root/Trunk/Scripts/Testing_scripts/mp3_testing/downsample.pl

#!/usr/bin/perl -w
####################################################################
###
###     script name : downsample.pl
###     version: 0.3
###             modified by: Ken MacLean
###             mail: kmaclean@voxforge.org
###             Date: 2006.9.26
###     Command: ./downsample.pl directory filetype(raw/wav) original_sampling_rate targetrate 
###
### Copyright (C) 2006 Ken MacLean
###
### This program is free software; you can redistribute it and/or
### modify it under the terms of the GNU General Public License
### as published by the Free Software Foundation; either version 3
### of the License, or (at your option) any later version.
###
### This program is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###                                                                 
####################################################################
use strict;
use File::Spec;

my ($targetrate, @command);
my ($original_file_type, @filename, $original_sampling_rate);
my ($wav_file, $raw_file);
my ($directory, $filename, $debug, $filename_nosuffix, $suffix);
 
# check usage
if (@ARGV != 4) {
  print "error -usage: $0 downsample_directory filetype(raw/wav) original_sampling_rate targetrate \n\n"; 
  exit (1);
}

# read in command line arguments
($directory, $original_sampling_rate, $targetrate, $debug) = @ARGV;

# open directory
opendir(DIR, "$directory") ||      die ("Unable to open directory: $directory");

# process each file name in directory one at a time
while ($filename = readdir(DIR)) {
  chomp ($filename);
  @filename = split(/\./,$filename);
  $filename_nosuffix = shift(@filename);
  $suffix = "@filename";
  # sox: rate: -r 8000, 16000, 44100, 48000 ...
  #      data size: -b = 8-bit; -w = 16-bit; -l = 32-bit 
  if ($suffix eq "wav") {
        print "downsampling:$directory\/$filename\n" if $debug;
    @command = ("sox", "$directory\/$filename", "-r", "$targetrate", "-w", "$directory\/temp-$filename");
    system(@command) == 0 or die "system @command failed: $?"; 
    @command = ("mv", "$directory\/temp-$filename", "$directory\/$filename");
    system(@command) == 0 or die "system @command failed: $?";      
    } 
    elsif ($suffix eq "raw") { # convert raw files to wav (i.e. add a wav header)
      print "downsampling:$directory\/$filename\n" if $debug;
      @command = ("sox", "-r", "$original_sampling_rate", "-s", "-w", "$directory\/$filename", "-t", "wav", "-r", "$targetrate", "-w", "$directory\/temp-$filename");
      system(@command) == 0 or die "system @command failed: $?"; 
      # need to leave 'raw' filename unchanged (i.e. don't rename it to wav) 
      # only change filenames using svn, otherwise lose you svn history on the file.   
      @command = ("mv", "$directory\/temp-$filename", "$directory\/$filename");
      system(@command) == 0 or die "system @command failed: $?";   
    } # skip any other files
} 
close(DIR);