Converting large mp3 to wav files - error: Unknown length

[Andrechang]

I am having issue with loading a large wav file.
So what I did was: I loaded a mp3 file with more than 20min music and then saved it as wav.
But when I load the wav that I just generated it gives the error below:

/home/achang/torch/install/share/lua/5.1/audio/init.lua:56: [read_audio] Unknown length at /tmp/luarocks_audio-0.1-0-130/lua---audio/generic/sox.c:45
stack traceback:
    [C]: in function 'load'
    /home/achang/torch/install/share/lua/5.1/audio/init.lua:56: in function 'load'
    mp3_play.lua:16: in function 'load_file'
    [string "x = load_file('music.wav')"]:1: in main chunk
    [C]: in function 'xpcall'
    /home/achang/torch/install/share/lua/5.1/trepl/init.lua:670: in function 'repl'
    ...hang/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:199: in main chunk
    [C]: at 0x00405d50

I use the code below to convert:

function convert_mp3_2_wav(file_path)                                            
   local x, sample_rate = audio.load(file_path)                                  
   local outpath = file_path:gsub(".mp3", ".wav")                                                                               
   audio.save(outpath, x, sample_rate)                                           
end

When use a player the wav file sounds fine.