Method: MP4Info#initialize

Defined in:
lib/mp4info.rb

#initialize(io_stream) ⇒ MP4Info

Initialize a new MP4Info object from an IO object



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# File 'lib/mp4info.rb', line 29

def initialize(io_stream)
  # Tag atoms
  @data_atoms = {
    "AART" => nil, "ALB" => nil, "ART" => nil, "CMT" => nil,
    "COVR" => nil, "CPIL" => nil, "CPRT" => nil, "DAY" => nil,
    "DISK" => nil, "GEN" => nil, "GNRE" => nil, "GRP" => nil,
    "NAM" => nil, "RTNG" => nil, "TMPO" => nil, "TOO" => nil,
    "TRKN" => nil, "WRT" => nil, "APID" => nil, "AKID" => nil,
    "ATID" => nil, "CNID" => nil, "GEID" => nil, "PLID" => nil,
    "TITL" => nil, "DSCP" => nil, "PERF" => nil, "AUTH" => nil
  }
  
  # Info atoms
  @info_atoms = {
    "VERSION" => nil, "BITRATE" => nil, "FREQUENCY" => nil, "MS" => nil,
    "SIZE" => nil, "SECS" => nil, "MM" => nil, "SS" => nil, "ENCRYPTED" => nil,
    "TIME" => nil, "COPYRIGHT" => nil, "LAYER" => nil
  }

  # Atoms that contain other atoms
  @container_atoms = {
    "ILST" => nil, "MDIA" => nil, "MINF" => nil, "MOOV" => nil,
    "STBL" => nil, "TRAK" => nil, "UDTA" => nil
  }
  
  # Non standard data atoms
  @other_atoms = {
    "MDAT" => :parse_mdat, "META" => :parse_meta,
    "MVHD" => :parse_mvhd, "STSD" => :parse_stsd,
    "MOOV" => :parse_moov, "UUID" => :parse_uuid
  }
  
  # Info/Tag aliases
  @aliases = {}
  
  # Just in case
  io_stream.binmode
  
  # Sanity check
  head = read_or_raise(io_stream, 8, "#{io_stream} does not appear to be an IO stream")
  raise "#{io_stream} does not appear to be an MP4 file" unless head[4..7].downcase == "ftyp"
  
  # Back to the beginning
  io_stream.rewind
  
  parse_container io_stream, 0, io_stream.stat.size
  
  @info_atoms["VERSION"] = 4
  @info_atoms["LAYER"] = 1 if @info_atoms["FREQUENCY"]
  if (@info_atoms["SIZE"] && @info_atoms["MS"])
    @info_atoms["BITRATE"] = ( 0.5 + @info_atoms["SIZE"] /
      ( ( @info_atoms["MM"] * 60 + @info_atoms["SS"] + (@info_atoms["MS"] * 1.0) / 1000 ) * 128 ) ).floor
  end
  @info_atoms["COPYRIGHT"] = true if @info_atoms["CPRT"]
end