Re: [fluid-dev] SF2.01 section 8.1.3 # 37

[David Henningsson]

On 04/04/2013 10:34 AM, *simple* wrote:
> Hi,
> In fluid 1.1.6, fluid_voice.c, line 1010,
>    case GEN_VOLENVDECAY:               /* SF2.01 section 8.1.3 # 36 */
>    case GEN_VOLENVSUSTAIN:             /* SF2.01 section 8.1.3 # 37 */
>    case GEN_KEYTOVOLENVDECAY:          /* SF2.01 section 8.1.3 # 40 */
>      y = 1.0f - 0.001f * _GEN(voice, GEN_VOLENVSUSTAIN);
>      fluid_clip(y, 0.0f, 1.0f);
>      count = calculate_hold_decay_buffers(voice, GEN_VOLENVDECAY,
> GEN_KEYTOVOLENVDECAY, 1); /* 1 for decay */
>      fluid_voice_update_volenv(voice, FLUID_VOICE_ENVDECAY,
>                              count, 1.0f, count ? -1.0f / count : 0.0f,
> y, 2.0f);
>      break;
>  From the souce code, the sustain level is directly read out from GEN as
> a float cofficient. But according to the SF2.01 spec section 8.1.3, the
> value stored in GEN#37 is in unit of centibels.
> Could anyone please check if this is a bug here, or my
> mis-understanding? Thanks

Hi,

I've never studied this code in detail, but from fluid_rvoice_calc_amp 
(in fluid_rvoice.c) it looks like the entire envelope is in centibels. 
Thus it's probably correct as it is.

    target_amp = fluid_atten2amp (voice->dsp.attenuation)
      * fluid_cb2amp (960.0f * (1.0f - 
fluid_adsr_env_get_val(&voice->envlfo.volenv))
		      + fluid_lfo_get_val(&voice->envlfo.modlfo) * 
-voice->envlfo.modlfo_to_vol);

// David