Audible glitch when stereo signal is decoded in mono

Basic info

• Commit SHA: 03f25119
• Platform: MSVC

Bug description

When a signal is encoded with stereo and decoded in mono, a glitch appears, at ~2.59s, when the element mode is going from TD to DFT. If the signal is decoded as a stereo signal, the glitch is not there.

Even if the switching from DFT to TD happens also at 32kbps, the issue is only present at 24.4kbps (Maybe the problem could be at 16.4 kbps too, but for this sample, there is no switching at 16.4kbps)

From top to bottom from float encoder and float decoder:

• Mono synthesis
• Left channel of the stereo synthesis
• Right channel of the stereo synthesis
• element mode

Ways to reproduce

input at :

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-1364

(Clear steps or refer to a failing automated test, e.g. with a pipeline link)

IVAS_cod -stereo 24400  48 ap01a1s03.wav bit.flt
IVAS_dec MONO 48 bit.flt C:\Temp\out.fltflt.wav