E1: change dummy fill frame generation method

In the absence of a proper TFO transform (TS 28.062 section
C3.2.1.1), OsmoMGW-E1 inserts constant fill frames when there is
no RTP input, or when RTP input fails conversion to TRAU-DL and
thus does not enqueue anything to the I.460 mux.  (We accept
TW-TS-001 and TW-TS-002 from RTP side, but bad frames cannot be
converted to TRAU-DL without a TFO transform.)

Prior to the present change, this idle fill of the DL was done
using fully hard-coded frames, i.e., the operation of converting
the desired fill to TRAU-DL bit format was done once externally
and the raw bit frames were hard-coded.  Change this approach:
use fill frames in RTP format provided by libosmocodec, and
execute osmo_rtp2trau() followed by osmo_trau_frame_encode() in
the fill frame output path just like we do for regular RTP to DL.

Depends: libosmocore.git I2c510ac62a0786c137115c45eee7a48b9736265f
Change-Id: I123f77295c56d61ff9aac5f5d64b25eca01e0d63

Author: Mychaela N. Falconia

TODO-RELEASE

@@ -9,3 +9,4 @@
 #library	what			description / commit summary line
 libosmocore		bump_dep; workaround	Bump libosmocore version dependency after I68328adb952ca8833ba047cb3b49ccc6f8a1f1b5
 						has been merged to libosmocore.git; then remove my_msgb_copy_c wrapper function.
+libosmocodec		bump_dep		We depend on the additions of I2c510ac62a0786c137115c45eee7a48b9736265f

configure.ac

@@ -45,6 +45,7 @@ AC_SUBST(LIBRARY_DLSYM)
 
 
 PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.11.0)
+PKG_CHECK_MODULES(LIBOSMOCODEC, libosmocodec >= 1.11.0)
 PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm >= 1.11.0)
 PKG_CHECK_MODULES(LIBOSMOCTRL, libosmoctrl >= 1.11.0)
 PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 1.11.0)

src/libosmo-mgcp/Makefile.am

@@ -7,6 +7,7 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	-Wall \
 	$(LIBOSMOCORE_CFLAGS) \
+	$(LIBOSMOCODEC_CFLAGS) \
 	$(LIBOSMOGSM_CFLAGS) \
 	$(LIBOSMOVTY_CFLAGS) \
 	$(LIBOSMONETIF_CFLAGS) \

src/libosmo-mgcp/mgcp_e1.c

@@ -57,149 +57,6 @@ static const struct e1inp_line_ops dummy_e1_line_ops = {
 	.sign_link = NULL,
 };
 
