Class: M4S::Layout::Trun

Inherits:
Atom
  • Object
show all
Defined in:
lib/m4s/layout/trun.rb

Instance Attribute Summary collapse

Attributes inherited from Atom

#cache, #segment_index, #track, #track_id

Instance Method Summary collapse

Methods inherited from Atom

generate, #generate

Constructor Details

#initialize(cache, opts = {}) ⇒ Trun

Returns a new instance of Trun.



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# File 'lib/m4s/layout/trun.rb', line 7

def initialize(cache, opts = {})
  super(cache, opts)

  @data_offset = opts.fetch(:data_offset, 0)
end

Instance Attribute Details

#data_offset ⇒ Object

Returns the value of attribute data_offset.



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# File 'lib/m4s/layout/trun.rb', line 5

def data_offset
  @data_offset
end

Instance Method Details

#binary_content ⇒ Object 



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# File 'lib/m4s/layout/trun.rb', line 17

def binary_content
  flags = M4S::Binary::Trun::FLAGS

  @binary_content ||= M4S::Binary::Trun.new(
    version: 0,
    flags: flags[:data_offset] | flags[:sample_duration] | flags[:sample_size] | flags[:sample_flags] | flags[:sample_composition_time_offset],
    sample_count: entries_list.size,
    data_offset: data_offset,
    first_sample_flags: 0,
    samples: entries_list,
  ).to_binary_s
end

#encode_sample_flags(flags_hash) ⇒ Object 



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# File 'lib/m4s/layout/trun.rb', line 70

def encode_sample_flags(flags_hash)
  sample_degradation_priority = flags_hash[:sample_degradation_priority] & 0xFFFF
  sample_depends_on = flags_hash[:sample_depends_on] & 0x3
  sample_is_depended_on = flags_hash[:sample_is_depended_on] & 0x3
  sample_has_redundancy = flags_hash[:sample_has_redundancy] & 0x3
  sample_padding_value = flags_hash[:sample_padding_value] & 0x7
  sample_is_difference_sample = flags_hash[:sample_is_difference_sample] & 0x1

  flags = 0
  flags |= (sample_degradation_priority << 16)
  flags |= (sample_depends_on << 14)
  flags |= (sample_is_depended_on << 12)
  flags |= (sample_has_redundancy << 10)
  flags |= (sample_padding_value << 7)
  flags |= (sample_is_difference_sample << 6)

  flags
end

#entries_list ⇒ Object 



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# File 'lib/m4s/layout/trun.rb', line 30

def entries_list
  @entries_list ||= generate_entries_list
end

#generate_entries_list ⇒ Object 



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# File 'lib/m4s/layout/trun.rb', line 34

def generate_entries_list
  buffer = []

  cache.segment_samples(track.fetch('track_id'), segment_index).each do |sample|
    sample_flags =
      if sample.fetch('keyframe') == 'TRUE'
        {
          sample_degradation_priority: 0,
          sample_depends_on: 2, # Сэмпл не зависит от других сэмплов
          sample_is_depended_on: 0, # Другие сэмплы зависят от этого сэмпла (ключевой кадр)
          sample_has_redundancy: 0,
          sample_padding_value: 0,
          sample_is_difference_sample: 1,
        }
      else
        {
          sample_degradation_priority: 0,
          sample_depends_on: 1, # Сэмпл не зависит от других сэмплов
          sample_is_depended_on: 1, # Другие сэмплы зависят от этого сэмпла (ключевой кадр)
          sample_has_redundancy: 0,
          sample_padding_value: 0,
          sample_is_difference_sample: 0,
        }
      end

    buffer << {
      sample_duration: sample.fetch('delta'),
      sample_size: sample.fetch('size'),
      sample_flags: encode_sample_flags(sample_flags),
      sample_composition_time_offset: sample.fetch('c_delta'),
    }
  end

  buffer
end

#name ⇒ Object 



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# File 'lib/m4s/layout/trun.rb', line 13

def name
  'trun'
end