def wave_header_footer(self):
"""returns (header, footer) tuple of strings
containing all data before and after the PCM stream
may raise ValueError if there's a problem with
the header or footer data
may raise IOError if there's a problem reading
header or footer data from the file"""
from audiotools import decoders
decoder = decoders.SHNDecoder(open(self.filename, "rb"))
(head, tail) = decoder.pcm_split()
decoder.close()
if ((head[0:4] == b"RIFF") and (head[8:12] == b"WAVE")):
return (head, tail)
else:
raise ValueError("invalid wave header")
def has_foreign_aiff_chunks(self):
"""returns True if the audio file contains non-audio AIFF chunks
during transcoding, if the source audio file has foreign AIFF chunks
and the target audio format supports foreign AIFF chunks,
conversion should be routed through .aiff conversion
to avoid losing those chunks"""
from audiotools import decoders
from audiotools import bitstream
from io import BytesIO
try:
(head, tail) = decoders.SHNDecoder(open(self.filename,
"rb")).pcm_split()
header = bitstream.BitstreamReader(BytesIO(head), 0)
(FORM, SIZE, AIFF) = header.parse("4b 32u 4b")
if ((FORM != 'FORM') or (AIFF != 'AIFF')):
return False
# if the tail has room for chunks, there must be some foreign ones
if (len(tail) >= 8):
return True
# otherwise, check the header for foreign chunks
total_size = len(head) - bitstream.format_byte_size("4b 32u 4b")
while (total_size >= 8):
(chunk_id, chunk_size) = header.parse("4b 32u")
total_size -= bitstream.format_byte_size("4b 32u")
if (chunk_id not in ('COMM', 'SSND')):
return True
else:
if (chunk_size % 2):
header.skip_bytes(chunk_size + 1)
total_size -= chunk_size + 1
else:
header.skip_bytes(chunk_size)
total_size -= chunk_size
else:
# no foreign chunks found
return False
except IOError:
return False
def aiff_header_footer(self):
"""returns (header, footer) tuple of strings
containing all data before and after the PCM stream
if self.has_foreign_aiff_chunks() is False,
may raise ValueError if the file has no header and footer
for any reason"""
from audiotools import decoders
from audiotools import bitstream
from io import BytesIO
decoder = decoders.SHNDecoder(open(self.filename, "rb"))
(head, tail) = decoder.pcm_split()
decoder.close()
if ((head[0:4] == b"FORM") and (head[8:12] == b"AIFF")):
return (head, tail)
else:
raise ValueError("invalid AIFF header")
def aiff_header_footer(self):
"""returns (header, footer) tuple of strings
containing all data before and after the PCM stream
if self.has_foreign_aiff_chunks() is False,
may raise ValueError if the file has no header and footer
for any reason"""
from audiotools import decoders
from audiotools import bitstream
from io import BytesIO
(head, tail) = decoders.SHNDecoder(open(self.filename,
"rb")).pcm_split()
header = bitstream.BitstreamReader(BytesIO(head), 0)
(FORM, SIZE, AIFF) = header.parse("4b 32u 4b")
if ((FORM != 'FORM') or (AIFF != 'AIFF')):
raise ValueError("invalid AIFF header")
else:
return (head, tail)
def wave_header_footer(self):
"""returns (header, footer) tuple of strings
containing all data before and after the PCM stream
may raise ValueError if there's a problem with
the header or footer data
may raise IOError if there's a problem reading
header or footer data from the file"""
from audiotools import decoders
from audiotools import bitstream
from io import BytesIO
(head, tail) = decoders.SHNDecoder(open(self.filename,
"rb")).pcm_split()
header = bitstream.BitstreamReader(BytesIO(head), 1)
(RIFF, SIZE, WAVE) = header.parse("4b 32u 4b")
if ((RIFF != 'RIFF') or (WAVE != 'WAVE')):
raise ValueError("invalid wave header")
else:
return (head, tail)
