wav_reader.py

import struct
import sys

class NamedStruct( struct.Struct ):
    def __init__(self, *contents):
        """
        Construct with ("Format", "Name"), tuples as arguments.
        """
        self.names, format = zip(*contents)
        #Flatten format into a string
        format = "".join( format )
        
        struct.Struct.__init__( self, format )
    
    def unpack( self, str ):
        return dict( zip( self.names, struct.Struct.unpack( self, str ) ) )
    
wav_file_header = NamedStruct( ("4c", id), # should always contain "RIFF"
                               ("i",  totallength), # total file length minus 8
                               ("8c", wavefmt), # should be "WAVEfmt "
                               ("i", format), # 16 for PCM format
                               ("h", cm), # 1 for PCM format
                               ("h", channels), # channels
                               ("i", requency), # sampling frequency
                               ("i", bytes_per_second),
                               ("h", bytes_by_capture),
                               ("h", bits_per_sample),
                               ("4c", data[4]), # should always contain "data"
                               ("i", bytes_in_data) )

filename = sys.argv[1]
try:
    wav = open( filename, "rb" )
except IOError:
    print  "Can't open input file %s" % filename
    sys.exit(-1)

try:
    header = wav_file_header.unpack( wav.read( wav_file_header.size ) )
except IOError:
    print "Can't read file header"
    sys.exit(-1)

if header["id"] != "RIFF":
    print "ERROR: Not wav format"
    sys.exit(-1)

sum = 0
value_unpacker = struct.Struct("h")
while True:
    try:
        value = value_unpacker.unpack( wav.read(value_unpacker.size) )
    except IOError:
        break
        
    sum += abs( value )

print sum

Assume correct endianness to match C code, otherwise lob a couple of < or > into the struct definitions.