Attention is currently required from: pespin, dexter. Hello Jenkins Builder, I'd like you to reexamine a change. Please visit https://gerrit.osmocom.org/c/osmo-bts/+/32714 to look at the new patch set (#4). Change subject: TCH DL, FR & EFR: reshape SIDs per 06.31/06.81 section 5.1.2 ...................................................................... TCH DL, FR & EFR: reshape SIDs per 06.31/06.81 section 5.1.2 Section 5.1.2 of GSM 06.31 & 06.81 (DTX specs for FR & EFR) specifies the expected shape of radio downlink in the presence of SIDs: one SID frame after each talkspurt (after speech frames), and one SID frame in every SACCH-aligned position every 480 ms, or if the actual SACCH- aligned position is taken up by FACCH, then just one SID frame as soon as possible after that FACCH - and no transmitted SID frames in other positions. This just-referenced spec section was written with the assumption that it will only be applied when DTXd is enabled - however, if the RTP stream for call leg B DL comes from call leg A UL (TrFO), then we are going to receive SID frames in the stream intended for our DL even when DTXd is disabled or not supported altogether. The easiest solution is to apply FR/EFR (and in the future HR1 too) DTXd logic whenever the incoming RTP stream contains SID frames, irrespective of physical DTXd enable/disable state. If we apply such "logical DTXd" when physical DTXd is disabled, the BTS model PHY will end up transmitting induced BFIs (dummy FACCH or inverted CRC3) in those frame positions where the "logical DTXd" function says "please transmit nothing". The point remains, however, that the prescribed SID shape on the radio downlink (expected positions of SID frames) won't happen on its own: in the case of TrFO, whichever SID frames are present will be in wrong positions for leg B DL, and even in the case of transcoded calls the responsibility for DL SID shaping cannot be placed on the RTP stream source because that source won't know where SACCH alignment will lie. Therefore, the necessary DL SID reshaping has to be done in the RTP stream receiver in OsmoBTS. Related: OS#5996 Change-Id: I924ab21952dcf8bb03ba7ccef790474bf66fc9e5 --- M include/osmo-bts/lchan.h M src/common/l1sap.c 2 files changed, 228 insertions(+), 0 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/14/32714/4 -- To view, visit https://gerrit.osmocom.org/c/osmo-bts/+/32714 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-bts Gerrit-Branch: master Gerrit-Change-Id: I924ab21952dcf8bb03ba7ccef790474bf66fc9e5 Gerrit-Change-Number: 32714 Gerrit-PatchSet: 4 Gerrit-Owner: falconia <falcon(a)freecalypso.org> Gerrit-Reviewer: Jenkins Builder Gerrit-CC: dexter <pmaier(a)sysmocom.de> Gerrit-CC: pespin <pespin(a)sysmocom.de> Gerrit-Attention: pespin <pespin(a)sysmocom.de> Gerrit-Attention: dexter <pmaier(a)sysmocom.de> Gerrit-MessageType: newpatchset