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module WaveFile
module ChunkReaders
# Internal
class FormatChunkReader < BaseChunkReader # :nodoc:
def initialize(io, chunk_size)
@io = io
@chunk_size = chunk_size
end
def read
if @chunk_size < MINIMUM_CHUNK_SIZE
raise_error InvalidFormatError, "The format chunk is incomplete; it contains fewer than the required number of fields."
end
raw_bytes = read_entire_chunk_body(CHUNK_IDS[:format])
format_chunk = {}
format_chunk[:audio_format],
format_chunk[:channels],
format_chunk[:sample_rate],
format_chunk[:byte_rate],
format_chunk[:block_align],
format_chunk[:bits_per_sample] = raw_bytes.slice!(0...MINIMUM_CHUNK_SIZE).unpack("vvVVvv")
if format_chunk[:audio_format] == FORMAT_CODES[:extensible] || (format_chunk[:audio_format] != FORMAT_CODES[:pcm] && @chunk_size > MINIMUM_CHUNK_SIZE)
if raw_bytes.length < 2
raise_error InvalidFormatError, "The format chunk is missing an expected extension."
end
format_chunk[:extension_size] = raw_bytes.slice!(0...2).unpack(UNSIGNED_INT_16).first
if format_chunk[:extension_size] > raw_bytes.length
raise_error InvalidFormatError, "The format chunk extension size of #{format_chunk[:extension_size]} bytes is too large to fit in the format chunk. The format chunk has a stated size of #{@chunk_size} bytes, with #{raw_bytes.length} bytes available for the extension."
end
if format_chunk[:audio_format] == FORMAT_CODES[:extensible]
if format_chunk[:extension_size] < 22
raise_error InvalidFormatError, "The format chunk extension size of #{format_chunk[:extension_size]} bytes is too small. Since the format chunk has a format code of #{FORMAT_CODES[:extensible]} (i.e. WAVE_FORMAT_EXTENSIBLE), the extension size must be at least 22 bytes."
end
format_chunk[:valid_bits_per_sample] = raw_bytes.slice!(0...2).unpack(UNSIGNED_INT_16).first
format_chunk[:speaker_mapping] = raw_bytes.slice!(0...4).unpack(UNSIGNED_INT_32).first
format_chunk[:sub_audio_format_guid] = raw_bytes.slice!(0...16)
end
end
UnvalidatedFormat.new(format_chunk)
end
private
MINIMUM_CHUNK_SIZE = 16
end
end
end
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