Startup diff in IVAS_rend for MASA 1TC to 5.1 output

Basic info

• Float reference:
  • Renderer (float): 6cf0e3e8 (ivas-float-update)
• Fixed point:
  • Renderer (fixed): f5aed6ae (main)

Bug description

There is a bit peculiar difference visible in spectrogram with at least this specific recording. Probably can be present in other cases as well. This also seems to happen only with IVAS_rend and not IVAS_dec. In practice, there seems to be something missing in the BASOP version that is present in float.

This effect seems to disappear if (CLDFB) decorrelator is disabled (tested due to debugging another issue).

Looking at the code, there are updates made to IVAS_dec version of rendering in ivas_dirac_dec_render_sf_fx that are not part of the reduced version ivas_masa_ext_dirac_render_sf_fx done for MASA rendering in IVAS_rend. This might be already enough to explain the differences.

See below for spectrogram:

Another pic showing first channel amplitude plot. This shows some form of fade in present in BASOP which is not in float.

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-2044

Use the below command with the provided sample

./IVAS_rend -if MASA1 -i issue_test_sig.pcm -im issue_test_sig.met -fs 48 -of 5_1 -o rend_51.wav