Python code coverage for Lib/sndhdr.py

#	count	content
1	n/a	"""Routines to help recognizing sound files.
2	n/a
3	n/a	Function whathdr() recognizes various types of sound file headers.
4	n/a	It understands almost all headers that SOX can decode.
5	n/a
6	n/a	The return tuple contains the following items, in this order:
7	n/a	- file type (as SOX understands it)
8	n/a	- sampling rate (0 if unknown or hard to decode)
9	n/a	- number of channels (0 if unknown or hard to decode)
10	n/a	- number of frames in the file (-1 if unknown or hard to decode)
11	n/a	- number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW
12	n/a
13	n/a	If the file doesn't have a recognizable type, it returns None.
14	n/a	If the file can't be opened, OSError is raised.
15	n/a
16	n/a	To compute the total time, divide the number of frames by the
17	n/a	sampling rate (a frame contains a sample for each channel).
18	n/a
19	n/a	Function what() calls whathdr(). (It used to also use some
20	n/a	heuristics for raw data, but this doesn't work very well.)
21	n/a
22	n/a	Finally, the function test() is a simple main program that calls
23	n/a	what() for all files mentioned on the argument list. For directory
24	n/a	arguments it calls what() for all files in that directory. Default
25	n/a	argument is "." (testing all files in the current directory). The
26	n/a	option -r tells it to recurse down directories found inside
27	n/a	explicitly given directories.
28	n/a	"""
29	n/a
30	n/a	# The file structure is top-down except that the test program and its
31	n/a	# subroutine come last.
32	n/a
33	n/a	__all__ = ['what', 'whathdr']
34	n/a
35	n/a	from collections import namedtuple
36	n/a
37	n/a	SndHeaders = namedtuple('SndHeaders',
38	n/a	'filetype framerate nchannels nframes sampwidth')
39	n/a
40	n/a	SndHeaders.filetype.__doc__ = ("""The value for type indicates the data type
41	n/a	and will be one of the strings 'aifc', 'aiff', 'au','hcom',
42	n/a	'sndr', 'sndt', 'voc', 'wav', '8svx', 'sb', 'ub', or 'ul'.""")
43	n/a	SndHeaders.framerate.__doc__ = ("""The sampling_rate will be either the actual
44	n/a	value or 0 if unknown or difficult to decode.""")
45	n/a	SndHeaders.nchannels.__doc__ = ("""The number of channels or 0 if it cannot be
46	n/a	determined or if the value is difficult to decode.""")
47	n/a	SndHeaders.nframes.__doc__ = ("""The value for frames will be either the number
48	n/a	of frames or -1.""")
49	n/a	SndHeaders.sampwidth.__doc__ = ("""Either the sample size in bits or
50	n/a	'A' for A-LAW or 'U' for u-LAW.""")
51	n/a
52	n/a	def what(filename):
53	n/a	"""Guess the type of a sound file."""
54	n/a	res = whathdr(filename)
55	n/a	return res
56	n/a
57	n/a
58	n/a	def whathdr(filename):
59	n/a	"""Recognize sound headers."""
60	n/a	with open(filename, 'rb') as f:
61	n/a	h = f.read(512)
62	n/a	for tf in tests:
63	n/a	res = tf(h, f)
64	n/a	if res:
65	n/a	return SndHeaders(*res)
66	n/a	return None
67	n/a
68	n/a
69	n/a	#-----------------------------------#
70	n/a	# Subroutines per sound header type #
71	n/a	#-----------------------------------#
72	n/a
73	n/a	tests = []
74	n/a
75	n/a	def test_aifc(h, f):
76	n/a	import aifc
77	n/a	if not h.startswith(b'FORM'):
78	n/a	return None
79	n/a	if h[8:12] == b'AIFC':
80	n/a	fmt = 'aifc'
81	n/a	elif h[8:12] == b'AIFF':
82	n/a	fmt = 'aiff'
83	n/a	else:
84	n/a	return None
85	n/a	f.seek(0)
86	n/a	try:
87	n/a	a = aifc.open(f, 'r')
88	n/a	except (EOFError, aifc.Error):
89	n/a	return None
90	n/a	return (fmt, a.getframerate(), a.getnchannels(),
91	n/a	a.getnframes(), 8 * a.getsampwidth())
92	n/a
93	n/a	tests.append(test_aifc)
94	n/a
95	n/a
96	n/a	def test_au(h, f):
97	n/a	if h.startswith(b'.snd'):
98	n/a	func = get_long_be
99	n/a	elif h[:4] in (b'\0ds.', b'dns.'):
100	n/a	func = get_long_le
101	n/a	else:
102	n/a	return None
103	n/a	filetype = 'au'
104	n/a	hdr_size = func(h[4:8])
105	n/a	data_size = func(h[8:12])
106	n/a	encoding = func(h[12:16])
107	n/a	rate = func(h[16:20])
108	n/a	nchannels = func(h[20:24])
109	n/a	sample_size = 1 # default
110	n/a	if encoding == 1:
111	n/a	sample_bits = 'U'
112	n/a	elif encoding == 2:
113	n/a	sample_bits = 8
114	n/a	elif encoding == 3:
115	n/a	sample_bits = 16
116	n/a	sample_size = 2
117	n/a	else:
118	n/a	sample_bits = '?'
