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.

/*
 * The vad_reset() function implemented in this module is new with libtwamr,
 * i.e., it does not originate from 3GPP, even though it is styled after
 * 3GPP AMR code.  This function initializes our unified vadState structure,
 * which is a union of vadState1 and vadState2, plus a selection flag.
 */

#include "typedef.h"
#include "namespace.h"
#include "vad.h"

void vad_reset(vadState *st, Flag use_vad2)
{
	st->use_vad2 = use_vad2;
	if (st->use_vad2)
		vad2_reset(&st->u.v2);
	else
		vad1_reset(&st->u.v1);
}