Stereo downmix EVS - Bad mode selection based on ITD.

Basic info

• Float reference: deee9b97
• Fixed point: e9c74df8

Bug description

There is an ITD mismatch between fixed and floating-point codes of stereo downmix, which results in ‘wrong’ decision between POC and PHA modes.

This issue is illustrated by an Orange file (voice_music.wav) already shared with NTT.

• ITD for floating-point (top) and for fixed-point (bottom) :
• Output signals for floating-point (top) and for fixed-point (bottom) :

Ways to reproduce

./IVAS_cod -stereo_dmx_evs 128000 48 voice_music.wav bit
./IVAS_dec 48 bit voice_music_128000_48-48.wav