-/* The following EFR TRAU-DL frame is a dummy to be transmitted in the absence
- * of RTP-derived TRAU-DL frames.  The payload bit content here is the decoder
- * homing frame (DHF) of TS 46.060 section 8.2 Table 7 - the best we can do
- * in the absence of a proper TFO transform for EFR - while the full TRAU-DL
- * frame was generated by passing said EFR DHF through osmo_rtp2trau().
- */
-static const ubit_t idle_tf_efr[] = {
-	0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 1, 1, 0, 1, 0, 0, 0,
-	0, 0, 0, 0, 1, 1, 1, 1,
-	1, 1, 0, 0, 0, 0, 1, 0,
-	0, 0, 0, 1, 0, 1, 1, 1,
-	1, 1, 0, 1, 0, 1, 1, 0,
-	1, 0, 0, 1, 0, 0, 1, 0,
-	1, 0, 0, 0, 1, 1, 1, 1,
-	1, 0, 0, 1, 0, 1, 0, 1,
-	1, 0, 1, 0, 1, 1, 0, 1,
-	0, 1, 1, 0, 0, 0, 0, 0,
-	1, 0, 0, 1, 1, 1, 1, 1,
-	0, 0, 0, 1, 1, 1, 0, 1,
-	1, 0, 0, 0, 0, 1, 1, 0,
-	0, 0, 0, 1, 1, 0, 0, 0,
-	1, 0, 0, 0, 1, 1, 1, 1,
-	0, 1, 1, 0, 1, 1, 0, 0,
-	1, 0, 0, 1, 1, 0, 0, 0,
-	1, 0, 0, 0, 0, 1, 0, 1,
-	1, 1, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 1, 0, 0, 1, 0, 0,
-	0, 0, 0, 0, 0, 0, 1, 0,
-	1, 0, 1, 0, 1, 0, 1, 0,
-	1, 1, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 1, 1, 1, 0,
-	1, 1, 1, 0, 1, 0, 1, 1,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-};
-
-/* The following FRv1 TRAU-DL frame is a dummy to be transmitted in the absence
- * of RTP-derived TRAU-DL frames.  The payload bit content here is the silence
- * frame of TS 46.011 Table 1 - the best we can do without integrating the
- * TFO transform for FRv1 from Themyscira libgsmfr2 - while the full TRAU-DL
- * frame was generated by passing said FRv1 silence frame through
- * osmo_rtp2trau().
- */
-static const ubit_t idle_tf_fr[] = {
-	0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 1, 1, 1, 0, 0, 0, 0,
-	0, 0, 0, 0, 1, 1, 1, 1,
-	1, 0, 1, 0, 1, 0, 1, 1,
-	1, 1, 0, 0, 1, 1, 0, 1,
-	1, 0, 1, 0, 1, 0, 1, 0,
-	1, 0, 0, 1, 0, 0, 1, 0,
-	1, 1, 1, 0, 0, 1, 0, 0,
-	0, 0, 1, 0, 1, 0, 0, 0,
-	1, 1, 0, 0, 0, 0, 0, 0,
-	0, 1, 1, 0, 0, 0, 1, 1,
-	1, 1, 0, 0, 0, 1, 0, 0,
-	1, 1, 1, 0, 1, 1, 0, 1,
-	1, 1, 0, 1, 1, 0, 0, 0,
-	1, 0, 0, 1, 1, 1, 0, 1,
-	1, 1, 0, 0, 0, 0, 1, 0,
-	1, 0, 0, 0, 1, 0, 0, 0,
-	1, 0, 0, 0, 0, 1, 1, 0,
-	0, 0, 1, 1, 1, 0, 0, 0,
-	1, 1, 0, 0, 1, 1, 1, 0,
-	1, 1, 0, 1, 1, 0, 1, 1,
-	1, 0, 0, 0, 1, 0, 0, 1,
-	1, 1, 0, 1, 1, 0, 0, 0,
-	1, 0, 1, 0, 1, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0,
-	1, 1, 1, 0, 0, 0, 1, 1,
-	1, 0, 0, 0, 1, 0, 0, 1,
-	1, 1, 1, 0, 1, 1, 0, 1,
-	1, 0, 1, 1, 0, 0, 0, 1,
-	1, 0, 0, 1, 1, 1, 0, 1,
-	1, 0, 0, 0, 0, 1, 0, 1,
-	1, 0, 0, 0, 1, 0, 0, 0,
-	0, 0, 0, 0, 1, 1, 0, 0,
-	1, 0, 1, 1, 1, 0, 0, 0,
-	1, 0, 0, 1, 1, 1, 0, 1,
-	1, 1, 0, 1, 1, 0, 1, 1,
-	0, 0, 0, 1, 0, 0, 1, 1,
-	1, 1, 0, 1, 1, 0, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-};
-
-/* Idle speech frame, see also GSM 08.60, chapter 3.4 */
-static const ubit_t idle_tf_spch[] = {
-	0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 1, 1, 1, 0, 0, 0,
-	0, 0, 0, 0, 1, 0, 0, 0,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 0,
-	1, 1, 1, 1, 1, 1, 1, 1,
-};
-
 /* If the RTP transmission has dropouts for some reason the I.460 TX-Queue may
  * run empty. In order to make sure that the TRAU frame transmission continues
  * we generate idle TRAU frames here. */
@@ -208,33 +65,54 @@ static void e1_i460_mux_empty_cb(struct osmo_i460_subchan *schan, void *user_dat
 	struct mgcp_endpoint *endp = user_data;
 	struct rate_ctr_group *rate_ctrs = endp->trunk->ratectr.e1_stats;
 	struct msgb *msg = msgb_alloc_c(endp->trunk, E1_TRAU_BITS_MSGB, "E1-I.460-IDLE-TX-TRAU-frame");
-	uint8_t *ptr;
-	const uint8_t *ptr_ft;
-	enum osmo_trau_frame_type ft;
+	const uint8_t *dummy_fill_pl;
+	unsigned dummy_fill_pl_len;
+	struct osmo_trau_frame tf;
+	int rc;
 
 	rate_ctr_inc(rate_ctr_group_get_ctr(rate_ctrs, E1_I460_TRAU_MUX_EMPTY_CTR));
 
