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cpython/Lib/sndhdr.py /
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| """Routines to 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, OSError 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 what() calls whathdr(). (It used to also use some | |
| heuristics for raw data, but this doesn't work very well.) | |
| 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. | |
| __all__ = ['what', 'whathdr'] | |
| from collections import namedtuple | |
| SndHeaders = namedtuple('SndHeaders', | |
| 'filetype framerate nchannels nframes sampwidth') | |
| SndHeaders.filetype.__doc__ = ("""The value for type indicates the data type | |
| and will be one of the strings 'aifc', 'aiff', 'au','hcom', | |
| 'sndr', 'sndt', 'voc', 'wav', '8svx', 'sb', 'ub', or 'ul'.""") | |
| SndHeaders.framerate.__doc__ = ("""The sampling_rate will be either the actual | |
| value or 0 if unknown or difficult to decode.""") | |
| SndHeaders.nchannels.__doc__ = ("""The number of channels or 0 if it cannot be | |
| determined or if the value is difficult to decode.""") | |
| SndHeaders.nframes.__doc__ = ("""The value for frames will be either the number | |
| of frames or -1.""") | |
| SndHeaders.sampwidth.__doc__ = ("""Either the sample size in bits or | |
| 'A' for A-LAW or 'U' for u-LAW.""") | |
| def what(filename): | |
| """Guess the type of a sound file.""" | |
| res = whathdr(filename) | |
| return res | |
| def whathdr(filename): | |
| """Recognize sound headers.""" | |
| with open(filename, 'rb') as f: | |
| h = f.read(512) | |
| for tf in tests: | |
| res = tf(h, f) | |
| if res: | |
| return SndHeaders(*res) | |
| return None | |
| #-----------------------------------# | |
| # Subroutines per sound header type # | |
| #-----------------------------------# | |
| tests = [] | |
| def test_aifc(h, f): | |
| import aifc | |
| if not h.startswith(b'FORM'): | |
| return None | |
| if h[8:12] == b'AIFC': | |
| fmt = 'aifc' | |
| elif h[8:12] == b'AIFF': | |
| fmt = 'aiff' | |
| else: | |
| return None | |
| f.seek(0) | |
| try: | |
| a = aifc.open(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.startswith(b'.snd'): | |
| func = get_long_be | |
| elif h[:4] in (b'\0ds.', b'dns.'): | |
| func = get_long_le | |
| else: | |
| return None | |
| filetype = 'au' | |
| hdr_size = func(h[4:8]) | |
| data_size = func(h[8:12]) | |
| encoding = func(h[12:16]) | |
| rate = func(h[16:20]) | |
| nchannels = func(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 | |
| if frame_size: | |
| nframe = data_size / frame_size | |
| else: | |
| nframe = -1 | |
| return filetype, rate, nchannels, nframe, sample_bits | |
| tests.append(test_au) | |
| def test_hcom(h, f): | |
| if h[65:69] != b'FSSD' or h[128:132] != b'HCOM': | |
| return None | |
| divisor = get_long_be(h[144:148]) | |
| if divisor: | |
| rate = 22050 / divisor | |
| else: | |
| rate = 0 | |
| return 'hcom', rate, 1, -1, 8 | |
| tests.append(test_hcom) | |
| def test_voc(h, f): | |
| if not h.startswith(b'Creative Voice File\032'): | |
| return None | |
| sbseek = get_short_le(h[20:22]) | |
| rate = 0 | |
| if 0 <= sbseek < 500 and h[sbseek] == 1: | |
| ratecode = 256 - h[sbseek+4] | |
| if ratecode: | |
| rate = int(1000000.0 / ratecode) | |
| return 'voc', rate, 1, -1, 8 | |
| tests.append(test_voc) | |
| def test_wav(h, f): | |
| import wave | |
| # 'RIFF' <len> 'WAVE' 'fmt ' <len> | |
| if not h.startswith(b'RIFF') or h[8:12] != b'WAVE' or h[12:16] != b'fmt ': | |
| return None | |
| f.seek(0) | |
| try: | |
| w = wave.open(f, 'r') | |
| except (EOFError, wave.Error): | |
| return None | |
| return ('wav', w.getframerate(), w.getnchannels(), | |
| w.getnframes(), 8*w.getsampwidth()) | |
| tests.append(test_wav) | |
| def test_8svx(h, f): | |
| if not h.startswith(b'FORM') or h[8:12] != b'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.startswith(b'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.startswith(b'\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 bytes # | |
| #-------------------------------------------# | |
| def get_long_be(b): | |
| return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3] | |
| def get_long_le(b): | |
| return (b[3] << 24) | (b[2] << 16) | (b[1] << 8) | b[0] | |
| def get_short_be(b): | |
| return (b[0] << 8) | b[1] | |
| def get_short_le(b): | |
| return (b[1] << 8) | b[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 + '/:', end=' ') | |
| if recursive or toplevel: | |
| print('recursing down:') | |
| import glob | |
| names = glob.glob(os.path.join(glob.escape(filename), '*')) | |
| testall(names, recursive, 0) | |
| else: | |
| print('*** directory (use -r) ***') | |
| else: | |
| print(filename + ':', end=' ') | |
| sys.stdout.flush() | |
| try: | |
| print(what(filename)) | |
| except OSError: | |
| print('*** not found ***') | |
| if __name__ == '__main__': | |
| test() |