Make RTP payload type configurable

For a long time the RTP payload type was hard-coded for outgoing
frames. The problem is that according to RFC 3551 only GSM FR has
a static payload type value (see table 4, value 3). For other
codecs the payload type may be negotiated between the both
sides dynamically (i.e. in range 96-127).

Let's allow a binary/API user to configure this manually.

Change-Id: Ia07ed4e13b4a70c8bb4181564a8190861fd269da
Closes: OS#2482

4 files changed, 64 insertions, 18 deletions

diff --git a/include/osmocom/gapk/procqueue.h b/include/osmocom/gapk/procqueue.h
index ac9253b..82c1cf9 100644
--- a/include/osmocom/gapk/procqueue.h
+++ b/include/osmocom/gapk/procqueue.h
@@ -89,8 +89,10 @@ int osmo_gapk_pq_queue_file_input(struct osmo_gapk_pq *pq, FILE *src, unsigned i
 int osmo_gapk_pq_queue_file_output(struct osmo_gapk_pq *pq, FILE *dst, unsigned int block_len);
 
 /* RTP */
-int osmo_gapk_pq_queue_rtp_input(struct osmo_gapk_pq *pq, int rtp_fd, unsigned int block_len);
-int osmo_gapk_pq_queue_rtp_output(struct osmo_gapk_pq *pq, int rtp_fd, unsigned int block_len);
+int osmo_gapk_pq_queue_rtp_input(struct osmo_gapk_pq *pq, int rtp_fd,
+	unsigned int block_len, uint8_t pt);
+int osmo_gapk_pq_queue_rtp_output(struct osmo_gapk_pq *pq, int rtp_fd,
+	unsigned int block_len, uint8_t pt);
 
 /* ALSA */
 int osmo_gapk_pq_queue_alsa_input(struct osmo_gapk_pq *pq, const char *hwdev, unsigned int blk_len);
diff --git a/src/app_osmo_gapk.c b/src/app_osmo_gapk.c
index a4b93ef..91647ee 100644
--- a/src/app_osmo_gapk.c
+++ b/src/app_osmo_gapk.c
@@ -64,6 +64,9 @@ struct gapk_options
 	const char *alsa_out;
 	const struct osmo_gapk_format_desc *fmt_out;
 
+	/* RTP payload type */
+	uint8_t rtp_pt_in, rtp_pt_out;
+
 	int benchmark;
 	int verbose;
 };
@@ -133,6 +136,8 @@ print_help(char *progname)
 #endif
 	fprintf(stdout, "  -f, --input-format=FMT\tInput format (see below)\n");
 	fprintf(stdout, "  -g, --output-format=FMT\tOutput format (see below)\n");
+	fprintf(stdout, "  -p  --rtp-pt-in=TYPE\t\tRTP payload type for incoming frames\n");
+	fprintf(stdout, "  -P  --rtp-pt-out=TYPE\t\tRTP payload type for outgoing frames\n");
 	fprintf(stdout, "  -b, --enable-benchmark\tEnable codec benchmarking\n");
 	fprintf(stdout, "  -v, --verbose\t\t\tEnable debug messages\n");
 	fprintf(stdout, "\n");
@@ -203,11 +208,13 @@ parse_options(struct gapk_state *state, int argc, char *argv[])
 #endif
 		{"input-format", 1, 0, 'f'},
 		{"output-format", 1, 0, 'g'},
+		{"rtp-pt-in", 1, 0, 'p'},
+		{"rtp-pt-out", 1, 0, 'P'},
 		{"enable-benchmark", 0, 0, 'b'},
 		{"verbose", 0, 0, 'v'},
 		{"help", 0, 0, 'h'},
 	};
-	const char *short_options = "i:o:I:O:f:g:bvh"
+	const char *short_options = "i:o:I:O:f:g:p:P:bvh"
 #ifdef HAVE_ALSA
 		"a:A:"
 #endif
@@ -218,6 +225,10 @@ parse_options(struct gapk_state *state, int argc, char *argv[])
 	/* Set some defaults */
 	memset(opt, 0x00, sizeof(*opt));
 
