cpython/Lib/sndhdr.py
1994-01-14 16:46:14 +00:00

271 lines
6.4 KiB
Python

# This module contains several routines that 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 whatraw() calls the "whatsound" program and interprets its
# output. You'll have to guess the sampling rate by listening though!
#
# Function what() calls whathdr() and if it doesn't recognize the file
# then calls whatraw().
#
# 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.
#------------------------------------------------------#
# Guess the type of any sound file, raw or with header #
#------------------------------------------------------#
def what(filename):
res = whathdr(filename)
if not res:
res = whatraw(filename)
return res
#-----------------------------#
# Guess the type of raw sound #
#-----------------------------#
def whatraw(filename):
# Assume it's always 1 channel, byte-sized samples
# Don't assume anything about the rate
import os
from stat import ST_SIZE
# XXX "whatsound" should be part of the distribution somehow...
cmd = 'whatsound ' + filename + ' 2>/dev/null'
cmd = 'PATH=$PATH:/ufs/guido/bin/sgi\n' + cmd
pipe = os.popen(cmd, 'r')
data = pipe.read()
sts = pipe.close()
if sts:
return None
if data[:13] == '-t raw -b -s ':
type = 'sb'
sample_size = 8
elif data[:13] == '-t raw -b -u ':
type = 'ub'
sample_size = 8
elif data[:13] == '-t raw -b -U ':
type = 'ul'
sample_size = 'U'
else:
return None
try:
frame_count = os.stat(filename)[ST_SIZE]
except IOError:
frame_count = -1
return type, 0, 1, frame_count, sample_size
#-------------------------#
# Recognize sound headers #
#-------------------------#
def whathdr(filename):
f = open(filename, 'r')
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 ***'