[M] Change in libosmo-abis[master]: TRAU->RTP: add support for TW-TS-001 & TW-TS-002 - gerrit-log

11 Jun 2024

falconia has submitted this change. ( https://gerrit.osmocom.org/c/libosmo-abis/+/37156?usp=email )
Change subject: TRAU->RTP: add support for TW-TS-001 & TW-TS-002
......................................................................
TRAU->RTP: add support for TW-TS-001 & TW-TS-002
The industry standard RTP payload formats of RFC 3551 and RFC 5993
drop valuable metadata from TRAU-UL frames of GSM 08.60 & 08.61,
and disallow transport of marked-bad frames.  Enhanced RTP transport
formats of TW-TS-001 (FR & EFR) and TW-TS-002 (HR) restore these
capabilities - however, because these formats are non-standard
outside of Osmocom+Themyscira GSM networks, their use can only be
optional.
Add rtp_extensions member to struct osmo_trau2rtp_state, specifying
the mask of RTP extensions to be used, just like we defined for
AoIP BSSMAP and Abis-IP RSL, and extend osmo_trau2rtp() to emit
these enhanced RTP formats when they are enabled.
Related: OS#6448
Depends: I0eccfe5ddcf44f8f20440acb01e2d4870ec0cd91 (libosmocore)
Change-Id: I7a6d13d406484c01210594bb6d2f0aff7c1341ab
---
M TODO-RELEASE
M include/osmocom/trau/trau_rtp.h
M src/trau/trau_rtp_conv.c
3 files changed, 135 insertions(+), 29 deletions(-)
Approvals:
  fixeria: Looks good to me, but someone else must approve
  pespin: Looks good to me, approved
  Jenkins Builder: Verified

diff --git a/TODO-RELEASE b/TODO-RELEASE
index d0852fc..e3ad20a 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -7,3 +7,5 @@
 # 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
+libosmotrau	struct osmo_trau2rtp_state extended (ABI break)
+libosmogsm	>1.9.0		rtp_extensions.h new header
diff --git a/include/osmocom/trau/trau_rtp.h b/include/osmocom/trau/trau_rtp.h
index f02d43e..6b2110f 100644
--- a/include/osmocom/trau/trau_rtp.h
+++ b/include/osmocom/trau/trau_rtp.h
@@ -24,6 +24,7 @@
struct osmo_trau2rtp_state {
    enum osmo_trau_frame_type type;
+	uint8_t rtp_extensions;
 };
diff --git a/src/trau/trau_rtp_conv.c b/src/trau/trau_rtp_conv.c
index b8f554c..d3d1cae 100644
--- a/src/trau/trau_rtp_conv.c
+++ b/src/trau/trau_rtp_conv.c
@@ -26,6 +26,7 @@
#include <osmocom/core/crc8gen.h>
 #include <osmocom/codec/codec.h>
+#include <osmocom/gsm/rtp_extensions.h>
#include <osmocom/trau/trau_frame.h>
 #include <osmocom/trau/trau_rtp.h>
@@ -100,20 +101,34 @@
  *  \param[in] out_len length of out buffer in bytes
  *  \param[in] fr input TRAU frame in decoded form
  *  \returns number of bytes generated in 'out'; negative on error. */
-static int trau2rtp_fr(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf)
+static int trau2rtp_fr(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf, bool emit_twts001)
 {
+	size_t req_out_len = emit_twts001 ? GSM_FR_BYTES+1 : GSM_FR_BYTES;
    int i, j, k, l, o;
if (tf->type != OSMO_TRAU16_FT_FR)
    	return -EINVAL;
+	if (out_len < req_out_len)
+		return -ENOSPC;
+
    /* FR Data Bits according to TS 48.060 Section 5.5.1.1.2 */
-	if (tf->c_bits[11]) /* BFI */
-		return 0;
+	/* Are we emitting TW-TS-001? If so, emit TRAU-like Extension Header */
+	if (emit_twts001) {
+		uint8_t hdr_byte = 0xE0;
-	if (out_len < GSM_FR_BYTES)
-		return -ENOSPC;
+		if (tf->c_bits[16])	/* DTXd */
+			hdr_byte |= 0x08;
+		if (tf->c_bits[11])	/* BFI */
