duration
  #     - set 'audio-overlay-narrator' to the refined narrator
  #
  opf_doc = package.file(:opf).document('r')
  opf_doc.each('opf|manifest > opf|item[media-overlay]') { |cmpt_item|
    cmpt_id = cmpt_item['id']
    cmpt = package.map['spine'].detect { |c| c['id'] == cmpt_id }
    # TODO: nil check cmpt
    ao_id = cmpt_item['media-overlay']
    rsrc = package.map['resources'].detect { |r| r['id'] == ao_id }
    # TODO: nil check rsrc
    cmpt['audio-overlay'] = rsrc['path']
    cmpt_overlay_duration = meta_to_prop(
      package,
      'media:duration',
      'audio-overlay-duration',
      cmpt
    ) { |hashes|
      hashes.detect { |hash|
        if hash['refines']['@'] == '#'+ao_id
          hash['@'] = smil_clock_value_to_seconds(hash['@'])
          true
        end
      }
    }
    # TODO: nil check cmpt_overlay_duration
    meta_to_prop(
      package,
      'media:narrator',
      'audio-overlay-narrator',
      cmpt
    ) { |hashes|
      hash['refines']['@'] == '#'+ao_id
    }
  }
end