Module: M4S::Dash::Manifest

Extended by:
Manifest
Included in:
Manifest
Defined in:
lib/m4s/dash/manifest.rb

Constant Summary collapse

VIDEO_TRACK = 
'video/mp4'.freeze
AUDIO_TRACK = 
'audio/mp4'.freeze
TRACKS_PRIORITY = 
{ VIDEO_TRACK => 0, AUDIO_TRACK => 1 }.freeze
SCHEMA_LOCATION = 
'urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd'.freeze
PROFILE = 
'urn:mpeg:dash:profile:isoff-live:2011'.freeze

Instance Method Summary collapse

Instance Method Details

#calculate_max_segment_duration(mp4) ⇒ Object 



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# File 'lib/m4s/dash/manifest.rb', line 43

def calculate_max_segment_duration(mp4)
  track = primary_track(mp4)
  max = mp4.max_segment_duration_ticks(track.fetch('track_id')).to_f
  max / track.fetch('timescale').to_f
end

#calculate_media_presentation_duration(mp4) ⇒ Object 



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# File 'lib/m4s/dash/manifest.rb', line 49

def calculate_media_presentation_duration(mp4)
  track = primary_track(mp4)
  mp4.track_sample_delta_sum(track.fetch('track_id')).to_f / track.fetch('timescale')
end

#format_duration(float_seconds) ⇒ Object 



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# File 'lib/m4s/dash/manifest.rb', line 54

def format_duration(float_seconds)
  total_seconds = float_seconds.to_f
  minutes = (total_seconds / 60).to_i
  seconds = total_seconds % 60

  if minutes.positive?
    seconds.positive? ? "PT#{minutes}M#{seconds.round(1)}S" : "PT#{minutes}M"
  else
    "PT#{seconds.round(1)}S"
  end
end

#generate(mp4, init_segment_path:, segment_path:) ⇒ Object 



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# File 'lib/m4s/dash/manifest.rb', line 11

def generate(mp4, init_segment_path:, segment_path:)
  media_presentation_duration = calculate_media_presentation_duration(mp4)
  max_segment_duration = calculate_max_segment_duration(mp4)

  init_template  = join_path(init_segment_path,  'init-$RepresentationID$.mp4')
  media_template = join_path(segment_path,       'chunk-$RepresentationID$-$Number%05d$.m4s')

  builder = Nokogiri::XML::Builder.new(encoding: 'utf-8') do |xml|
    xml.MPD(
      'xmlns:xsi'          => 'http://www.w3.org/2001/XMLSchema-instance',
      'xmlns'              => 'urn:mpeg:dash:schema:mpd:2011',
      'xmlns:xlink'        => 'http://www.w3.org/1999/xlink',
      'xsi:schemaLocation' => SCHEMA_LOCATION,
      'profiles'           => PROFILE,
      'type'               => 'static',
      'mediaPresentationDuration' => format_duration(media_presentation_duration),
      'maxSegmentDuration'        => format_duration(max_segment_duration),
      'minBufferTime'             => format_duration(max_segment_duration * 2.0),
    ) do
      xml.ProgramInformation
      xml.ServiceDescription(id: '0')
      xml.Period(id: '0', start: 'PT0.0S') do
        sorted_tracks(mp4).each_with_index do |track, index|
          render_adaptation_set(xml, mp4, track, index, init_template, media_template)
        end
      end
    end
  end

  builder.to_xml
end