Be aware that there is a bug in the audio capture functionality of the 7610 MMAPI implementation. The 7610 is a series 60 DP2 handset and is specified to support audio capture and the amr codec in its MMAPI implementation.
On my test device the player will not start when trying to capture audio using amr. It works fine when using wav encoding though.
Looking at "audio.encodings", audio/amr is stated as supported. If getSupportedContentTypes() is called for "capture" it also lists amr support.
I find this very annoying. The variations in MMAPI functionality from handset to handset are difficult enough to deal with. The devices can at least be expected to comply with their specifications.
My firmware version is V4.0437.4, 15-09-04, RH-51.