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 defines the interface to our reader function for binary
 * files recording GSM FR or EFR streams, see ../doc/Binary-file-format.
 *
 * binfile_read_frame() return values are:
 *  1 = successfully read valid frame
 *  0 = normal EOF
 * -1 = unrecognized header byte
 * -2 = EOF in the middle of a frame
 */

#define	BINFILE_MAX_FRAME	33

extern int binfile_read_frame(FILE *binf, uint8_t *frame);