Spectral distortion in multi-channel bitrate switching tests

Commit sha: 315a2539 Affected tests: Multi-channel bitrate switching tests. Following spectral plot is from the test case test_param_file_tests[Multi-channel 5_1 bitrate switching from 13.2 kbps to 512 kbps, 48kHz in, 48kHz out, 7_1_4 out]. Observations: The attached figure is a plot of the spectra of segment between 1s and 2s of the 5th channel of the floating point and the fixed plot outputs. About 5dB discrepancy is observed around 14kHz.

Encoder/decoder command lines:

./IVAS_cod_ref -q -mc 5_1 scripts/switchPaths/sw_mctech_5fr.bin 48 scripts/testv/stv51MC48c.wav tests/dut/param_file/enc/stv51MC48c.wav_Multi_channel_5_1_bitrate_switching_from_13_2_kbps_to_512_kbps_48kHz_in_48kHz_out_7_1_4_out.192
./IVAS_dec -q -fr 20 7_1_4 48 tests/dut/param_file/enc/stv51MC48c.wav_Multi_channel_5_1_bitrate_switching_from_13_2_kbps_to_512_kbps_48kHz_in_48kHz_out_7_1_4_out.192 tests/dut/param_file/dec/stv51MC48c.wav_Multi_channel_5_1_bitrate_switching_from_13_2_kbps_to_512_kbps_48kHz_in_48kHz_out_7_1_4_out.dec.wav`