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Hello Jenkins Builder, fixeria, pespin,

I'd like you to reexamine a change. Please visit

https://gerrit.osmocom.org/c/osmo-bts/+/38554?usp=email

to look at the new patch set (#4).

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Change subject: csd_v110: set E2 bit correctly for TCH/[FH]4.8 NT ......................................................................

csd_v110: set E2 bit correctly for TCH/[FH]4.8 NT

In all classic NT modes below 14.5 kbit/s, V.110 frame bits E2 and E3 are repurposed to indicate the alignment whereby a single 240-bit RLP frame is composed of 4 pseudo-V.110 frames in switching transport. (TS 48.020 section 15.1.) In the case of TCH/F9.6, setting both E2 and E3 is easy because all 4 pseudo-V.110 frames go out in the same clearmode RTP packet as a result of a single channel decoding operation. However, in the case of TCH/F4.8 there are two separate channel decoding operations producing two separate RTP packets 20 ms apart. Furthermore, GSM 05.03 section 3.4.1 specifies which TDMA frame positions hold which half of the RLP frame - therefore, the correct emission of bit E2 needs to be based on the TDMA frame number at which the block was received.

A similar situation occurs with TCH/H4.8 NT: we receive a single block from the 05.03 decoder every 40 ms, containing a full RLP frame, but we emit it as two separate RTP packets, each carrying 20 ms worth of bits. These RTP packets also require correct setting of E2 bit.

Related: OS#6579 Change-Id: I485af5e01ea87c1721a298a486cd344a17884200 --- M include/osmo-bts/csd_v110.h M src/common/csd_v110.c M src/common/l1sap.c M tests/csd/csd_test.c 4 files changed, 30 insertions(+), 10 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/54/38554/4