+	/* Default RTP payload type (GSM FR, see RFC 3551) */
+	opt->rtp_pt_in = 3;
+	opt->rtp_pt_out = 3;
+
 	/* Parse */
 	while (1) {
 		int c, rv;
@@ -279,6 +290,24 @@ parse_options(struct gapk_state *state, int argc, char *argv[])
 			}
 			break;
 
+		case 'p':
+			rv = atoi(optarg);
+			if (rv < 0 || rv > 0xff) {
+				LOGP(DAPP, LOGL_ERROR, "Invalid RTP payload type: %d\n", rv);
+				return -EINVAL;
+			}
+			opt->rtp_pt_in = rv;
+			break;
+
+		case 'P':
+			rv = atoi(optarg);
+			if (rv < 0 || rv > 0xff) {
+				LOGP(DAPP, LOGL_ERROR, "Invalid RTP payload type: %d\n", rv);
+				return -EINVAL;
+			}
+			opt->rtp_pt_out = rv;
+			break;
+
 		case 'b':
 			opt->benchmark = 1;
 			break;
@@ -540,7 +569,8 @@ make_processing_chain(struct gapk_state *gs)
 	if (gs->in.file.fh)
 		osmo_gapk_pq_queue_file_input(gs->pq, gs->in.file.fh, fmt_in->frame_len);
 	else if (gs->in.rtp.fd != -1)
-		osmo_gapk_pq_queue_rtp_input(gs->pq, gs->in.rtp.fd, fmt_in->frame_len);
+		osmo_gapk_pq_queue_rtp_input(gs->pq, gs->in.rtp.fd,
+			fmt_in->frame_len, gs->opts.rtp_pt_in);
 #ifdef HAVE_ALSA
 	else if (gs->opts.alsa_in)
 		osmo_gapk_pq_queue_alsa_input(gs->pq, gs->opts.alsa_in, fmt_in->frame_len);
@@ -618,7 +648,8 @@ make_processing_chain(struct gapk_state *gs)
 	if (gs->out.file.fh)
 		osmo_gapk_pq_queue_file_output(gs->pq, gs->out.file.fh, fmt_out->frame_len);
 	else if (gs->out.rtp.fd != -1)
-		osmo_gapk_pq_queue_rtp_output(gs->pq, gs->out.rtp.fd, fmt_out->frame_len);
+		osmo_gapk_pq_queue_rtp_output(gs->pq, gs->out.rtp.fd,
+			fmt_out->frame_len, gs->opts.rtp_pt_out);
 #ifdef HAVE_ALSA
 	else if (gs->opts.alsa_out)
 		osmo_gapk_pq_queue_alsa_output(gs->pq, gs->opts.alsa_out, fmt_out->frame_len);
diff --git a/src/pq_rtp.c b/src/pq_rtp.c
index a50013a..81eeb19 100644
--- a/src/pq_rtp.c
+++ b/src/pq_rtp.c
@@ -70,8 +70,6 @@ struct rtp_x_hdr {
 
 #define RTP_VERSION	2
 
-#define RTP_PT_GSM_FULL 3
-
 struct pq_state_rtp {
 	int fd;
 	int blk_len;
@@ -193,7 +191,8 @@ pq_cb_rtp_exit(void *_state)
 }
 
 static int
-pq_queue_rtp_op(struct osmo_gapk_pq *pq, int udp_fd, unsigned int blk_len, int in_out_n)
+pq_queue_rtp_op(struct osmo_gapk_pq *pq, int udp_fd,
+	unsigned int blk_len, int in_out_n, uint8_t pt)
 {
 	struct osmo_gapk_pq_item *item;
 	struct pq_state_rtp *state;
@@ -210,12 +209,20 @@ pq_queue_rtp_op(struct osmo_gapk_pq *pq, int udp_fd, unsigned int blk_len, int i
 	 * per RTP frame */
 	state->duration = 160;
 
