LTV tests: High MLD Noise Burst for BASOP Decoder for OMASA 2TC4ISM Ambisonics output

Basic info

• Float reference:
  • Encoder (float): fdcce24c1c
  • Decoder (float): fdcce24c1c
• Fixed point:
  • Decoder (fixed): d2ae3897

Bug description

The testcase test_param_file.py::test_param_file_tests[ltv-OMASA 2TC 4ISM at br sw techs 13.2 to 512 kbps start 80 kbps, 48kHz in, 48kHz out, HOA3 out] reports a high MLD of 37.264320 in the LTV decoder test report.

Inspecting the output a bit further, the high MLD appears for channel 1 (Y), and this does not show up for STEREO, 7_1_4, BINAURAL or EXT output indicating a problem exclusively for ambisonics output.

This is easiest to see when the output is switched to FOA (noise burst near sample ~6500):

Float Reference:

BASOP:

Ways to reproduce

python3 -m pytest "tests/codec_be_on_mr_nonselection/test_param_file.py::test_param_file_tests[ltv-OMASA 2TC 4ISM at br sw techs 13.2 to 512 kbps start 80 kbps, 48kHz in, 48kHz out, HOA3 out]" --use_ltv --param_file scripts/config/self_test_ltv.prm --update_ref 2

# or decode the attached cut bitstream
# ./scripts/cut_bs.py --frame 5080 --length 50 ...
./IVAS_dec_ref FOA 48 cut.bs tmp_ref.wav
./IVAS_dec FOA 48 cut.bs tmp_cut.wav

cut.bs.zip