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)