+	/**
+	 * RTP payload type according to RFC 3551,
+	 * section "6. Payload Type Definitions".
+	 *
+	 * Only GSM FR has a static payload type value (see table 4).
+	 * For other codecs the payload type may be negotiated
+	 * between the both sides dynamically (i.e. in range 96-127).
+	 */
+	state->payload_type = pt;
+
 	if (in_out_n == 0) {
 		state->ssrc = rand();
 		state->sequence = random();
 		state->timestamp = random();
-		/* FIXME: other payload types!! */
-		state->payload_type = RTP_PT_GSM_FULL;
 	}
 
 	item = osmo_gapk_pq_add_item(pq);
@@ -248,24 +255,30 @@ pq_queue_rtp_op(struct osmo_gapk_pq *pq, int udp_fd, unsigned int blk_len, int i
  *  This typically only makes sense as first item in the queue
  *  \param pq Processing Queue to add this RTP input to
  *  \param[in] udp_fd UDP file descriptor for the RTP input
- *  \param[in] blk_len Block Length to read from RTP */
+ *  \param[in] blk_len Block Length to read from RTP
+ *  \param[in] pt Payload type according to RFC 3551
+ */
 int
-osmo_gapk_pq_queue_rtp_input(struct osmo_gapk_pq *pq, int udp_fd, unsigned int blk_len)
+osmo_gapk_pq_queue_rtp_input(struct osmo_gapk_pq *pq, int udp_fd,
+	unsigned int blk_len, uint8_t pt)
 {
 	LOGPGAPK(LOGL_DEBUG, "PQ '%s': Adding RTP input (blk_len=%u)\n",
 		pq->name, blk_len);
-	return pq_queue_rtp_op(pq, udp_fd, blk_len, 1);
+	return pq_queue_rtp_op(pq, udp_fd, blk_len, 1, pt);
 }
 
 /*! Add RTP output to processing queue.
  *  This typically only makes sense as last item in the queue
  *  \param pq Processing Queue to add this RTP output to
  *  \param[in] udp_fd UDP file descriptor for the RTP output
- *  \param[in] blk_len Block Length to read from RTP */
+ *  \param[in] blk_len Block Length to read from RTP
+ *  \param[in] pt Payload type according to RFC 3551
+ */
 int
-osmo_gapk_pq_queue_rtp_output(struct osmo_gapk_pq *pq, int udp_fd, unsigned int blk_len)
+osmo_gapk_pq_queue_rtp_output(struct osmo_gapk_pq *pq, int udp_fd,
+	unsigned int blk_len, uint8_t pt)
 {
 	LOGPGAPK(LOGL_DEBUG, "PQ '%s': Adding RTP output (blk_len=%u)\n",
 		pq->name, blk_len);
-	return pq_queue_rtp_op(pq, udp_fd, blk_len, 0);
+	return pq_queue_rtp_op(pq, udp_fd, blk_len, 0, pt);
 }
diff --git a/tests/io/pq_rtp_test.c b/tests/io/pq_rtp_test.c
index 2c1bd41..76f59d2 100644
--- a/tests/io/pq_rtp_test.c
+++ b/tests/io/pq_rtp_test.c
@@ -173,7 +173,7 @@ static int init_gen_queue(struct osmo_gapk_pq *pq,
 	}
 
 	/* Init an RTP sink */
-	rc = osmo_gapk_pq_queue_rtp_output(pq, state->rtp_dst_fd, payload_len);
+	rc = osmo_gapk_pq_queue_rtp_output(pq, state->rtp_dst_fd, payload_len, 0x00);
 	if (rc) {
 		printf("Could not init an RTP sink\n");
 		return rc;
@@ -210,7 +210,7 @@ static int init_chk_queue(struct osmo_gapk_pq *pq,
 	}
 
 	/* Init an RTP source on any available port */
-	rc = osmo_gapk_pq_queue_rtp_input(pq, state->rtp_src_fd, payload_len);
+	rc = osmo_gapk_pq_queue_rtp_input(pq, state->rtp_src_fd, payload_len, 0x00);
 	if (rc) {
 		printf("Could not init an RTP sink\n");
 		return rc;