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Kaydet (Commit) 3601e88c authored tarafından Guido van Rossum's avatar Guido van Rossum
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Sjoerd Mullender writes: 

"""
Extended chunk so that it can also handle formats that are almost
according to EA IFF 85.  In particular, added options to handle
little-endian and to handle formats that include the header size in
the chunk size value.

Fixed a bug where the header size was included in the chunk size, which
it isn't according to EA IFF 85.

Added a new method getsize() to get the size of the chunk (excluding
header).

Fixed chunk documentation (TIFF doesn't look like it uses chunks).
Converted wave to use chunk.  Wave uses EA IFF 85 chunks except that
it uses little-endian encoding of integer data.

Removed __del__ methods from aifc and wave since I got an
AttributeError there upon exit.
"""
üst 2900ff93
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Showing with 50 additions and 147 deletions
Lib/aifc.py
Dosyayı görüntüle @ 3601e88c
......@@ -293,8 +293,6 @@ class Aifc_read:
self._comm_chunk_read = 0
while 1:
self._ssnd_seek_needed = 1
#DEBUG: SGI's soundfiler has a bug. There should
# be no need to check for EOF here.
try:
chunk = Chunk(self._file)
except EOFError:
......@@ -337,10 +335,6 @@ class Aifc_read:
# else, assume it is an open file object already
self.initfp(f)
def __del__(self):
if self._file:
self.close()
#
# User visible methods.
#
......
Lib/chunk.py
Dosyayı görüntüle @ 3601e88c
......@@ -49,19 +49,24 @@ default is 1, i.e. aligned.
"""
class Chunk:
def __init__(self, file, align = 1):
def __init__(self, file, align = 1, bigendian = 1, inclheader = 0):
import struct
self.closed = 0
self.align = align # whether to align to word (2-byte) boundaries
if bigendian:
strflag = '>'
else:
strflag = '<'
self.file = file
self.chunkname = file.read(4)
if len(self.chunkname) < 4:
raise EOFError
try:
self.chunksize = struct.unpack('>l', file.read(4))[0]
self.chunksize = struct.unpack(strflag+'l', file.read(4))[0]
except struct.error:
raise EOFError
self.chunksize = self.chunksize - 8 # subtract header
if inclheader:
self.chunksize = self.chunksize - 8 # subtract header
self.size_read = 0
try:
self.offset = self.file.tell()
......@@ -74,6 +79,10 @@ class Chunk:
"""Return the name (ID) of the current chunk."""
return self.chunkname
def getsize(self):
"""Return the size of the current chunk."""
return self.chunksize
def close(self):
if not self.closed:
self.skip()
......
Lib/wave.py
Dosyayı görüntüle @ 3601e88c
......@@ -85,87 +85,7 @@ if struct.pack("h", 1) == "\000\001":
else:
big_endian = 0
def _read_long(file):
x = 0L
for i in range(4):
byte = file.read(1)
if byte == '':
raise EOFError
x = x + (ord(byte) << (8 * i))
if x >= 0x80000000L:
x = x - 0x100000000L
return int(x)
def _read_ulong(file):
x = 0L
for i in range(4):
byte = file.read(1)
if byte == '':
raise EOFError
x = x + (ord(byte) << (8 * i))
return x
def _read_short(file):
x = 0
for i in range(2):
byte = file.read(1)
if byte == '':
raise EOFError
x = x + (ord(byte) << (8 * i))
if x >= 0x8000:
x = x - 0x10000
return x
def _write_short(f, x):
d, m = divmod(x, 256)
f.write(chr(m))
f.write(chr(d))
def _write_long(f, x):
if x < 0:
x = x + 0x100000000L
for i in range(4):
d, m = divmod(x, 256)
f.write(chr(int(m)))
x = d
class Chunk:
def __init__(self, file):
self.file = file
self.chunkname = self.file.read(4)
if len(self.chunkname) < 4:
raise EOFError
self.chunksize = _read_long(self.file)
self.size_read = 0
self.offset = self.file.tell()
def rewind(self):
self.file.seek(self.offset, 0)
self.size_read = 0
def setpos(self, pos):
if pos < 0 or pos > self.chunksize:
raise RuntimeError
self.file.seek(self.offset + pos, 0)
self.size_read = pos
def read(self, length):
if self.size_read >= self.chunksize:
return ''
if length > self.chunksize - self.size_read:
length = self.chunksize - self.size_read
data = self.file.read(length)
self.size_read = self.size_read + len(data)
return data
def skip(self):
try:
self.file.seek(self.chunksize - self.size_read, 1)
except RuntimeError:
while self.size_read < self.chunksize:
dummy = self.read(8192)
if not dummy:
raise EOFError
from chunk import Chunk
class Wave_read:
# Variables used in this class:
......@@ -197,41 +117,34 @@ class Wave_read:
# _data_chunk -- instantiation of a chunk class for the DATA chunk
# _framesize -- size of one frame in the file
## access _file, _nchannels, _nframes, _sampwidth, _framerate, \
## _comptype, _compname, _soundpos, \
## _fmt_chunk_read, _data_seek_needed, \
## _data_chunk, _framesize: private
def initfp(self, file):
self._file = file
self._convert = None
self._soundpos = 0
form = self._file.read(4)
if form != 'RIFF':
self._file = Chunk(file, bigendian = 0)
if self._file.getname() != 'RIFF':
raise Error, 'file does not start with RIFF id'
formlength = _read_long(self._file)
if formlength <= 0:
raise Error, 'invalid FORM chunk data size'
formdata = self._file.read(4)
formlength = formlength - 4
if formdata != 'WAVE':
if self._file.read(4) != 'WAVE':