119	n/a	frame_size = sample_size * nchannels
120	n/a	if frame_size:
121	n/a	nframe = data_size / frame_size
122	n/a	else:
123	n/a	nframe = -1
124	n/a	return filetype, rate, nchannels, nframe, sample_bits
125	n/a
126	n/a	tests.append(test_au)
127	n/a
128	n/a
129	n/a	def test_hcom(h, f):
130	n/a	if h[65:69] != b'FSSD' or h[128:132] != b'HCOM':
131	n/a	return None
132	n/a	divisor = get_long_be(h[144:148])
133	n/a	if divisor:
134	n/a	rate = 22050 / divisor
135	n/a	else:
136	n/a	rate = 0
137	n/a	return 'hcom', rate, 1, -1, 8
138	n/a
139	n/a	tests.append(test_hcom)
140	n/a
141	n/a
142	n/a	def test_voc(h, f):
143	n/a	if not h.startswith(b'Creative Voice File\032'):
144	n/a	return None
145	n/a	sbseek = get_short_le(h[20:22])
146	n/a	rate = 0
147	n/a	if 0 <= sbseek < 500 and h[sbseek] == 1:
148	n/a	ratecode = 256 - h[sbseek+4]
149	n/a	if ratecode:
150	n/a	rate = int(1000000.0 / ratecode)
151	n/a	return 'voc', rate, 1, -1, 8
152	n/a
153	n/a	tests.append(test_voc)
154	n/a
155	n/a
156	n/a	def test_wav(h, f):
157	n/a	import wave
158	n/a	# 'RIFF' <len> 'WAVE' 'fmt ' <len>
159	n/a	if not h.startswith(b'RIFF') or h[8:12] != b'WAVE' or h[12:16] != b'fmt ':
160	n/a	return None
161	n/a	f.seek(0)
162	n/a	try:
163	n/a	w = wave.openfp(f, 'r')
164	n/a	except (EOFError, wave.Error):
165	n/a	return None
166	n/a	return ('wav', w.getframerate(), w.getnchannels(),
167	n/a	w.getnframes(), 8*w.getsampwidth())
168	n/a
169	n/a	tests.append(test_wav)
170	n/a
171	n/a
172	n/a	def test_8svx(h, f):
173	n/a	if not h.startswith(b'FORM') or h[8:12] != b'8SVX':
174	n/a	return None
175	n/a	# Should decode it to get #channels -- assume always 1
176	n/a	return '8svx', 0, 1, 0, 8
177	n/a
178	n/a	tests.append(test_8svx)
179	n/a
180	n/a
181	n/a	def test_sndt(h, f):
182	n/a	if h.startswith(b'SOUND'):
183	n/a	nsamples = get_long_le(h[8:12])
184	n/a	rate = get_short_le(h[20:22])
185	n/a	return 'sndt', rate, 1, nsamples, 8
186	n/a
187	n/a	tests.append(test_sndt)
188	n/a
189	n/a
190	n/a	def test_sndr(h, f):
191	n/a	if h.startswith(b'\0\0'):
192	n/a	rate = get_short_le(h[2:4])
193	n/a	if 4000 <= rate <= 25000:
194	n/a	return 'sndr', rate, 1, -1, 8
195	n/a
196	n/a	tests.append(test_sndr)
197	n/a
198	n/a
199	n/a	#-------------------------------------------#
200	n/a	# Subroutines to extract numbers from bytes #
201	n/a	#-------------------------------------------#
202	n/a
203	n/a	def get_long_be(b):
204	n/a	return (b[0] << 24) \| (b[1] << 16) \| (b[2] << 8) \| b[3]
205	n/a
206	n/a	def get_long_le(b):
207	n/a	return (b[3] << 24) \| (b[2] << 16) \| (b[1] << 8) \| b[0]
208	n/a
209	n/a	def get_short_be(b):
210	n/a	return (b[0] << 8) \| b[1]
211	n/a
212	n/a	def get_short_le(b):
213	n/a	return (b[1] << 8) \| b[0]
214	n/a
215	n/a
216	n/a	#--------------------#
217	n/a	# Small test program #
218	n/a	#--------------------#
219	n/a
220	n/a	def test():
221	n/a	import sys
222	n/a	recursive = 0
223	n/a	if sys.argv[1:] and sys.argv[1] == '-r':
224	n/a	del sys.argv[1:2]
225	n/a	recursive = 1
226	n/a	try:
227	n/a	if sys.argv[1:]:
228	n/a	testall(sys.argv[1:], recursive, 1)
229	n/a	else:
230	n/a	testall(['.'], recursive, 1)
231	n/a	except KeyboardInterrupt:
232	n/a	sys.stderr.write('\n[Interrupted]\n')
233	n/a	sys.exit(1)
234	n/a
235	n/a	def testall(list, recursive, toplevel):
236	n/a	import sys
237	n/a	import os
238	n/a	for filename in list:
239	n/a	if os.path.isdir(filename):
240	n/a	print(filename + '/:', end=' ')
241	n/a	if recursive or toplevel:
242	n/a	print('recursing down:')
243	n/a	import glob
244	n/a	names = glob.glob(os.path.join(filename, '*'))
245	n/a	testall(names, recursive, 0)
246	n/a	else:
247	n/a	print('* directory (use -r) *')
248	n/a	else:
249	n/a	print(filename + ':', end=' ')
250	n/a	sys.stdout.flush()
251	n/a	try:
252	n/a	print(what(filename))
253	n/a	except OSError:
254	n/a	print('* not found *')
255	n/a
256	n/a	if __name__ == '__main__':
257	n/a	test()