--- a/.hgignore	Thu May 09 21:00:33 2024 +0000
+++ b/.hgignore	Thu May 09 23:35:25 2024 +0000
@@ -14,6 +14,7 @@
 ^amrefr/amrefr-tseq-dec$
 ^amrefr/amrefr-tseq-enc$
 
+^amrtest/twamr-decode$
 ^amrtest/twamr-encode$
 ^amrtest/twamr-tseq-dec$
 ^amrtest/twamr-tseq-enc$

--- a/amrtest/Makefile	Thu May 09 21:00:33 2024 +0000
+++ b/amrtest/Makefile	Thu May 09 23:35:25 2024 +0000
@@ -1,12 +1,15 @@
 CC=	gcc
 CFLAGS=	-O2
-PROGS=	twamr-encode twamr-tseq-dec twamr-tseq-enc
+PROGS=	twamr-decode twamr-encode twamr-tseq-dec twamr-tseq-enc
 LIBAMR=	../libtwamr/libtwamr.a
 LIBTEST=../libtest/libtest.a
 INSTBIN=/opt/freecalypso/bin
 
 all:	${PROGS}
 
+twamr-decode:	decode.o ${LIBAMR} ${LIBTEST}
+	${CC} ${CFLAGS} -o $@ $^
+
 twamr-encode:	encode.o mode_file.o mode_kw.o ${LIBAMR} ${LIBTEST}
 	${CC} ${CFLAGS} -o $@ $^
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/amrtest/decode.c	Thu May 09 23:35:25 2024 +0000
@@ -0,0 +1,71 @@
+/*
+ * twamr-decode is a speech decoder utility going from *.amr input
+ * to WAV output.  It logically replaces amrnb-dec from opencore-amr
+ * package.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include "../libtwamr/tw_amr.h"
+#include "../libtest/wavwriter.h"
+#include "../libtest/pcmwrite.h"
+
+main(argc, argv)
+	char **argv;
+{
+	FILE *inf;
+	void *wav;
+	uint8_t frm_in[AMR_IETF_MAX_PL];
+	struct amr_decoder_state *state;
+	struct amr_param_frame frame;
+	int16_t pcm[160];
+	int rc;
+
+	if (argc != 3) {
+		fprintf(stderr, "usage: %s input.amr output.wav\n", argv[0]);
+		exit(1);
+	}
+	inf = fopen(argv[1], "r");
+	if (!inf) {
+		perror(argv[1]);
+		exit(1);
+	}
+	if (fread(frm_in, 1, AMR_IETF_HDR_LEN, inf) != AMR_IETF_HDR_LEN ||
+	    bcmp(frm_in, amr_file_header_magic, AMR_IETF_HDR_LEN)) {
+		fprintf(stderr, "error: %s is not in IETF AMR format\n",
+			argv[1]);
+		exit(1);
+	}
+	wav = wav_write_open(argv[2], 8000, 16, 1);
+	if (!wav) {
+		perror(argv[2]);
+		exit(1);
+	}
+	state = amr_decoder_create();
+	if (!state) {
+		perror("amr_decoder_create()");
+		exit(1);
+	}
+	for (;;) {
+		rc = getc(inf);
+		if (rc < 0)
+			break;
+		frm_in[0] = rc;
+		rc = amr_ietf_grok_first_octet(frm_in[0]);
+		if (rc < 0) {
+inv:			fprintf(stderr, "error: %s contains invalid AMR data\n",
+				argv[1]);
+			exit(1);
+		}
+		if (rc && fread(frm_in+1, 1, rc, inf) != rc)
+			goto inv;
+		amr_frame_from_ietf(frm_in, &frame);
+		amr_decode_frame(state, &frame, pcm);
+		write_pcm_to_wav(wav, pcm);
+	}
+	wav_write_close(wav);
+	exit(0);
+}