severe artifacts with DTX in SBA

In SBA with DTX, large portions of a specific test item are probably misclassified as background noise. The scene comprises a helicopter flying by. Unfortunately, the sound file can not be published. In the inactive portions, there is also an additional chirp-like noise. The commit tested is aa0d22.

The command line is

./IVAS_cod -sba 3 -dtx -max_band fb 48000 48 input.pcm bit
./IVAS_dec BINAURAL 48 bit dec.wav