BASOP encoder: large differences in core channels cause large differences in DirAC parameters in OSBA @ 256 kbps

Basic info

• Float reference:
  • Encoder (float): 29105a8444c1807483dc01de25812c2ca1b38727
  • Decoder (float): 29105a8444c1807483dc01de25812c2ca1b38727
• Fixed point:
  • Encoder (fixed): d3fbdc6b

Bug description

For the 11 lower CLDFB bands, the DirAC parameters are estimated in the decoder. With the LTVs one can see very large differences in these parameters. These occur when the same signal is encoded with the BASOP and float encoders, these two bitstreams are decoded with the float decoder, and the DirAC parameters are written to a file in the float decoder. This is a secondary problem that comes from differences in the MCT channels and can be revisited once some progress has been made there.

Ways to reproduce

.[/ivas-float-update]/IVAS_cod -sba 3 256000 48 ../ivas-pc-testfiles/ltv48_HOA3.wav bit[_fl]
 ./ivas-float-update/IVAS_dec EXT 48 bit[_fl] dec[_fl].wav

The below patch for ivas-float-update writes the parameters to a file. The Jupyter notebook can be used to plot the differences.

0001-write-DirAC-parameters-to-text-files.patch

HO-DirAC-compare.ipynb