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module Ogg::Codecs
class Opus
class << self
include VorbisComments
# return true/false based on whether the header packet belongs to us
def match?(header_packet)
header_packet.start_with?("OpusHead")
end
#consume header and tag pages, return array of two hashes, info and tags
def decode_headers(reader)
init_pkt, tag_pkt = reader.read_packets(2) # init_pkt, tag_pkt
info = extract_info(init_pkt)
info[:tag], info[:tag_vendor] = unpack_comments(tag_pkt, "OpusTags")
info
end
# consume pages with old tags/setup packets and rewrite newtags,setup packets
# return the number of pages written
def replace_tags(reader, writer, new_tags, vendor)
_ = reader.read_packets(1) # tag_packet
writer.write_packets(0, pack_comments(new_tags, vendor, "OpusTags"))
end
def extract_info(packet)
_, # opus magic signature
_, # opus_version,
channels,
_, # pre skip
_, # samplerate,
_, # output gain
_ = packet.unpack("a8CCvVvC") # channel map
return { :channels => channels, :samplerate => 48000 }
end
end
end
end
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