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 EFR_encode_frame() function, which is the primary
 * (most common, most useful) interface to our EFR encoder.
 */

#include "gsm_efr.h"

void EFR_encode_frame(struct EFR_encoder_state *st, const int16_t *pcm_in,
		      uint8_t *frame, int *sp_out, int *vad_out)
{
	int16_t params[EFR_NUM_PARAMS];
	int sp;

	EFR_encode_params(st, pcm_in, params, &sp, vad_out);
	EFR_params2frame(params, frame);
	if (!sp)
		EFR_insert_sid_codeword(frame);
	if (sp_out)
		*sp_out = sp;
}