fixeria submitted this change.
osmo-bts-trx: rx_tchh_fn(): fix HR SID detection (wrong offset)
According to RFC5993, which is referenced by 3GPP TS 48.103, the
complete RTP HR payload consists of a Table-of-Contents (ToC) byte
followed by the 14 bytes of the HR codec frame. See section 5.2.
gsm0503_tch_hr_decode() outputs frames in the RTP format with
length of 15 bytes (120 bits): 1 (ToC) + 14 (HR frame):
+-------------+-------------------------
| ToC section | HR codec frame ...
+-------------+-------------------------
osmo_hr_check_sid() expects a HR codec frame of 14 bytes (112 bits)
as the input, so we should skip the ToC section when calling it.
Change-Id: Ie5fa776dcb2b2203a97aed56ecbf2450af7d87c1
Related: SYS#5853
---
M src/osmo-bts-trx/sched_lchan_tchh.c
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/src/osmo-bts-trx/sched_lchan_tchh.c b/src/osmo-bts-trx/sched_lchan_tchh.c
index b6d83d0..d2ee4f0 100644
--- a/src/osmo-bts-trx/sched_lchan_tchh.c
+++ b/src/osmo-bts-trx/sched_lchan_tchh.c
@@ -147,8 +147,10 @@
*/
rc = gsm0503_tch_hr_decode(tch_data, *bursts_p,
fn_is_odd, &n_errors, &n_bits_total);
- if (rc == (GSM_HR_BYTES + 1)) /* only for valid *speech* frames */
- lchan_set_marker(osmo_hr_check_sid(tch_data, rc), lchan); /* DTXu */
+ if (rc == (GSM_HR_BYTES + 1)) { /* only for valid *speech* frames */
+ /* gsm0503_tch_hr_decode() prepends a ToC octet (see RFC5993), skip it */
+ lchan_set_marker(osmo_hr_check_sid(&tch_data[1], GSM_HR_BYTES), lchan); /* DTXu */
+ }
break;
case GSM48_CMODE_SPEECH_AMR: /* AMR */
/* the first FN 0,8,17 or 1,9,18 defines that CMI is included
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