fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmocore/+/28122 ) Change subject: coding: properly handle AFS_SID_UPDATE frames in DTX mode ...................................................................... coding: properly handle AFS_SID_UPDATE frames in DTX mode There are two similar values in enum gsm0503_amr_dtx_frames: * AFS_SID_UPDATE - precursor of SID UPDATE, * AFS_SID_UPDATE_CN - the actual SID UPDATE. The former is internally used by libosmocoding to mark the current frame as a precursor of the actual SID UPDATE frame - the later. +---+---+---+---+---+---+---+---+ | _ | _ | _ | _ | a | b | c | d | AFS_SID_UPDATE +---+---+---+---+---+---+---+---+ | a | b | c | d | _ | _ | _ | _ | AFS_SID_UPDATE_CN +---+---+---+---+---+---+---+---+ This is required because function gsm0503_tch_afs_decode_dtx() is invoked by TDMA scheduler on every 4th received burst, while the burst buffer is 8 bursts wide. Currently, whenever gsm0503_detect_afs_dtx_frame() detects an AFS_SID_UPDATE frame, we still attempt to decode it as a speech or data below in gsm0503_tch_afs_decode_dtx(). This is indeed a bug, which results in unexpected BER values: * expected BER 0/212, * actual BER 252/448. We should return immediately once we have detected an AFS_SID_UPDATE. This patch fixes unexpected BER-SUB values during DTXu silence periods. Change-Id: I813081a4c0865958eee2496fe251ae17235ac842 Related: SYS#5853 --- M src/coding/gsm0503_coding.c 1 file changed, 1 insertion(+), 0 deletions(-) git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/22/28122/1 diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c index dae3a19..65141b2 100644 --- a/src/coding/gsm0503_coding.c +++ b/src/coding/gsm0503_coding.c @@ -2221,6 +2221,7 @@ tch_amr_reassemble(tch_data, conv, 39); len = 5; goto out; + case AFS_SID_UPDATE: case AFS_ONSET: len = 0; goto out; -- To view, visit https://gerrit.osmocom.org/c/libosmocore/+/28122 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: libosmocore Gerrit-Branch: master Gerrit-Change-Id: I813081a4c0865958eee2496fe251ae17235ac842 Gerrit-Change-Number: 28122 Gerrit-PatchSet: 1 Gerrit-Owner: fixeria <vyanitskiy(a)sysmocom.de> Gerrit-MessageType: newchange