Skip to content

Missing parameter update in speech/music classifier

The parameter lowrate_pitchGain which is part of the speech / music classifier handle st_fx->hSpMusClas is not updated in IVAS ACELP core, GC coder type.

In FLP, there is in the function encod_gen_voic() the following code:

    /* update long-term pitch gain for speech/music classifier */
    st->hSpMusClas->lowrate_pitchGain = 0.9f * st->hSpMusClas->lowrate_pitchGain + 0.1f * gain_pit;

In BASOP, there is in the EVS function encod_gen_voic_fx() the following counterpart.

    /*st_fx->lowrate_pitchGain = 0.9f * st_fx->lowrate_pitchGain + 0.1f * gain_pit_fx;*/
    hSpMusClas->lowrate_pitchGain = round_fx_sat( L_mac_sat( L_mult( 29491, hSpMusClas->lowrate_pitchGain ), 6554, gain_pit_fx ) ); /*Q14*Q16(0.1) + Q15 -> Q15*/

However, this code is missing in the IVAS function encod_gen_voic_ivas_fx().

Note: I observed this issue when working on !2685 (merged), see https://forge.3gpp.org/rep/sa4/audio/ivas-basop/-/blob/basop-2304-remove-duplicated-code-in-core-encoder-acelp-excitation-coding/lib_enc/enc_gen_voic_fx.c#L688.

Another observation is that this parameter is not updated consistently: different operations are used at different places, namely:

hSpMusClas->lowrate_pitchGain = mac_r_sat( L_mult( 29491, hSpMusClas->lowrate_pitchGain ), 3277, gain_pit ); /* Q14*Q16(0.1) + Q15 -> Q15  Q14*Q15 + Q14 -> Q14 lowrate_pitchGain is compared to Q14 in sp_music_classif */
hSpMusClas->lowrate_pitchGain = round_fx_sat( L_mac_sat( L_mult( 29491, hSpMusClas->lowrate_pitchGain ), 6554, gain_pit ) ); /*Q14*Q16(0.1) + Q15 -> Q15*/
#ifdef FIX_2254_IMPROV_PRECISION_OR_COMPLEXITY_NON_BE
        st->hSpMusClas->lowrate_pitchGain = mac_r( L_mult( 29491, st->hSpMusClas->lowrate_pitchGain ), 3277 /*Q15*/, gain_pit ); // Q14
#else
        st->hSpMusClas->lowrate_pitchGain = add( mult( 29491, st->hSpMusClas->lowrate_pitchGain ), mult( 3277 /*Q15*/, gain_pit ) ); // Q14
#endif

I am tagging here @vaillancour as the author of FIX_2254_IMPROV_PRECISION_OR_COMPLEXITY_NON_BE for a possible comment.

Edited by vaclav