WavHeader.py

# WavHeader.py
#   Extract basic header information from a WAV file
# python WavHeader.py start.wav
 
def PrintWavHeader(strWAVFile):
    """ Extracts data in the first 44 bytes in a WAV file and writes it
            out in a human-readable format
    """
    import os
    import struct
    import logging
    logging.basicConfig(level=logging.DEBUG)
    def DumpHeaderOutput(structHeaderFields):
        for key in structHeaderFields.keys():
            print "%s: " % (key), structHeaderFields[key]
        # end for
    # Open file
    try:
        fileIn = open(strWAVFile, 'rb')
    except IOError, err:
        logging.debug("Could not open input file %s" % (strWAVFile))
        return
    # end try
    # Read in all data
    bufHeader = fileIn.read(38)
    # Verify that the correct identifiers are present
    if (bufHeader[0:4] != "RIFF") or \
       (bufHeader[12:16] != "fmt "): 
         logging.debug("Input file not a standard WAV file")
         return
    # endif
    stHeaderFields = {'ChunkSize' : 0, 'Format' : '',
        'Subchunk1Size' : 0, 'AudioFormat' : 0,
        'NumChannels' : 0, 'SampleRate' : 0,
        'ByteRate' : 0, 'BlockAlign' : 0,
        'BitsPerSample' : 0, 'Filename': ''}
    # Parse fields
    stHeaderFields['ChunkSize'] = struct.unpack('<L', bufHeader[4:8])[0]
    stHeaderFields['Format'] = bufHeader[8:12]
    stHeaderFields['Subchunk1Size'] = struct.unpack('<L', bufHeader[16:20])[0]
    stHeaderFields['AudioFormat'] = struct.unpack('<H', bufHeader[20:22])[0]
    stHeaderFields['NumChannels'] = struct.unpack('<H', bufHeader[22:24])[0]
    stHeaderFields['SampleRate'] = struct.unpack('<L', bufHeader[24:28])[0]
    stHeaderFields['ByteRate'] = struct.unpack('<L', bufHeader[28:32])[0]
    stHeaderFields['BlockAlign'] = struct.unpack('<H', bufHeader[32:34])[0]
    stHeaderFields['BitsPerSample'] = struct.unpack('<H', bufHeader[34:36])[0]
    # Locate & read data chunk
    chunksList = []
    dataChunkLocation = 0
    fileIn.seek(0, 2) # Seek to end of file
    inputFileSize = fileIn.tell()
    nextChunkLocation = 12 # skip the RIFF header
    while 1:
        # Read subchunk header
        fileIn.seek(nextChunkLocation)
        bufHeader = fileIn.read(8)
        if bufHeader[0:4] == "data":
            dataChunkLocation = nextChunkLocation
        # endif
        nextChunkLocation += (8 + struct.unpack('<L', bufHeader[4:8])[0])
        chunksList.append(bufHeader[0:4])
        if nextChunkLocation >= inputFileSize:
            break
        # endif
    # end while
    # Dump subchunk list
    print "Subchunks Found: "
    for chunkName in chunksList:
        print "%s, " % (chunkName),
    # end for
    print "\n"
    # Dump data chunk information
    if dataChunkLocation != 0:
        fileIn.seek(dataChunkLocation)
        bufHeader = fileIn.read(8)
        print "Data Chunk located at offset [%s] of data length [%s] bytes" % \
            (dataChunkLocation, struct.unpack('<L', bufHeader[4:8])[0])
    # endif
    # Print output
    stHeaderFields['Filename'] = os.path.basename(strWAVFile)
    DumpHeaderOutput(stHeaderFields)
    # Close file
    fileIn.close()
 
if __name__ == "__main__":
    import sys
    if len(sys.argv) != 2:
        print "Invalid argument. Exactly one wave file location required as argument"
    else:
        PrintWavHeader(sys.argv[1])