SBA DTX: weird comfort noise shape and possible transition issue

Basic info

• Commit SHA: 3d8045a9

Bug description

Discovered in the course of sa4/audio/ivas-basop#1084. DTX for SBA FOA input produces a gap in the comfort noise at about 8kHz and shows a transition issue in one channel. When rendering to binaural for listening, the transition gap does not seem to be really audible, but the gap in the comfort noise produces a quite annoying repetitive hissing sound.

Ways to reproduce

Test vector can be found on Box for BASOP issue 1084.

./IVAS_cod -dtx -sba 1 24400 48 dm4aa1s04_HOA1_48_-16.wav bit
./IVAS_dec fia 48 bit out.wav