Rate switching MASA 2TC has high MLD caused by BASOP encoder on specific case

Basic info

• Float reference:
  • Encoder (float): db364042
  • Decoder (float): db364042
• Fixed point:
  • Encoder (fixed): f1458362
  • Decoder (fixed): f1458362

Bug description

Looking at this specific rate switching case of MASA 2TC, I am seeing surprisingly high MLD of 22 for the transport channels when BASOP encoder is used whereas the path (float enc -> BASOP dec) has MLD of 1.3. I do not see any evident reason for the diff in plots so this would require a bit of studying. There are some metadata coding differences which can of course affect the bit budget for core but I have seen worse metadata differences with still good MLD results. It might be that there are some core decision differences or the rate switching is somehow handled differently.

Ways to reproduce

Rate switching pattern here generic_start_128k_20frames.bin

IVAS_cod -masa 2 ltv48_MASA2TC.met -max_band swb generic_start_128k_20frames.bin 48 ltv48_MASA2TC.wav test_0070.bs
IVAS_dec EXT 48 test_0070.bs 0070_ltv48_MASA2TC.wav_generic_start_128k_20frames_48-48___EXT.wav