We are talking about mp3 audio, not wave or m4a or flac or aif or ...!!!
if you convert this flv file to a mp3 file with the same values, in fact it's like you have extracted audio file with out any changes!! before converting it, notice at this values to set in output file:
Bit rate mode : Constant (CBR)
Bit rate : 128 Kbps
Channel(s) : 2 channels
Sampling rate : 44.1 KHz
then convert it!!
