High MLD issue for Multi-channel 7_1_4 bitrate switching from 13.2 kbps to 512 kbps, 48kHz in, 48kHz out, HOA3 out

Basic info

• Encoder (fixed): 2950fee8
• Decoder (float): b41d89f8

Bug description

For High MLD issue - Orig - Multi-channel 7_1_4 bitrate switching from 13.2 kbps to 512 kbps, 48kHz in, 48kHz out, HOA3 out, MLD is observed to be ~26.

MLD of 26 is contributed by 2nd channel.

Waveform comparison:

In the above picture, 1st (float encoder + float decoder) and 2nd (Fixed encoder + float decoder)

So, the spike observed at interval of 2.10 sec, is causing the high MLD.

From the image, it can be observed that spike is present when stream is encoded using float encoder and decoded with float decoder. But spike is not present in case for Fixed Encoder + Float decoder. 

When the fixed encoded- float decoded output is compared with original input file, it is observed that there is no spike.

Commands:

IVAS_cod -mc 7_1_4 ../scripts/switchPaths/sw_mctech_5fr.bin 48 testv/stv714MC48c.wav bit
IVAS_dec HOA3 48 bit testv/stv51MC48c.wav_sw_48-48_HOA3.tst

Also tried rendering to 7.1.4 instead of HOA3 using the below commands:

IVAS_cod -mc 7_1_4 ../scripts/switchPaths/sw_mctech_5fr.bin 48 testv/stv714MC48c.wav bit
IVAS_dec 7_1_4 48 bit testv/stv51MC48c.wav_sw_48-48_HOA3.wav

With these, 2nd channel can be compared directly with original input.

In the above image,

1^st: Original input wav. 2^nd channel

2^nd: Float Encoder + Float Decoder, 2^nd channel

3^rd: Fixed Encoder + Float decoder, 2^nd channel

Spike seems to be happening only in float point code.