# ----------------------------------------------------------------------------
# pyglet
# Copyright (c) 2006-2008 Alex Holkner
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# * Redistributions of source code must retain the above copyright
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# ----------------------------------------------------------------------------
'''Simple Python-only RIFF reader, supports uncompressed WAV files.
'''
__docformat__ = 'restructuredtext'
__version__ = '$Id: riff.py 2005 2008-04-13 01:03:03Z Alex.Holkner $'
# RIFF reference:
# http://www.saettler.com/RIFFMCI/riffmci.html
#
# More readable WAVE summaries:
#
# http://www.borg.com/~jglatt/tech/wave.htm
# http://www.sonicspot.com/guide/wavefiles.html
from pyglet.media import StreamingSource,AudioData,AudioFormat
from pyglet.media import MediaFormatException
import ctypes
import struct
import StringIO
WAVE_FORMAT_PCM = 0x0001
IBM_FORMAT_MULAW = 0x0101
IBM_FORMAT_ALAW = 0x0102
IBM_FORMAT_ADPCM = 0x0103
class RIFFFormatException(MediaFormatException):
pass
class WAVEFormatException(RIFFFormatException):
pass
class RIFFChunk(object):
header_fmt = '<4sL'
header_length = struct.calcsize(header_fmt)
def __init__(self, file, name, length, offset):
self.file = file
self.name = name
self.length = length
self.offset = offset
def get_data(self):
self.file.seek(self.offset)
return self.file.read(self.length)
def __repr__(self):
return '%s(%r, offset=%r, length=%r)' % (
self.__class__.__name__,
self.name,
self.offset,
self.length)
class RIFFForm(object):
_chunks = None
def __init__(self, file, offset):
self.file = file
self.offset = offset
def get_chunks(self):
if self._chunks:
return self._chunks
self._chunks = []
self.file.seek(self.offset)
offset = self.offset
while True:
header = self.file.read(RIFFChunk.header_length)
if not header:
break
name, length = struct.unpack(RIFFChunk.header_fmt, header)
offset += RIFFChunk.header_length
cls = self._chunk_types.get(name, RIFFChunk)
chunk = cls(self.file, name, length, offset)
self._chunks.append(chunk)
offset += length
if offset & 0x3 != 0:
offset = (offset | 0x3) + 1
self.file.seek(offset)
return self._chunks
def __repr__(self):
return '%s(offset=%r)' % (self.__class__.__name__, self.offset)
class RIFFType(RIFFChunk):
def __init__(self, *args, **kwargs):
super(RIFFType, self).__init__(*args, **kwargs)
self.file.seek(self.offset)
form = self.file.read(4)
if form != 'WAVE':
raise RIFFFormatException('Unsupported RIFF form "%s"' % form)
self.form = WaveForm(self.file, self.offset + 4)
class RIFFFile(RIFFForm):
_chunk_types = {
'RIFF': RIFFType,
}
def __init__(self, file):
if not hasattr(file, 'seek'):
file = StringIO.StringIO(file.read())
super(RIFFFile, self).__init__(file, 0)
def get_wave_form(self):
chunks = self.get_chunks()
if len(chunks) == 1 and isinstance(chunks[0], RIFFType):
return chunks[0].form
class WaveFormatChunk(RIFFChunk):
def __init__(self, *args, **kwargs):
super(WaveFormatChunk, self).__init__(*args, **kwargs)
fmt = '<HHLLHH'
if struct.calcsize(fmt) != self.length:
raise RIFFFormatException('Size of format chunk is incorrect.')
(self.wFormatTag,
self.wChannels,
self.dwSamplesPerSec,
self.dwAvgBytesPerSec,
self.wBlockAlign,
self.wBitsPerSample) = struct.unpack(fmt, self.get_data())
class WaveDataChunk(RIFFChunk):
pass
class WaveForm(RIFFForm):
_chunk_types = {
'fmt ': WaveFormatChunk,
'data': WaveDataChunk
}
def get_format_chunk(self):
for chunk in self.get_chunks():
if isinstance(chunk, WaveFormatChunk):
return chunk
def get_data_chunk(self):
for chunk in self.get_chunks():
if isinstance(chunk, WaveDataChunk):
return chunk
class WaveSource(StreamingSource):
def __init__(self, filename, file=None):
if file is None:
file = open(filename, 'rb')
self._file = file
# Read RIFF format, get format and data chunks
riff = RIFFFile(file)
wave_form = riff.get_wave_form()
if wave_form:
format = wave_form.get_format_chunk()
data_chunk = wave_form.get_data_chunk()
if not wave_form or not format or not data_chunk:
if not filename or filename.lower().endswith('.wav'):
raise WAVEFormatException('Not a WAVE file')
else:
raise WAVEFormatException(
'AVbin is required to decode compressed media')
if format.wFormatTag != WAVE_FORMAT_PCM:
raise WAVEFormatException('Unsupported WAVE format category')
if format.wBitsPerSample not in (8, 16):
raise WAVEFormatException('Unsupported sample bit size: %d' %
format.wBitsPerSample)
self.audio_format = AudioFormat(
channels=format.wChannels,
sample_size=format.wBitsPerSample,
sample_rate=format.dwSamplesPerSec)
self._duration = \
float(data_chunk.length) / self.audio_format.bytes_per_second
self._start_offset = data_chunk.offset
self._max_offset = data_chunk.length
self._offset = 0
self._file.seek(self._start_offset)
def _get_audio_data(self, bytes):
bytes = min(bytes, self._max_offset - self._offset)
if not bytes:
return None
data = self._file.read(bytes)
self._offset += len(data)
timestamp = float(self._offset) / self.audio_format.bytes_per_second
duration = float(bytes) / self.audio_format.bytes_per_second
return AudioData(data, len(data), timestamp, duration)
def seek(self, timestamp):
offset = int(timestamp * self.audio_format.bytes_per_second)
# Bound within duration
offset = min(max(offset, 0), self._max_offset)
# Align to sample
if self.audio_format.bytes_per_sample == 2:
offset &= 0xfffffffe
elif self.audio_format.bytes_per_sample == 4:
offset &= 0xfffffffc
self._file.seek(offset + self._start_offset)
self._offset = offset
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