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 module contains our gsmfr_0610_encode_frame() function, which is
 * the primary (most common, most useful) interface to our GSM 06.10 encoder.
 */

#include <stdint.h>
#include "tw_gsmfr.h"

void gsmfr_0610_encode_frame(struct gsmfr_0610_state *st, const int16_t *pcm,
			     uint8_t *frame)
{
	struct gsmfr_param_frame param;

	gsmfr_0610_encode_params(st, pcm, &param);
	gsmfr_pack_frame(&param, frame);
}