diff options
Diffstat (limited to 'Lib/sndhdr.py')
| -rw-r--r-- | Lib/sndhdr.py | 107 |
1 files changed, 35 insertions, 72 deletions
diff --git a/Lib/sndhdr.py b/Lib/sndhdr.py index b7b349c..d9f8372 100644 --- a/Lib/sndhdr.py +++ b/Lib/sndhdr.py @@ -1,85 +1,45 @@ -# This module contains several routines that 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, IOError 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 whatraw() calls the "whatsound" program and interprets its -# output. You'll have to guess the sampling rate by listening though! -# -# Function what() calls whathdr() and if it doesn't recognize the file -# then calls whatraw(). -# -# 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. -# +"""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, IOError 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. -#------------------------------------------------------# -# Guess the type of any sound file, raw or with header # -#------------------------------------------------------# +#--------------------------------# +# Guess the type of a sound file # +#--------------------------------# def what(filename): res = whathdr(filename) - if not res: - res = whatraw(filename) return res -#-----------------------------# -# Guess the type of raw sound # -#-----------------------------# - -def whatraw(filename): - # Assume it's always 1 channel, byte-sized samples - # Don't assume anything about the rate - import os - from stat import ST_SIZE - # XXX "whatsound" should be part of the distribution somehow... - cmd = 'whatsound ' + filename + ' 2>/dev/null' - cmd = 'PATH=$PATH:/ufs/guido/bin/sgi\n' + cmd - pipe = os.popen(cmd, 'r') - data = pipe.read() - sts = pipe.close() - if sts: - return None - if data[:13] == '-t raw -b -s ': - type = 'sb' - sample_size = 8 - elif data[:13] == '-t raw -b -u ': - type = 'ub' - sample_size = 8 - elif data[:13] == '-t raw -b -U ': - type = 'ul' - sample_size = 'U' - else: - return None - try: - frame_count = os.stat(filename)[ST_SIZE] - except IOError: - frame_count = -1 - return type, 0, 1, frame_count, sample_size - - #-------------------------# # Recognize sound headers # #-------------------------# @@ -268,3 +228,6 @@ def testall(list, recursive, toplevel): print what(filename) except IOError: print '*** not found ***' + +if __name__ == '__main__': + test() |