+			hdr_byte |= 0x02;
+		if (tf->c_bits[14])	/* TAF */
+			hdr_byte |= 0x01;
+		*out++ = hdr_byte;
+	}
+
+	if (tf->c_bits[11] && !emit_twts001) /* BFI without TW-TS-001 */
+		return 0;
out[0] = 0xd << 4;
    /* reassemble d-bits */
@@ -135,18 +150,30 @@
    	j++;
    }
-	return GSM_FR_BYTES;
+	return req_out_len;
 }
-/* See Section 5.2 of RFC5993 */
-enum rtp_hr_ietf_ft {
-	FT_GOOD_SPEECH  = 0,
-	FT_GOOD_SID     = 2,
-	FT_NO_DATA      = 7,
+/* See Section 5.2 of RFC5993 and TW-TS-002 */
+enum super5993_ft {
+	FT_GOOD_SPEECH		= 0,
+	FT_INVALID_SID		= 1,
+	FT_GOOD_SID		= 2,
+	FT_BFI_WITH_DATA	= 6,
+	FT_NO_DATA		= 7,
 };
static const uint8_t rtp_hr_sid[14] = { 0x00, 0x00, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
+static void twtw002_hr16_set_extra_flags(uint8_t *out, const struct osmo_trau_frame *tf)
+{
+	if (tf->c_bits[16])	/* DTXd */
+		out[0] |= 0x08;
+	if (tf->ufi)		/* UFI */
+		out[0] |= 0x02;
+	if (tf->c_bits[14])	/* TAF */
+		out[0] |= 0x01;
+}
+
 /*! Generate an RFC 5993 RTP payload for HR from a decoded 16k TRAU frame.
  *  We previously emitted TS 101 318 format; however, RFC 5993 is the format
  *  specified in TS 48.103 for AoIP, it can also be extended with TRAU-UL-like
@@ -156,7 +183,7 @@
  *  \param[in] out_len length of out buffer in bytes
  *  \param[in] tf input TRAU frame in decoded form
  *  \returns number of bytes generated in 'out'; negative on error. */
-static int trau2rtp_hr16(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf)
+static int trau2rtp_hr16(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf, bool emit_twts002)
 {
    enum osmo_gsm631_sid_class sidc;
@@ -175,26 +202,46 @@
/* Plain RFC 5993 without TW-TS-002 extensions does not allow
     * BFI or invalid SID packets. */
-	if (tf->c_bits[11] || sidc == OSMO_GSM631_SID_CLASS_INVALID)
+	if (!emit_twts002 &&
+	    (tf->c_bits[11] || sidc == OSMO_GSM631_SID_CLASS_INVALID))
    	goto bad_frame;
+	/* BFI turns valid SID into invalid */
+	if (tf->c_bits[11] && sidc == OSMO_GSM631_SID_CLASS_VALID)
+		sidc = OSMO_GSM631_SID_CLASS_INVALID;
+
    /* RFC 5993 Frame Type is equal to GSM 06.41 SID classification,
-	 * restricted to just speech or valid SID per above. */
+	 * restricted to just speech or valid SID per above.  Or if we
+	 * emit TW-TS-002, that restriction is lifted. */
    out[0] = sidc << 4;
+	if (emit_twts002) {
+		if (tf->c_bits[11] && sidc == OSMO_GSM631_SID_CLASS_SPEECH)
+			out[0] = FT_BFI_WITH_DATA << 4;
+		twtw002_hr16_set_extra_flags(out, tf);
+		/* invalid SID frames are truncated in TW-TS-002 */
+		if (sidc == OSMO_GSM631_SID_CLASS_INVALID)
+			return 1;
+	}
+
    /* TS 101 318 Section 5.2: The order of occurrence of the codec parameters in the buffer is
     * the same as order of occurrence over the Abis as defined in annex B of ETS 300 969
     * [which is 3GPP TS 46.020 */
    osmo_ubit2pbit(out + 1, tf->d_bits, 112);
/* RFC 5993 requires SID frames to be perfect, error-free */
-	if (sidc == OSMO_GSM631_SID_CLASS_VALID)
+	if (!emit_twts002 && sidc == OSMO_GSM631_SID_CLASS_VALID)
    	osmo_hr_sid_reset(out + 1);
return GSM_HR_BYTES_RTP_RFC5993;
bad_frame:
-	return 0;
+	if (emit_twts002) {
+		out[0] = FT_NO_DATA << 4;
+		twtw002_hr16_set_extra_flags(out, tf);
+		return 1;
+	} else
+		return 0;
 }
/*! Generate the 31 bytes RTP payload for GSM-EFR from a decoded TRAU frame.
