Lib/sunaudio.py

   1 """Interpret sun audio headers."""
   2
   3 MAGIC = '.snd'
   4
   5 class error(Exception):
   6     pass
   7
   8
   9 def get_long_be(s):
  10     """Convert a 4-char value to integer."""
  11     return (ord(s[0])<<24) | (ord(s[1])<<16) | (ord(s[2])<<8) | ord(s[3])
  12
  13
  14 def gethdr(fp):
  15     """Read a sound header from an open file."""
  16     if fp.read(4) != MAGIC:
  17         raise error, 'gethdr: bad magic word'
  18     hdr_size = get_long_be(fp.read(4))
  19     data_size = get_long_be(fp.read(4))
  20     encoding = get_long_be(fp.read(4))
  21     sample_rate = get_long_be(fp.read(4))
  22     channels = get_long_be(fp.read(4))
  23     excess = hdr_size - 24
  24     if excess < 0:
  25         raise error, 'gethdr: bad hdr_size'
  26     if excess > 0:
  27         info = fp.read(excess)
  28     else:
  29         info = ''
  30     return (data_size, encoding, sample_rate, channels, info)
  31
  32
  33 def printhdr(file):
  34     """Read and print the sound header of a named file."""
  35     hdr = gethdr(open(file, 'r'))
  36     data_size, encoding, sample_rate, channels, info = hdr
  37     while info[-1:] == '\0':
  38         info = info[:-1]
  39     print 'File name:  ', file
  40     print 'Data size:  ', data_size
  41     print 'Encoding:   ', encoding
  42     print 'Sample rate:', sample_rate
  43     print 'Channels:   ', channels
  44     print 'Info:       ', repr(info)