-	/* Choose an appropiate idle frame type */
-	ft = endp->e1.trau_rtp_st->type;
-	switch (ft) {
+	/* choose dummy fill frame payload based on current codec */
+	switch (endp->e1.trau_rtp_st->type) {
 	case OSMO_TRAU16_FT_FR:
-		ptr_ft = idle_tf_fr;
+		dummy_fill_pl = osmo_gsm611_silence_frame;
+		dummy_fill_pl_len = GSM_FR_BYTES;
 		break;
 	case OSMO_TRAU16_FT_EFR:
-		ptr_ft = idle_tf_efr;
+		dummy_fill_pl = osmo_gsm660_homing_frame;
+		dummy_fill_pl_len = GSM_EFR_BYTES;
 		break;
 	default:
-		/* FIXME: What about 8k subslots and AMR frames? */
-		ptr_ft = idle_tf_spch;
+		LOGPENDP(endp, DE1, LOGL_ERROR, "E1-I.460-IDLE-TX: unsupported frame type\n");
+		goto skip;
 	}
 
-	/* Put the replacement into a message buffer and enqueue it into the
-	 * I.460 multiplexer */
-	ptr = msgb_put(msg, E1_TRAU_BITS);
-	memcpy(ptr, ptr_ft, E1_TRAU_BITS);
+	/* turn it into a TRAU-DL frame */
+	memset(&tf, 0, sizeof(tf));
+	tf.dir = OSMO_TRAU_DIR_DL;
+	rc = osmo_rtp2trau(&tf, dummy_fill_pl, dummy_fill_pl_len, endp->e1.trau_rtp_st);
+	if (rc < 0) {
+		LOGPENDP(endp, DE1, LOGL_ERROR,
+			 "E1-I.460-IDLE-TX: error converting dummy fill frame!\n");
+		goto skip;
+	}
+	rc = osmo_trau_frame_encode(msgb_data(msg), msg->data_len, &tf);
+	if (rc < 0) {
+		LOGPENDP(endp, DE1, LOGL_ERROR,
+			 "E1-I.460-IDLE-TX: error encoding dummy fill frame!\n");
+		goto skip;
+	}
+	msgb_put(msg, rc);
+
+	/* enqueue it into the I.460 multiplexer */
 	LOGPENDP(endp, DE1, LOGL_DEBUG, "E1-I.460-IDLE-TX: enquing %u trau frame bits: %s...\n", msgb_length(msg),
 		 osmo_ubit_dump(msgb_data(msg), msgb_length(msg) > DEBUG_BITS_MAX ? DEBUG_BITS_MAX : msgb_length(msg)));
 	osmo_i460_mux_enqueue(endp->e1.schan, msg);
+	return;
+
+skip:
+	rate_ctr_inc(rate_ctr_group_get_ctr(rate_ctrs, E1_I460_TRAU_TX_FAIL_CTR));
+	msgb_free(msg);
 }
 
 /* called by I.460 de-multiplexer; feed output of I.460 demux into TRAU frame sync */

src/osmo-mgw/Makefile.am

@@ -27,6 +27,7 @@ osmo_mgw_SOURCES = \
 osmo_mgw_LDADD = \
 	$(top_builddir)/src/libosmo-mgcp/libosmo-mgcp.a \
 	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOCODEC_LIBS) \
 	$(LIBOSMOVTY_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
 	$(LIBOSMOCTRL_LIBS) \

tests/mgcp/Makefile.am

@@ -36,6 +36,7 @@ mgcp_test_SOURCES = \
 mgcp_test_LDADD = \
 	$(top_builddir)/src/libosmo-mgcp/libosmo-mgcp.a \
 	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOCODEC_LIBS) \
 	$(LIBOSMOVTY_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
 	$(LIBOSMOABIS_LIBS) \