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Bug #5570

open

coding: decode in-band data in AMR's special DTX frames (SID_FIRST, SID_UPDATE, SID_ONSET)

Added by fixeria 3 months ago. Updated 3 months ago.

Status:
New
Priority:
Normal
Assignee:
Category:
libosmocoding
Target version:
-
Start date:
05/21/2022
Due date:
% Done:

0%

Spec Reference:

Description

Whenever gsm0503_tch_a[fh]s_decode_dtx() detects a special AMR's DTX frame (e.g SID_FIRST, SID_UPDATE, SID_ONSET) it immediately jumps out and ignores the coded in-band data (CMI, CMC/CMR). A hard-coded default value=0 is assigned instead of the actual value(s) indicated by the MS. This basically breaks rate adaptation when DTXu is employed.


Related issues

Related to OsmoBTS - Bug #4984: AMR Rate Adaptation uses BER instead of C/I thresholdsStalledfixeria01/28/2021

Actions
Actions #1

Updated by fixeria 3 months ago

  • Related to Bug #4984: AMR Rate Adaptation uses BER instead of C/I thresholds added
Actions #2

Updated by fixeria 3 months ago

I submitted a few patches improving the current state of affairs and implementing CMI/CMC/CMR parsing for some DTX frame types:

https://gerrit.osmocom.org/c/libosmocore/+/28175 coding: do not reset codec ID on receipt of DTX frames [NEW]
https://gerrit.osmocom.org/c/libosmocore/+/28176 coding: add gsm0503_detect_a[fh]s_dtx_frame2() [NEW]
https://gerrit.osmocom.org/c/libosmocore/+/28177 coding: separate gsm0503_tch_a[fh]s_decode_inband()

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