Encoder: Too much energy in BWE in McMASA 7.1+4 at 32kbps -36LKFS processing

Basic info

• Float reference:
  • Encoder (float): RC02 executables
  • Decoder (float): RC02 executables
• Fixed point:
  • Encoder (fixed): RC02 executables
  • Decoder (fixed): RC02 executables

Bug description

The fixed point output for condition c28 in P.800-7 category 2 (7.1+4) has an audibly louder BWE, which sounds like comfort noise addition, compared to the floating point output for condition c19. This is subtle but audible and since the noise is not present at all in the reference/FL conditions, can result in worse perceptual quality.

• This issue seems only to be present for sample 01 (this is selected from -36LKFS processing for cat 2)
• This does not show up at -16 or -26LKFS
• c10 which uses the floating point encoder and fixed point decoder does not have this issue
• This does not occur at higher bitrates for fixed point

Float (c19)	Fixed (c28)

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-2020

Use the script reproduce.sh, or alternatively process using the uploaded modified experiment configuration with only c19 and c28 as conditions.