falconia has uploaded this change for review. (
https://gerrit.osmocom.org/c/libosmo-abis/+/37287?usp=email )
Change subject: trau_rtp_conv: add support for HRv1 in 8k format
......................................................................
trau_rtp_conv: add support for HRv1 in 8k format
GSM 08.61 defines two alternative Abis transport formats for
HRv1 codec, using either 16 kbit/s or 8 kbit/s submultiplexing,
as chosen by each BSS hardware manufacturer. libosmotrau previously
supported TRAU<->RTP conversion only for 16k format - add support
for HRv1 in 8k submux format.
Change-Id: I8ee01b73360501ca380a8695cbc7070ceaaba1be
---
M src/trau/trau_rtp_conv.c
1 file changed, 188 insertions(+), 0 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmo-abis refs/changes/87/37287/1
diff --git a/src/trau/trau_rtp_conv.c b/src/trau/trau_rtp_conv.c
index 91bf228..0dcd1b0 100644
--- a/src/trau/trau_rtp_conv.c
+++ b/src/trau/trau_rtp_conv.c
@@ -249,6 +249,112 @@
return 0;
}
+static bool hr8_xc_bits_good_parity(const ubit_t *xc_bits)
+{
+ int i;
+ unsigned int sum = 0;
+
+ for (i = 0; i < 6; i++) {
+ if (xc_bits[i])
+ sum++;
+ }
+ if (sum & 1)
+ return true; /* odd sum good */
+ else
+ return false; /* even sum bad */
+}
+
+static void twts002_hr8_set_extra_flags(uint8_t *out, const struct
osmo_trau_frame *tf)
+{
+ if (tf->c_bits[8]) /* DTXd */
+ out[0] |= 0x08;
+ if (tf->xc_bits[4]) /* UFI */
+ out[0] |= 0x02;
+}
+
+/*! Generate an RFC 5993 or TW-TS-002 RTP payload for HRv1
+ * from a decoded 8k TRAU frame.
+ * \param[out] out caller-provided output buffer
+ * \param[in] out_len length of out buffer in bytes
+ * \param[in] tf input TRAU frame in decoded form
+ * \param[in] emit_twts002 self-explanatory
+ * \returns number of bytes generated in 'out'; negative on error. */
+static int trau2rtp_hr8(uint8_t *out, size_t out_len,
+ const struct osmo_trau_frame *tf, bool emit_twts002)
+{
+ unsigned xc1_4;
+
+ /* function interface preliminaries */
+ if (tf->type != OSMO_TRAU8_SPEECH)
+ return -EINVAL;
+ if (out_len < GSM_HR_BYTES_RTP_RFC5993)
+ return -ENOSPC;
+
+ /* Before considering anything else, if we have bad parity in
+ * frame classification bits or bad CRC in payload bits,
+ * we treat this frame as totally invalid: BFI with no data. */
+ if (!hr8_xc_bits_good_parity(tf->xc_bits) ||
+ osmo_crc8gen_check_bits(&gsm0860_efr_crc3, tf->d_bits, 44,
+ tf->crc_bits))
+ goto bad_frame;
+
+ /* classify this frame per XC1..XC4 */
+ xc1_4 = (tf->xc_bits[0] << 3) | (tf->xc_bits[1] << 2) |
+ (tf->xc_bits[2] << 1) | (tf->xc_bits[3] << 0);
+ switch (xc1_4) {
+ case 0:
+ /* good speech frame (BFI=0, SID=0) */
+ out[0] = FT_GOOD_SPEECH << 4;
+ if (emit_twts002)
+ twts002_hr8_set_extra_flags(out, tf);
+ osmo_ubit2pbit(out + 1, tf->d_bits, 112);
+ return GSM_HR_BYTES_RTP_RFC5993;
+ case 1:
+ /* valid SID frame (BFI=0, SID=2) */
+ out[0] = FT_GOOD_SID << 4;
+ if (emit_twts002)
+ twts002_hr8_set_extra_flags(out, tf);
+ osmo_ubit2pbit(out + 1, tf->d_bits, 112);
+ /* RFC 5993 requires SID frames to be perfect, error-free */
+ if (!emit_twts002)
+ osmo_hr_sid_reset(out + 1);
+ return GSM_HR_BYTES_RTP_RFC5993;
+ case 4:
+ case 5:
+ /* invalid SID frame (multiple BFI/SID combinations) */
+ /* can be represented only in TW-TS-002, not in RFC 5993 */
+ if (!emit_twts002)
+ return 0;
+ out[0] = FT_INVALID_SID << 4;
+ twts002_hr8_set_extra_flags(out, tf);
+ /* XC4 is TAF with this frame type */
+ if (tf->xc_bits[3])
+ out[0] |= 0x01;
+ return 1; /* short format per TW-TS-002 */
+ case 6:
+ case 7:
+ /* bad speech frame (BFI=1, SID=0) */
+ if (!emit_twts002)
+ return 0;
+ out[0] = FT_BFI_WITH_DATA << 4;
+ twts002_hr8_set_extra_flags(out, tf);
+ /* XC4 is TAF with this frame type */
+ if (tf->xc_bits[3])
+ out[0] |= 0x01;
+ osmo_ubit2pbit(out + 1, tf->d_bits, 112);
+ return GSM_HR_BYTES_RTP_RFC5993;
+ default:
+ bad_frame:
+ /* received garbage, emit BFI with no data */
+ if (emit_twts002) {
+ out[0] = FT_NO_DATA << 4;
+ twts002_hr8_set_extra_flags(out, tf);
+ return 1;
+ } else
+ return 0;
+ }
+}
+
/*! Generate the 31 bytes RTP payload for GSM-EFR from a decoded TRAU frame.
