Energy misalignment with frames for MDCT-stereo @80kbps

Basic info

• Float reference:
  • Decoder (float):05f58f72
• Fixed point:
  • Encoder (fixed):12778592

Bug description

There is a strange artifact for frames, 108-109 where there is an energy burst at the IGF region, but the energy for all remaining frequencies is very low. See plots:

Original:

Float:

BASOP:

Spectrum of BASOP (red) vs float (green)

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-1183\dp03a4s04_32.wav

./IVAS_cod -stereo -max_band SWB 80000 32 dp03a4s04_32.wav bit.192 ./IVAS_dec stereo 32 bit.192 out.wav

I have found another case with the same issue, item ap03s0305_32.wav frame 167 - can be found in the same box folder.

Float:

BASOP:

to reproduce:

./IVAS_cod -stereo -max_band SWB 96000 32 ap03s0305_32.wav bit.192 ./IVAS_dec stereo 32 bit.192 out.wav