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MGW control: migrate to new API for fmtp

Some codecs have additional parameters that need to be communicated
to the MGW using fmtp lines in SDP.  We use this mechanism to
indicate octet-align=0|1 for AMR and signal the use of TW-TS-001
and TW-TS-002 extensions for FR/EFR and HR, respectively.
Migrate from legacy struct mgcp_codec_param (now deprecated)
to the new fmtp string API.

Depends: I84ba2ed5ab9d379ac0b675520796446ad6ee0710 (osmo-mgw.git)
Change-Id: Id869c9fa33a3ca6fecd30d5630741fbbf21cf6ed
---
M TODO-RELEASE
M src/osmo-bsc/lchan_rtp_fsm.c
2 files changed, 27 insertions(+), 45 deletions(-)

diff --git a/TODO-RELEASE b/TODO-RELEASE
index 0ed7189..1d65ba1 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -7,3 +7,4 @@
 # If any interfaces have been added since the last public release: c:r:a + 1.
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what			description / commit summary line
+libosmo-mgcp-client	>1.15.0		new API of fmtp in struct ptmap
diff --git a/src/osmo-bsc/lchan_rtp_fsm.c b/src/osmo-bsc/lchan_rtp_fsm.c
index c348833..8095378 100644
--- a/src/osmo-bsc/lchan_rtp_fsm.c
+++ b/src/osmo-bsc/lchan_rtp_fsm.c
@@ -947,7 +947,7 @@
 {
 	enum mgcp_codecs codec = chan_mode_to_mgcp_codec(lchan->activate.ch_mode_rate.chan_mode,
 							 lchan->type == GSM_LCHAN_TCH_H? false : true);
-	int pt;
+	int pt, amr_oa;
 
 	if (codec < 0) {
 		LOG_LCHAN(lchan, LOGL_ERROR,
@@ -980,51 +980,32 @@
 	verb_info->ptmap[0].pt = pt;
 	verb_info->ptmap_len = 1;
 
-	/* AMR requires additional parameters to be set up (framing mode) */
-	if (codec == CODEC_AMR_8000_1) {
-		verb_info->param_present = true;
-		verb_info->param.amr_octet_aligned_present = true;
-	}
-
-	if (bss_side && codec == CODEC_AMR_8000_1) {
-		/* FIXME: At the moment all BTSs we support are using the
-		 * octet-aligned payload format. However, in the future
-		 * we may support BTSs that are using bandwidth-efficient
-		 * format. In this case we will have to add functionality
-		 * that distinguishes by the BTS model which mode to use. */
-		verb_info->param.amr_octet_aligned = true;
-	}
-	else if (!bss_side && codec == CODEC_AMR_8000_1) {
-		verb_info->param.amr_octet_aligned = lchan->conn->sccp.msc->amr_octet_aligned;
-	}
-
-	/* If the CN has requested RTP payload format extensions (change from
-	 * RFC 3551 to TW-TS-001 for FR/EFR, or from RFC 5993 to TW-TS-002
-	 * for HRv1) via BSSMAP IE of TW-TS-003, we need to pass this request
-	 * to the MGW.  With E1 BTS our MGW is the origin of the RTP stream
-	 * and thus the party responsible for payload format choices; with
-	 * IP BTS our MGW is merely a forwarder and thus can get by without
-	 * this detailed knowledge, but it doesn't hurt to inform the MGW
-	 * in all cases.
-	 *
-	 * Note that the following code does not perform conditional checks
-	 * of whether the selected codec is FR/EFR for TW-TS-001 or HRv1
-	 * for TW-TS-002, but instead checks only the extension mode bits.
-	 * This simplification is allowed by libosmo-mgcp-client API:
-	 * struct mgcp_codec_param has dedicated fields for fr_efr_twts001
-	 * and hr_twts002 parameters, and the code in libosmo-mgcp-client
-	 * then emits the corresponding a=fmtp lines only when the SDP
-	 * includes those codecs to which these attributes apply.
+	/* Some codecs require fmtp parameters, either always (AMR)
+	 * or conditionally (FR & EFR with TW-TS-001, HR with TW-TS-002).
+	 * Use the new fmtp string API to insert them into our outgoing
+	 * CRCX/MDCX.
 	 */
-	if (lchan->conn->user_plane.rtp_extensions & OSMO_RTP_EXT_TWTS001) {
-		verb_info->param_present = true;
-		verb_info->param.fr_efr_twts001_present = true;
-		verb_info->param.fr_efr_twts001 = true;
-	}
-	if (lchan->conn->user_plane.rtp_extensions & OSMO_RTP_EXT_TWTS002) {
-		verb_info->param_present = true;
-		verb_info->param.hr_twts002_present = true;
-		verb_info->param.hr_twts002 = true;
+	switch (codec) {
+	case CODEC_AMR_8000_1:
+		if (bss_side)
+			amr_oa = 1;
+		else
+			amr_oa = lchan->conn->sccp.msc->amr_octet_aligned;
+		snprintf(verb_info->ptmap[0].fmtp,
+			 sizeof(verb_info->ptmap[0].fmtp),
+			 "octet-align=%d", amr_oa);
+		break;
+	case CODEC_GSM_8000_1:
+	case CODEC_GSMEFR_8000_1:
+		if (lchan->conn->user_plane.rtp_extensions & OSMO_RTP_EXT_TWTS001)
+			OSMO_STRLCPY_ARRAY(verb_info->ptmap[0].fmtp, "tw-ts-001=1");
+		break;
+	case CODEC_GSMHR_8000_1:
+		if (lchan->conn->user_plane.rtp_extensions & OSMO_RTP_EXT_TWTS002)
+			OSMO_STRLCPY_ARRAY(verb_info->ptmap[0].fmtp, "tw-ts-002=1");
+		break;
+	default:
+		break;
 	}
 }
 

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