Hi all, I'm working on making an AMR encoder. It is based on the source code of AMR speech codec (3GPP TS 26.073). The source wave data is encoded by this codec and then is packed into AMR storage format (draft-ietf-avt-rtp-amr-13.txt section 5). Unfortunately, the generated amr file is only the noise when playing in 7650. Can anyone give me some advice? Thanks for your attention.
There are several differences between the 3GPP and the Series 60 AMR files, most significantly that they store the frame bits in opposite order within each byte, and that the packed bits are skewed by one nibble. I have written a Python program to convert between these two formats, please see: http://www.connact.com/~eaw/amrwork for details.