/usr/lib/python2.7/sndhdr.py is in libpython2.7-stdlib 2.7.11-7ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 | """Routines to help recognizing sound files.
Function whathdr() recognizes various types of sound file headers.
It understands almost all headers that SOX can decode.
The return tuple contains the following items, in this order:
- file type (as SOX understands it)
- sampling rate (0 if unknown or hard to decode)
- number of channels (0 if unknown or hard to decode)
- number of frames in the file (-1 if unknown or hard to decode)
- number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW
If the file doesn't have a recognizable type, it returns None.
If the file can't be opened, IOError is raised.
To compute the total time, divide the number of frames by the
sampling rate (a frame contains a sample for each channel).
Function what() calls whathdr(). (It used to also use some
heuristics for raw data, but this doesn't work very well.)
Finally, the function test() is a simple main program that calls
what() for all files mentioned on the argument list. For directory
arguments it calls what() for all files in that directory. Default
argument is "." (testing all files in the current directory). The
option -r tells it to recurse down directories found inside
explicitly given directories.
"""
# The file structure is top-down except that the test program and its
# subroutine come last.
__all__ = ["what","whathdr"]
def what(filename):
"""Guess the type of a sound file"""
res = whathdr(filename)
return res
def whathdr(filename):
"""Recognize sound headers"""
f = open(filename, 'rb')
h = f.read(512)
for tf in tests:
res = tf(h, f)
if res:
return res
return None
#-----------------------------------#
# Subroutines per sound header type #
#-----------------------------------#
tests = []
def test_aifc(h, f):
import aifc
if h[:4] != 'FORM':
return None
if h[8:12] == 'AIFC':
fmt = 'aifc'
elif h[8:12] == 'AIFF':
fmt = 'aiff'
else:
return None
f.seek(0)
try:
a = aifc.openfp(f, 'r')
except (EOFError, aifc.Error):
return None
return (fmt, a.getframerate(), a.getnchannels(), \
a.getnframes(), 8*a.getsampwidth())
tests.append(test_aifc)
def test_au(h, f):
if h[:4] == '.snd':
f = get_long_be
elif h[:4] in ('\0ds.', 'dns.'):
f = get_long_le
else:
return None
type = 'au'
hdr_size = f(h[4:8])
data_size = f(h[8:12])
encoding = f(h[12:16])
rate = f(h[16:20])
nchannels = f(h[20:24])
sample_size = 1 # default
if encoding == 1:
sample_bits = 'U'
elif encoding == 2:
sample_bits = 8
elif encoding == 3:
sample_bits = 16
sample_size = 2
else:
sample_bits = '?'
frame_size = sample_size * nchannels
return type, rate, nchannels, data_size//frame_size, sample_bits
tests.append(test_au)
def test_hcom(h, f):
if h[65:69] != 'FSSD' or h[128:132] != 'HCOM':
return None
divisor = get_long_be(h[128+16:128+20])
return 'hcom', 22050//divisor, 1, -1, 8
tests.append(test_hcom)
def test_voc(h, f):
if h[:20] != 'Creative Voice File\032':
return None
sbseek = get_short_le(h[20:22])
rate = 0
if 0 <= sbseek < 500 and h[sbseek] == '\1':
ratecode = ord(h[sbseek+4])
rate = int(1000000.0 / (256 - ratecode))
return 'voc', rate, 1, -1, 8
tests.append(test_voc)
def test_wav(h, f):
# 'RIFF' <len> 'WAVE' 'fmt ' <len>
if h[:4] != 'RIFF' or h[8:12] != 'WAVE' or h[12:16] != 'fmt ':
return None
style = get_short_le(h[20:22])
nchannels = get_short_le(h[22:24])
rate = get_long_le(h[24:28])
sample_bits = get_short_le(h[34:36])
return 'wav', rate, nchannels, -1, sample_bits
tests.append(test_wav)
def test_8svx(h, f):
if h[:4] != 'FORM' or h[8:12] != '8SVX':
return None
# Should decode it to get #channels -- assume always 1
return '8svx', 0, 1, 0, 8
tests.append(test_8svx)
def test_sndt(h, f):
if h[:5] == 'SOUND':
nsamples = get_long_le(h[8:12])
rate = get_short_le(h[20:22])
return 'sndt', rate, 1, nsamples, 8
tests.append(test_sndt)
def test_sndr(h, f):
if h[:2] == '\0\0':
rate = get_short_le(h[2:4])
if 4000 <= rate <= 25000:
return 'sndr', rate, 1, -1, 8
tests.append(test_sndr)
#---------------------------------------------#
# Subroutines to extract numbers from strings #
#---------------------------------------------#
def get_long_be(s):
return (ord(s[0])<<24) | (ord(s[1])<<16) | (ord(s[2])<<8) | ord(s[3])
def get_long_le(s):
return (ord(s[3])<<24) | (ord(s[2])<<16) | (ord(s[1])<<8) | ord(s[0])
def get_short_be(s):
return (ord(s[0])<<8) | ord(s[1])
def get_short_le(s):
return (ord(s[1])<<8) | ord(s[0])
#--------------------#
# Small test program #
#--------------------#
def test():
import sys
recursive = 0
if sys.argv[1:] and sys.argv[1] == '-r':
del sys.argv[1:2]
recursive = 1
try:
if sys.argv[1:]:
testall(sys.argv[1:], recursive, 1)
else:
testall(['.'], recursive, 1)
except KeyboardInterrupt:
sys.stderr.write('\n[Interrupted]\n')
sys.exit(1)
def testall(list, recursive, toplevel):
import sys
import os
for filename in list:
if os.path.isdir(filename):
print filename + '/:',
if recursive or toplevel:
print 'recursing down:'
import glob
names = glob.glob(os.path.join(filename, '*'))
testall(names, recursive, 0)
else:
print '*** directory (use -r) ***'
else:
print filename + ':',
sys.stdout.flush()
try:
print what(filename)
except IOError:
print '*** not found ***'
if __name__ == '__main__':
test()
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