JBM: ISM2, 48 kbit/s: Noise bursts, too high background noise level compared to Float

Basic info

• Fixed point:
  • Encoder (fixed): n/a
  • Decoder (fixed): Branch 20250826_branch_release_characterization_testing_main, rev. 7d39c224

Bug description

When decoding the ISM2, 48 kbit/s bitstream with JBM, there are various noise bursts and noise-level during active speech audible in BASOP, which is not the case in float.

BASOP:

Float:

First prominent occurrence is in frame no. 2681.

Ways to reproduce

Box folder: ...\_EXTERNAL_IVAS_CHAR_MC\issues\basop-issue-1998 (the folder contains also the bitstreams without any errors)

IVAS_dec -no_delay_cmp -voip -q BINAURAL 48 cat6_concatenated.ivas_processed.192 out.wav