downsample sound files using ffmpeg

lower_samplerate_cmds.py

def is_wav(p):
    
    return os.path.splitext(p)[-1] == '.wav'

def lower_samplerate_cmds(dir_src, samplerate, dir_dst, fpath_exec_script):
    
    paths = fs.gen_paths(dir_src, is_wav)
    commands = []
    for fpath in paths:
        path_dst = os.path.join(dir_dst, os.path.basename(fpath))
        cmd = ['ffmpeg', '-i', fpath, '-ac', '2', '-ar', "%d" % (samplerate,), path_dst]
        commands.append(cmd)
        
    commands = [list2cmdline(cmd) for cmd in commands]
         
    with open(fpath_exec_script, 'w') as f:
        for cmd in commands:
            f.write('%s\n' % (cmd,))