High MLD and quality degradations for MCT-MC at 96kbps

Basic info

• Float reference:
  • Encoder (float): 5067d70d
  • Decoder (float): 5067d70d
• Fixed point:
  • Encoder (fixed): f5041511
  • Decoder (fixed):

Bug description

The fixed point encoded version of this input test vector has degraded quality and a high MLD of 17.9. Subjective listening to the fixed point version also shows that the quality is worse, especially in the last 2-3 seconds of the item.

Float reference:

Fixed point:

The following issues can be observed compared to the float reference:

• Several spectral holes
• Missing or reduced energy in the 5-8kHz region:
  • 
• Differing block length selection (see channel 3, around 1.65s):
  • Float:
  • Fixed:

Ways to reproduce

Input vector has been uploaded.

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-1275

./IVAS_cod_fx -mc 5_1 -max_band FB 96000 48 bm2aa1s13_48.wav bit
./IVAS_dec_flt_ref 5_1 48 bit out.wav