Class: WebVTT::Segmenter

Inherits:
Object
  • Object
show all
Defined in:
lib/webvtt/segmenter.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(webvtt, options = {}) ⇒ Segmenter

Returns a new instance of Segmenter.



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# File 'lib/webvtt/segmenter.rb', line 22

def initialize(webvtt, options={})
  @webvtt = webvtt
  @options = options
  @options[:length] ||= 10
  @options[:output] ||= "fileSequence-%05d.vtt"
  @options[:playlist] ||= "prog_index.m3u8"
end

Instance Attribute Details

#webvtt ⇒ Object (readonly)

Returns the value of attribute webvtt.



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# File 'lib/webvtt/segmenter.rb', line 20

def webvtt
  @webvtt
end

Instance Method Details

#find_segment_files(cue) ⇒ Object 



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# File 'lib/webvtt/segmenter.rb', line 30

def find_segment_files(cue)
  seg = find_segments(cue)

  # we need to find out how many segments we
  # have to remove from our calculation
  # in the case of first cue not starting at 0
  start = @webvtt.cues[0].start_in_sec
  to_remove = (start / @options[:length]).floor
  return seg.map{|s| s-to_remove}
end

#find_segments(cue) ⇒ Object 



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# File 'lib/webvtt/segmenter.rb', line 41

def find_segments(cue)
  all_cues = @webvtt.cues
  index_cue = all_cues.index(cue)
  seg = [(cue.start_in_sec / @options[:length]).floor]
  start_seg = seg[0] * @options[:length]
  end_seg = start_seg + @options[:length]

  # if the cue length is > than desired length
  # or if cue end in sec is > end of the segment in sec
  # we display it in the next segment as well

  if (cue.length > @options[:length]) ||
    (cue.end_in_sec > end_seg)

    (cue.length / @options[:length]).ceil.to_i.times.each do |s|
      seg << seg.last + 1
    end
  end

  return seg
end

#generate_playlist(files) ⇒ Object 



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# File 'lib/webvtt/segmenter.rb', line 63

def generate_playlist(files)
  lines = []
  target_duration = 0
  files.each_with_index do |file,i|

    # if first cue ever we calculate from 0 sec
    if i == 0
      total_length = file.total_length
    else
      total_length = file.actual_total_length
    end

    target_duration = total_length if total_length > target_duration
    if @options[:base_url].nil?
      url = file.filename
    else
      url = ::File.join(@options[:base_url], file.filename)
    end
    lines << %(#EXTINF:#{total_length.round},
#{url})
  end

  playlist = [%(#EXTM3U
#EXT-X-TARGETDURATION:#{target_duration.ceil}
#EXT-X-VERSION:3
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD)]
  playlist.concat(lines)
  playlist << "#EXT-X-ENDLIST"

  ::File.open(@options[:playlist], "w") {|f| f.write(playlist.join("\n")) }
  return @options[:playlist]
end

#split_to_files ⇒ Object 



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# File 'lib/webvtt/segmenter.rb', line 97

def split_to_files
  filenames = []
  segment_files = []

  @webvtt.cues.each_with_index do |cue,i|
    find_segment_files(cue).each do |seg|
      segment_files[seg] ||= []
      segment_files[seg] << cue
    end
  end

  segment_files.compact.each_with_index do |f,i|
    filename = sprintf(@options[:output], i)
    header = @webvtt.header

    if !header.include?("X-TIMESTAMP-MAP")
      # FIXME: the value should be configurable
      header << "\nX-TIMESTAMP-MAP=MPEGTS:900000,LOCAL:00:00:00.000"
    end

    content = [header, f.map{|c| c.to_webvtt }.join("\n\n")].join("\n\n")

    ::File.open(filename, "w") {|f| f.write(content)}

    filenames << filename
  end
  return filenames.map{|f| File.new(f) }
end