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Spectral artifacts observed when HOA3 input is decoded into 7.1.4 format and rendered to BINAURAL format using IVAS renderer

Basic info

  • Float reference:
    • Encoder (float):
    • Decoder (float):
  • Fixed point:

Bug description

During the cross-check of items for the BS.1534-5 test, one item (am05a1s03) showed distinct spectral artifacts (regular peaks) in the frequency domain.

These artifacts appear only when the codec output is set to 7.1.4 format and then rendered to BINAURAL format. When the decoder is configured to produce BINAURAL output directly, the artifacts do not occur. This suggests that the issue may be in the IVAS renderer rather than in the IVAS decoder.

The artifacts were observed on both Windows and Linux platforms. However, because the spectral level in the affected section is low, the overall audio quality is not impacted.

The figure below illustrates the spectral artifacts:

  • am05a1s03.pre2.BINAURAL.wav represents the HOA3 input rendered to the BINAURAL format by IVAS_rend.
  • syn.BINAURAL.Linux represents the BINAURAL output produced directly by IVAS_dec.
  • syn.7_1_4.BINAURAL.Linux represents the 7.1.4 output produced by IVAS_dec and rendered to BINAURAL format by IVAS_rend.

image

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_CHAR_MC\Issues\basop-issue-2043

./IVAS_cod -sba 3 64000 48 am05a1s03.pre2.wav bit.Linux
./IVAS_dec 7_1_4 48 bit.Linux syn.7_1_4.Linux.wav
./IVAS_rend -i syn.7_1_4.Linux.wav -if 7_1_4 -o syn.7_1_4.BINAURAL.Linux.wav -of BINAURAL
Edited by Ghost User