How to capture raw audio data with amr codec?

HI,guys.
i want to write something like skype for symbian device,so i need to capture raw audio data with amr encoder. after trying QMediaRecord and QAudioInput,unluckily,i can not get what i want.

i could capture 'raw' data by QAudioInput class,but looks like it only supported audio/pcm. i could record audio with amr format,but i can not get 'raw' data in time.i mean by QMediaRecorder, must save audio to file at first.

what can i do? thanks for any suggestion~