--- a/.hgignore	Sun Nov 20 18:08:41 2022 +0000
+++ b/.hgignore	Sun Nov 20 23:04:27 2022 +0000
@@ -5,10 +5,10 @@
 ^dev/gsm0611-silence-fr$
 ^dev/gsm0611-silence-fr\.out$
 
-^frtest/cn-debug$
 ^frtest/gsmfr-cvt-dlcap$
 ^frtest/gsmfr-decode$
 ^frtest/gsmfr-encode$
+^frtest/gsmfr-max-out$
 ^frtest/gsmfr-preproc$
 
 ^miscutil/gsmrec-dump$

--- a/frtest/Makefile	Sun Nov 20 18:08:41 2022 +0000
+++ b/frtest/Makefile	Sun Nov 20 23:04:27 2022 +0000
@@ -1,7 +1,6 @@
 CC=	gcc
 CFLAGS=	-O2
-PROGS=	gsmfr-cvt-dlcap gsmfr-decode gsmfr-encode gsmfr-preproc
-NOINST=	cn-debug
+PROGS=	gsmfr-cvt-dlcap gsmfr-decode gsmfr-encode gsmfr-max-out gsmfr-preproc
 LIBPP=	../libgsmfrp/libgsmfrp.a
 LIBTEST=../libtest/libtest.a
 LIBDEC=	${LIBTEST} ${LIBPP}
@@ -9,10 +8,7 @@
 
 CVT_OBJS=cvt-dlcap.o tidsp.o
 
-all:	${PROGS} ${NOINST}
-
-cn-debug:	cn-debug.o ${LIBDEC}
-	${CC} ${CFLAGS} -o $@ cn-debug.o ${LIBDEC} -lgsm
+all:	${PROGS}
 
 gsmfr-cvt-dlcap:	${CVT_OBJS}
 	${CC} ${CFLAGS} -o $@ ${CVT_OBJS}
@@ -23,6 +19,9 @@
 gsmfr-encode:	encode.o ${LIBTEST}
 	${CC} ${CFLAGS} -o $@ encode.o ${LIBTEST} -lgsm
 
+gsmfr-max-out:	max-out.o ${LIBDEC}
+	${CC} ${CFLAGS} -o $@ max-out.o ${LIBDEC} -lgsm
+
 gsmfr-preproc:	preproc.o ${LIBDEC}
 	${CC} ${CFLAGS} -o $@ preproc.o ${LIBDEC}
 