raise Error, 'not a WAVE file'
self._fmt_chunk_read = 0
while formlength > 0:
self._data_chunk = None
while 1:
self._data_seek_needed = 1
chunk = Chunk(self._file)
if chunk.chunkname == 'fmt ':
try:
chunk = Chunk(self._file, bigendian = 0)
except EOFError:
break
chunkname = chunk.getname()
if chunkname == 'fmt ':
self._read_fmt_chunk(chunk)
self._fmt_chunk_read = 1
elif chunk.chunkname == 'data':
elif chunkname == 'data':
if not self._fmt_chunk_read:
raise Error, 'data chunk before fmt chunk'
self._data_chunk = chunk
self._nframes = chunk.chunksize / self._framesize
self._data_seek_needed = 0
formlength = formlength - 8 - chunk.chunksize
if formlength > 0:
chunk.skip()
break
chunk.skip()
if not self._fmt_chunk_read or not self._data_chunk:
raise Error, 'fmt chunk and/or data chunk missing'
......@@ -241,10 +154,6 @@ class Wave_read:
# else, assume it is an open file object already
self.initfp(f)
def __del__(self):
if self._file:
self.close()
#
# User visible methods.
#
......@@ -298,10 +207,10 @@ class Wave_read:
def readframes(self, nframes):
if self._data_seek_needed:
self._data_chunk.rewind()
self._data_chunk.seek(0, 0)
pos = self._soundpos * self._framesize
if pos:
self._data_chunk.setpos(pos)
self._data_chunk.seek(pos, 0)
self._data_seek_needed = 0
if nframes == 0:
return ''
......@@ -310,12 +219,17 @@ class Wave_read:
# something that only looks like a file object, so
# we have to reach into the innards of the chunk object
import array
chunk = self._data_chunk
data = array.array(_array_fmts[self._sampwidth])
nitems = nframes * self._nchannels
if nitems * self._sampwidth > self._data_chunk.chunksize - self._data_chunk.size_read:
nitems = (self._data_chunk.chunksize - self._data_chunk.size_read) / self._sampwidth
data.fromfile(self._data_chunk.file, nitems)
self._data_chunk.size_read = self._data_chunk.size_read + nitems * self._sampwidth
if nitems * self._sampwidth > chunk.chunksize - chunk.size_read:
nitems = (chunk.chunksize - chunk.size_read) / self._sampwidth
data.fromfile(chunk.file.file, nitems)
# "tell" data chunk how much was read
chunk.size_read = chunk.size_read + nitems * self._sampwidth
# do the same for the outermost chunk
chunk = chunk.file
chunk.size_read = chunk.size_read + nitems * self._sampwidth
data.byteswap()
data = data.tostring()
else:
......@@ -328,16 +242,12 @@ class Wave_read:
#
# Internal methods.
#
## access *: private
def _read_fmt_chunk(self, chunk):
wFormatTag = _read_short(chunk)
self._nchannels = _read_short(chunk)
self._framerate = _read_long(chunk)
dwAvgBytesPerSec = _read_long(chunk)
wBlockAlign = _read_short(chunk)
wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<hhllh', chunk.read(14))
if wFormatTag == WAVE_FORMAT_PCM:
self._sampwidth = (_read_short(chunk) + 7) / 8
sampwidth = struct.unpack('<h', chunk.read(2))[0]
self._sampwidth = (sampwidth + 7) / 8
else:
raise Error, 'unknown format: ' + `wFormatTag`
self._framesize = self._nchannels * self._sampwidth
......@@ -369,10 +279,6 @@ class Wave_write:
# _nframeswritten -- the number of frames actually written
# _datawritten -- the size of the audio samples actually written
## access _file, _comptype, _compname, _nchannels, _sampwidth, \
## _framerate, _nframes, _nframeswritten, \
## _datalength, _datawritten: private
def __init__(self, f):
if type(f) == type(''):
f = __builtin__.open(f, 'wb')
......@@ -512,7 +418,6 @@ class Wave_write:
#
# Internal methods.
#
## access *: private
def _ensure_header_written(self, datasize):
if not self._datawritten:
......@@ -530,28 +435,23 @@ class Wave_write:
self._nframes = initlength / (self._nchannels * self._sampwidth)
self._datalength = self._nframes * self._nchannels * self._sampwidth
self._form_length_pos = self._file.tell()
_write_long(self._file, 36 + self._datalength)
self._file.write('WAVE')
self._file.write('fmt ')
_write_long(self._file, 16)
_write_short(self._file, WAVE_FORMAT_PCM)
_write_short(self._file, self._nchannels)
_write_long(self._file, self._framerate)
_write_long(self._file, self._nchannels * self._framerate * self._sampwidth)
_write_short(self._file, self._nchannels * self._sampwidth)
_write_short(self._file, self._sampwidth * 8)
self._file.write('data')
self._file.write(struct.pack('<lsslhhllhhs',
36 + self._datalength, 'WAVE', 'fmt ', 16,
WAVE_FORMAT_PCM, self._nchannels, self._framerate,
self._nchannels * self._framerate * self._sampwidth,
self._nchannels * self._sampwidth,
self._sampwidth * 8, 'data'))
self._data_length_pos = self._file.tell()
_write_long(self._file, self._datalength)
self._file.write(struct.pack('<l', self._datalength))
def _patchheader(self):
if self._datawritten == self._datalength:
return
curpos = self._file.tell()
self._file.seek(self._form_length_pos, 0)
_write_long(self._file, 36 + self._datawritten)
self._file.write(struct.pack('<l', 36 + self._datawritten))
self._file.seek(self._data_length_pos, 0)
_write_long(self._file, self._datawritten)
self._file.write(struct.pack('<l', self._datawritten))
self._file.seek(curpos, 0)
self._datalength = self._datawritten
......
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