libtwamr encoder: always emit frame->mode = mode; In the original implementation of amr_encode_frame(), the 'mode' member of the output struct was set to 0xFF if the output frame type is TX_NO_DATA. This design was made to mimic the mode field (16-bit word) being set to 0xFFFF (or -1) in 3GPP test sequence format - but nothing actually depends on this struct member being set in any way, and amr_frame_to_tseq() generates the needed 0xFFFF on its own, based on frame->type being equal to TX_NO_DATA. It is simpler and more efficient to always set frame->mode to the actual encoding mode in amr_encode_frame(), and this new behavior has already been documented in doc/AMR-library-API description in anticipation of the present change.

/*
 * This header file is internal to libgsmfr2; it contains declarations
 * of internal functions for the Rx DTX preprocessor component.
 */

extern void gsmfr_preproc_gen_cn(struct gsmfr_preproc_state *state,
				 uint8_t *frame);
extern void gsmfr_preproc_sid2cn(struct gsmfr_preproc_state *state,
				 uint8_t *frame);
extern void gsmfr_preproc_invalid_sid(struct gsmfr_preproc_state *state,
				      uint8_t *frame);
extern uint16_t gsmfr_preproc_prng(struct gsmfr_preproc_state *state,
				   uint16_t no_bits);
extern uint8_t gsmfr_preproc_xmaxc_mean(const uint8_t *frame);