* \param[out] out caller-provided output buffer
* \param[in] out_len length of out buffer in bytes
@@ -524,6 +630,69 @@
return 0;
}
+static int rtp2trau_hr8(struct osmo_trau_frame *tf, const uint8_t *data,
size_t data_len)
+{
+ /* accept both TS 101 318 and RFC 5993 payloads */
+ switch (data_len) {
+ case GSM_HR_BYTES:
+ break;
+ case GSM_HR_BYTES_RTP_RFC5993:
+ data++;
+ data_len--;
+ break;
+ case 0:
+ /* accept no-data input */
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* FIXME: implement TRAU-UL frame generation if and when
+ * someone actually needs it in a program that uses
+ * this library. */
+ if (tf->dir != OSMO_TRAU_DIR_DL)
+ return -ENOTSUP;
+
+ tf->type = OSMO_TRAU8_SPEECH;
+
+ /* C1..C5 */
+ tf->c_bits[0] = 0;
+ tf->c_bits[1] = 0;
+ tf->c_bits[2] = 0;
+ tf->c_bits[3] = 1; /* UFE: good uplink */
+ tf->c_bits[4] = 0; /* odd parity */
+ /* C6..C9: spare bits */
+ memset(tf->c_bits + 5, 1, 4);
+
+ /* XC1..XC6 */
+ if (osmo_hr_check_sid(data, data_len)) {
+ tf->xc_bits[0] = 0;
+ tf->xc_bits[1] = 0;
+ tf->xc_bits[2] = 0;
+ tf->xc_bits[3] = 1;
+ tf->xc_bits[4] = 0;
+ tf->xc_bits[5] = 0; /* odd parity */
+ } else {
+ tf->xc_bits[0] = 0;
+ tf->xc_bits[1] = 0;
+ tf->xc_bits[2] = 0;
+ tf->xc_bits[3] = 0;
+ tf->xc_bits[4] = 0;
+ tf->xc_bits[5] = 1; /* odd parity */
+ }
+
+ memset(&tf->t_bits[0], 1, 2);
+
+ if (data_len)
+ osmo_pbit2ubit(tf->d_bits, data, GSM_HR_BYTES * 8);
+ else
+ memset(tf->d_bits, 0, GSM_HR_BYTES * 8);
+ /* CRC is *not* computed by TRAU frame encoder - we have to do it */
+ osmo_crc8gen_set_bits(&gsm0860_efr_crc3, tf->d_bits, 44, tf->crc_bits);
+
+ return 0;
+}
+
/* TS 48.060 Section 5.5.1.1.2 */
static int rtp2trau_efr(struct osmo_trau_frame *tf, const uint8_t *data,
size_t data_len)
{
@@ -801,6 +970,8 @@
return trau2rtp_efr(out, out_len, tf, check_twts001(st));
case OSMO_TRAU16_FT_HR:
return trau2rtp_hr16(out, out_len, tf, check_twts002(st));
+ case OSMO_TRAU8_SPEECH:
+ return trau2rtp_hr8(out, out_len, tf, check_twts002(st));
default:
return -EINVAL;
}
@@ -816,6 +987,8 @@
return rtp2trau_efr(tf, rtp, rtp_len);
case OSMO_TRAU16_FT_HR:
return rtp2trau_hr16(tf, rtp, rtp_len);
+ case OSMO_TRAU8_SPEECH:
+ return rtp2trau_hr8(tf, rtp, rtp_len);
default:
return -EINVAL;
}
--
To view, visit https://gerrit.osmocom.org/c/libosmo-abis/+/37287?usp=email
To unsubscribe, or for help writing mail filters, visit
https://gerrit.osmocom.org/settings
Gerrit-Project: libosmo-abis
Gerrit-Branch: master
Gerrit-Change-Id: I8ee01b73360501ca380a8695cbc7070ceaaba1be
Gerrit-Change-Number: 37287
Gerrit-PatchSet: 1
Gerrit-Owner: falconia <fal...@freecalypso.org>
Gerrit-MessageType: newchange
