"""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() |