[regression] Encoder crash for MDCT Stereo at 80 kbps and above in stereo_mdct_core_enc_fx()

Basic info

• Float reference:
  • Encoder (float):
  • Decoder (float):
• Fixed point:
  • Encoder (fixed): d74de338
  • Decoder (fixed):

Bug description

The fixed point encoder crashes with an assert:

Assertion failed: (0), function L_sub, file basop32.c, line 1742.

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-1434

./IVAS_cod_fx -stereo -max_band FB 80000 48 dp03a4s04_48.-10dB.wav bit
# this crash also occurs for 96, 128, 160, 192 and 256 kbps