Record Wav by MediaPlayer

I've tried to use "Media Player" to record wave file; whenever record
to replace existing wave file, the file will be gone (deleted?)!! I
really do not know why!!

And, how can I change the wave file format; e.g. save as 22K, 8 bit
instead of 11K, 8 bit, or PCM U-law...

Thanks for your reply :-)