While running encoder conformance tests using Cadence tools, we observed that the reference decoder enters int an infinite loop for 3 test cases. In these cases, the bitstreams were generated using an encoder binary built with Cadence tools. The encoder binary was compiled with the -O0 option, which disables all optimizations (so only deviation would be the math kernels as they come from optimized math libraries). We did not observe any issues during the encoding phase; however, a hang occurs during the decoding stage with the reference decoder binary. The reference decoder binary was also built with the -O0 option using the standard Clang 18.1.6 compiler. This issues The following decoder commands can be used to reproduce the issue: 1. Inifite loop after 191 frames : [stv1MASA2TC48n.wav_MASA_1dir_2TC_at_128_kbps_48kHz_in_48kHz_out_DTX_on_EXT_out.192](/uploads/911ebc1e5fdeecbb6371e2f29ab2975d/stv1MASA2TC48n.wav_MASA_1dir_2TC_at_128_kbps_48kHz_in_48kHz_out_DTX_on_EXT_out.192) ``` ./IVAS_dec -fr 20 EXT 48 stv1MASA2TC48n.wav_MASA_1dir_2TC_at_128_kbps_48kHz_in_48kHz_out_DTX_on_EXT_out.192 stv1MASA2TC48n.wav_MASA_1dir_2TC_at_128_kbps_48kHz_in_48kHz_out_DTX_on_EXT_out_DEC.wav ``` 2. Inifite loop after 191 frames [stv20sOMASA_2ISM2TC.wav_OMASA_vdir2TC_2ISM_at_256_kbps_48kHz_in_32kHz_out_BINAURAL_ROOM_IR_out.192](/uploads/c4e64ac16ae811504c2894fb52ce0d3b/stv20sOMASA_2ISM2TC.wav_OMASA_vdir2TC_2ISM_at_256_kbps_48kHz_in_32kHz_out_BINAURAL_ROOM_IR_out.192) ``` ./IVAS_dec -fr 20 BINAURAL_ROOM_IR 32 stv20sOMASA_2ISM2TC.wav_OMASA_vdir2TC_2ISM_at_256_kbps_48kHz_in_32kHz_out_BINAURAL_ROOM_IR_out.192 stv20sOMASA_2ISM2TC.wav_OMASA_vdir2TC_2ISM_at_256_kbps_48kHz_in_32kHz_out_BINAURAL_ROOM_IR_out_DEC.wav ``` 3. Inifite loop after 703 frames [stv20sOMASA_4ISM1TC.wav_OMASA_vdir1TC_4ISM_at_br_sw_techs_13_2_to_512_kbps_start_32_kbps_48kHz_in_48kHz_out_BINAURAL_out_FER_at_5_.192](/uploads/cdf7fafde6d165ff7dfdad26de3e6bf1/stv20sOMASA_4ISM1TC.wav_OMASA_vdir1TC_4ISM_at_br_sw_techs_13_2_to_512_kbps_start_32_kbps_48kHz_in_48kHz_out_BINAURAL_out_FER_at_5_.192) ``` ./IVAS_dec -fr 20 BINAURAL 48 stv20sOMASA_4ISM1TC.wav_OMASA_vdir1TC_4ISM_at_br_sw_techs_13_2_to_512_kbps_start_32_kbps_48kHz_in_48kHz_out_BINAURAL_out_FER_at_5_.192 stv20sOMASA_4ISM1TC.wav_OMASA_vdir1TC_4ISM_at_br_sw_techs_13_2_to_512_kbps_start_32_kbps_48kHz_in_48kHz_out_BINAURAL_out_FER_at_5__DEC.wav ``` Our quick analysis indicated the program counter is stuck in following loop from lib_dec/ivas_masa_dec.c (line 1999) ``` while ( index >= 0 ) { if ( valid_ratio_index( j, K, nchan_ism - 1 ) ) { index--; } j++; } ```