@@ -202,25 +249,36 @@
  *  \param[in] out_len length of out buffer in bytes
  *  \param[in] fr input TRAU frame in decoded form
  *  \returns number of bytes generated in 'out'; negative on error. */
-static int trau2rtp_efr(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf)
+static int trau2rtp_efr(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf, bool emit_twts001)
 {
+	size_t req_out_len = emit_twts001 ? GSM_EFR_BYTES+1 : GSM_EFR_BYTES;
    int i, j, rc;
    ubit_t check_bits[26];
+	uint8_t *twts001_hdr;
+
+	if (out_len < req_out_len)
+		return -ENOSPC;
if (tf->type != OSMO_TRAU16_FT_EFR)
    	return -EINVAL;
/* FR Data Bits according to TS 48.060 Section 5.5.1.1.2 */
-	if (tf->c_bits[11]) /* BFI */
+	/* Are we emitting TW-TS-001? If so, emit TRAU-like Extension Header */
+	if (emit_twts001) {
+		twts001_hdr = out++;
+		*twts001_hdr = 0xE0;
+		if (tf->c_bits[16])	/* DTXd */
+			*twts001_hdr |= 0x08;
+		if (tf->c_bits[11])	/* BFI */
+			*twts001_hdr |= 0x02;
+		if (tf->c_bits[14])	/* TAF */
+			*twts001_hdr |= 0x01;
+	}
+
+	if (tf->c_bits[11] && !emit_twts001) /* BFI without TW-TS-001 */
    	return 0;
-	if (out_len < GSM_EFR_BYTES)
-		return -ENOSPC;
-
-	if (tf->c_bits[11]) /* BFI */
-		goto bad_frame;
-
    out[0] = 0xc << 4;
    /* reassemble d-bits */
    for (i = 1, j = 4; i < 39; i++, j++)
@@ -259,9 +317,14 @@
    if (rc)
    	goto bad_frame;
-	return GSM_EFR_BYTES;
+	return req_out_len;
+
 bad_frame:
-	return 0;
+	if (emit_twts001) {
+		*twts001_hdr |= 0x06;	/* BFI and No_Data flags */
+		return 1;
+	} else
+		return 0;
 }
/* TS 48.060 Section 5.5.1.1.2 */
@@ -722,16 +785,32 @@
 }
 #endif
+static inline bool check_twts001(struct osmo_trau2rtp_state *st)
+{
+	if (st->rtp_extensions & OSMO_RTP_EXT_TWTS001)
+		return true;
+	else
+		return false;
+}
+
+static inline bool check_twts002(struct osmo_trau2rtp_state *st)
+{
+	if (st->rtp_extensions & OSMO_RTP_EXT_TWTS002)
+		return true;
+	else
+		return false;
+}
+
 int osmo_trau2rtp(uint8_t *out, size_t out_len, const struct osmo_trau_frame *tf,
    	  struct osmo_trau2rtp_state *st)
 {
    switch (tf->type) {
    case OSMO_TRAU16_FT_FR:
-		return trau2rtp_fr(out, out_len, tf);
+		return trau2rtp_fr(out, out_len, tf, check_twts001(st));
    case OSMO_TRAU16_FT_EFR:
-		return trau2rtp_efr(out, out_len, tf);
+		return trau2rtp_efr(out, out_len, tf, check_twts001(st));
    case OSMO_TRAU16_FT_HR:
-		return trau2rtp_hr16(out, out_len, tf);
+		return trau2rtp_hr16(out, out_len, tf, check_twts002(st));
    default:
    	return -EINVAL;
    }
-- 
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Gerrit-Project: libosmo-abis
Gerrit-Branch: master
Gerrit-Change-Id: I7a6d13d406484c01210594bb6d2f0aff7c1341ab
Gerrit-Change-Number: 37156
Gerrit-PatchSet: 5
Gerrit-Owner: falconia falcon@freecalypso.org
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: falconia falcon@freecalypso.org
Gerrit-Reviewer: fixeria vyanitskiy@sysmocom.de
Gerrit-Reviewer: pespin pespin@sysmocom.de
Gerrit-MessageType: merged



    