@@ -31,4 +30,4 @@
 	install -c ${PROGS} ${INSTBIN}
 
 clean:
-	rm -f *.o *.out ${PROGS} ${NOINST}
+	rm -f *.o *.out ${PROGS}

--- a/frtest/cn-debug.c	Sun Nov 20 18:08:41 2022 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,99 +0,0 @@
-/*
- * This program has been written as part of the debug investigation,
- * seeking to understand how and why our FR comfort noise generator
- * is currently broken.
- */
-
-#include <stdio.h>
-#include <stdint.h>
-#include <stdlib.h>
-#include <gsm.h>
-#include "../libgsmfrp/gsm_fr_preproc.h"
-#include "../libtest/binreader.h"
-
-main(argc, argv)
-	char **argv;
-{
-	FILE *binf;
-	gsm dec_state;
-	struct gsmfr_preproc_state *pp_state;
-	unsigned frame_index;
-	uint8_t frame[BINFILE_MAX_FRAME];
-	int16_t pcm[160];
-	gsm_signal fr_params[76];
-	int rc, bfi, taf;
-	int i, j, n;
-	unsigned samp_abs, samp_max;
-
-	if (argc != 2) {
-		fprintf(stderr, "usage: %s bin-stream-file\n", argv[0]);
-		exit(1);
-	}
-	binf = fopen(argv[1], "r");
-	if (!binf) {
-		perror(argv[1]);
-		exit(1);
-	}
-	dec_state = gsm_create();
-	if (!dec_state) {
-		fprintf(stderr, "gsm_create() failed!\n");
-		exit(1);
-	}
-	pp_state = gsmfr_preproc_create();
-	if (!pp_state) {
-		fprintf(stderr, "gsmfr_preproc_create() failed!\n");
-		exit(1);
-	}
-	for (frame_index = 0; ; frame_index++) {
-		rc = binfile_read_frame(binf, frame);
-		if (rc < 0) {
-			fprintf(stderr, "error: garbage in %s\n", argv[1]);
-			exit(1);
-		}
-		if (!rc)
-			break;
-		printf("#%u: ", frame_index);
-		switch (frame[0] & 0xF0) {
-		case 0xB0:
-			bfi = 1;
-			taf = frame[1] & 1;
-			printf("BFI TAF=%u\n", taf);
-			break;
-		case 0xC0:
-			fprintf(stderr, "error: %s is not in FR codec format\n",
-				argv[1]);
-			exit(1);
-		case 0xD0:
-			bfi = 0;
-			fputs("FR", stdout);
-			gsm_explode(dec_state, frame, fr_params);
-			n = 0;
-			for (i = 0; i < 8; i++)
-				printf(" %u", fr_params[n++]);
-			putchar('\n');
-			for (i = 0; i < 4; i++) {
-				putchar(' ');
-				for (j = 0; j < 17; j++)
-					printf(" %u", fr_params[n++]);
-				putchar('\n');
-			}
-			break;
-		}
-		if (bfi)
-			gsmfr_preproc_bfi(pp_state, taf, frame);
-		else
-			gsmfr_preproc_good_frame(pp_state, frame);
-		gsm_decode(dec_state, frame, pcm);
-		samp_max = 0;
-		for (i = 0; i < 160; i++) {
-			if (pcm[i] >= 0)
-				samp_abs = pcm[i];
-			else
-				samp_abs = -pcm[i];
-			if (samp_abs > samp_max)
-				samp_max = samp_abs;
-		}
-		printf("  MAX=%u\n", samp_max);
-	}
-	exit(0);
-}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/frtest/max-out.c	Sun Nov 20 23:04:27 2022 +0000
@@ -0,0 +1,102 @@
+/*
+ * This program reads an extended-libgsm binary file, dumps every frame in
+ * human-readable form just like gsmrec-dump, but then also passes it through
+ * our GSM FR decoder (libgsmfrp+libgsm) and looks for the highest-magnitude
+ * PCM sample in the decoder output.  This maximum output sample magnitude is
+ * reported after the dump of each input frame.  This program is intended to
+ * serve as a debug aid, for troubleshooting of our libgsmfrp+libgsm stack.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <gsm.h>
+#include "../libgsmfrp/gsm_fr_preproc.h"
+#include "../libtest/binreader.h"
+
+main(argc, argv)
+	char **argv;
+{
+	FILE *binf;
+	gsm dec_state;
+	struct gsmfr_preproc_state *pp_state;
+	unsigned frame_index;
+	uint8_t frame[BINFILE_MAX_FRAME];
+	int16_t pcm[160];
+	gsm_signal fr_params[76];
+	int rc, bfi, taf;
+	int i, j, n;
+	unsigned samp_abs, samp_max;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s bin-stream-file\n", argv[0]);
+		exit(1);
+	}
+	binf = fopen(argv[1], "r");
+	if (!binf) {
+		perror(argv[1]);
+		exit(1);
+	}
+	dec_state = gsm_create();
+	if (!dec_state) {
+		fprintf(stderr, "gsm_create() failed!\n");
+		exit(1);
+	}
+	pp_state = gsmfr_preproc_create();
+	if (!pp_state) {
+		fprintf(stderr, "gsmfr_preproc_create() failed!\n");
+		exit(1);
+	}
+	for (frame_index = 0; ; frame_index++) {
+		rc = binfile_read_frame(binf, frame);
+		if (rc < 0) {
+			fprintf(stderr, "error: garbage in %s\n", argv[1]);
+			exit(1);
+		}
+		if (!rc)
+			break;
+		printf("#%u: ", frame_index);
+		switch (frame[0] & 0xF0) {
+		case 0xB0:
+			bfi = 1;
+			taf = frame[1] & 1;
+			printf("BFI TAF=%u\n", taf);
+			break;
+		case 0xD0:
+			bfi = 0;
+			fputs("FR", stdout);
+			gsm_explode(dec_state, frame, fr_params);
+			n = 0;
+			for (i = 0; i < 8; i++)
+				printf(" %u", fr_params[n++]);
+			putchar('\n');
+			for (i = 0; i < 4; i++) {
+				putchar(' ');
+				for (j = 0; j < 17; j++)
+					printf(" %u", fr_params[n++]);
+				putchar('\n');
+			}
+			break;
+		default:
+			fprintf(stderr, "error: %s is not in FR codec format\n",
+				argv[1]);
+			exit(1);
+		}
+		if (bfi)
+			gsmfr_preproc_bfi(pp_state, taf, frame);
+		else
+			gsmfr_preproc_good_frame(pp_state, frame);
+		gsm_decode(dec_state, frame, pcm);
+		samp_max = 0;
+		for (i = 0; i < 160; i++) {
+			if (pcm[i] >= 0)
+				samp_abs = pcm[i];
+			else
+				samp_abs = -pcm[i];
+			if (samp_abs > samp_max)
+				samp_max = samp_abs;
+		}
+		printf("  MAX=%u\n", samp_max);
+	}
+	exit(0);
+}