playmidi.c

SDL_mixer 是一个基于 SDL 的混音器

		  break;
		case 3: /* stage */
		  voice[w].velocity = voice[v].velocity;
		  break;
		case 4: /* plate */
		  voice[w].panning = voice[v].panning;
		  break;
		case 16: /* white room */
		  voice[w].echo_delay = 0;
		  break;
		case 17: /* tunnel */
		  voice[w].echo_delay *= 2;
		  voice[w].velocity /= 2;
		  break;
		case 18: /* canyon */
		  voice[w].echo_delay *= 2;
		  break;
		case 19: /* basement */
		  voice[w].velocity /= 2;
		  break;
	        default: break;
	    }
	}
  }
  played_note = voice[w].sample->note_to_use;
  if (!played_note) {
	played_note = e->a & 0x7f;
	if (variationbank == 35) played_note += 12;
	else if (variationbank == 36) played_note -= 12;
	else if (variationbank == 37) played_note += 7;
	else if (variationbank == 36) played_note -= 7;
  }
#if 0
  played_note = ( (played_note - voice[w].sample->freq_center) * voice[w].sample->freq_scale ) / 1024 +
		voice[w].sample->freq_center;
#endif
  voice[w].note = played_note;
  voice[w].orig_frequency = freq_table[played_note];

  if (chorus) {
	if (opt_stereo_surround) {
	  if (voice[v].panning < 64) voice[w].panning = voice[v].panning + 32;
	  else voice[w].panning = voice[v].panning - 32;
	}

	if (!voice[w].vibrato_control_ratio) {
		voice[w].vibrato_control_ratio = 100;
		voice[w].vibrato_depth = 6;
		voice[w].vibrato_sweep = 74;
	}
	voice[w].volume *= 0.40;
	voice[v].volume = voice[w].volume;
	recompute_amp(v);
        apply_envelope_to_amp(v);
	voice[w].vibrato_sweep = chorus/2;
	voice[w].vibrato_depth /= 2;
	if (!voice[w].vibrato_depth) voice[w].vibrato_depth = 2;
	voice[w].vibrato_control_ratio /= 2;
	voice[w].echo_delay += 30 * milli;

	if (XG_System_chorus_type >= 0) {
	    int subtype = XG_System_chorus_type & 0x07;
	    int chtype = 0x0f & (XG_System_chorus_type >> 3);
	    switch (chtype) {
		case 0: /* no effect */
		  break;
		case 1: /* chorus */
		  chorus /= 3;
		  if(channel[ voice[w].channel ].pitchbend + chorus < 0x2000)
            		voice[w].orig_frequency =
				(uint32)( (FLOAT_T)voice[w].orig_frequency * bend_fine[chorus] );
        	  else voice[w].orig_frequency =
			(uint32)( (FLOAT_T)voice[w].orig_frequency / bend_fine[chorus] );
		  if (subtype) voice[w].vibrato_depth *= 2;
		  break;
		case 2: /* celeste */
		  voice[w].orig_frequency += (voice[w].orig_frequency/128) * chorus;
		  break;
		case 3: /* flanger */
		  voice[w].vibrato_control_ratio = 10;
		  voice[w].vibrato_depth = 100;
		  voice[w].vibrato_sweep = 8;
		  voice[w].echo_delay += 200 * milli;
		  break;
		case 4: /* symphonic : cf Children of the Night /128 bad, /1024 ok */
		  voice[w].orig_frequency += (voice[w].orig_frequency/512) * chorus;
		  voice[v].orig_frequency -= (voice[v].orig_frequency/512) * chorus;
		  recompute_freq(v);
		  break;
		case 8: /* phaser */
		  break;
	      default:
		  break;
	    }
	}
	else {
	    chorus /= 3;
	    if(channel[ voice[w].channel ].pitchbend + chorus < 0x2000)
          	voice[w].orig_frequency =
			(uint32)( (FLOAT_T)voice[w].orig_frequency * bend_fine[chorus] );
            else voice[w].orig_frequency =
		(uint32)( (FLOAT_T)voice[w].orig_frequency / bend_fine[chorus] );
	}
  }
#if 0
  voice[w].loop_start = voice[w].sample->loop_start;
  voice[w].loop_end = voice[w].sample->loop_end;
#endif
  voice[w].echo_delay_count = voice[w].echo_delay;
  if (reverb) voice[w].echo_delay *= 2;

  recompute_freq(w);
  recompute_amp(w);
  if (voice[w].sample->modes & MODES_ENVELOPE)
    {
      /* Ramp up from 0 */
      voice[w].envelope_stage=ATTACK;
      voice[w].modulation_stage=ATTACK;
      voice[w].envelope_volume=0;
      voice[w].modulation_volume=0;
      voice[w].control_counter=0;
      voice[w].modulation_counter=0;
      recompute_envelope(w);
      /*recompute_modulation(w);*/
    }
  else
    {
      voice[w].envelope_increment=0;
      voice[w].modulation_increment=0;
    }
  apply_envelope_to_amp(w);
}


static void xremap(int *banknumpt, int *this_notept, int this_kit) {
	int i, newmap;
	int banknum = *banknumpt;
	int this_note = *this_notept;
	int newbank, newnote;

	if (!this_kit) {
		if (banknum == SFXBANK && tonebank[SFXBANK]) return;
		if (banknum == SFXBANK && tonebank[120]) *banknumpt = 120;
		return;
	}

	if (this_kit != 127 && this_kit != 126) return;

	for (i = 0; i < XMAPMAX; i++) {
		newmap = xmap[i][0];
		if (!newmap) return;
		if (this_kit == 127 && newmap != XGDRUM) continue;
		if (this_kit == 126 && newmap != SFXDRUM1) continue;
		if (xmap[i][1] != banknum) continue;
		if (xmap[i][3] != this_note) continue;
		newbank = xmap[i][2];
		newnote = xmap[i][4];
		if (newbank == banknum && newnote == this_note) return;
		if (!drumset[newbank]) return;
		if (!drumset[newbank]->tone[newnote].layer) return;
		if (drumset[newbank]->tone[newnote].layer == MAGIC_LOAD_INSTRUMENT) return;
		*banknumpt = newbank;
		*this_notept = newnote;
		return;
	}
}


static void start_note(MidiEvent *e, int i)
{
  InstrumentLayer *lp;
  Instrument *ip;
  int j, banknum, ch=e->channel;
  int played_note, drumpan=NO_PANNING;
  int32 rt;
  int attacktime, releasetime, decaytime, variationbank;
  int brightness = channel[ch].brightness;
  int harmoniccontent = channel[ch].harmoniccontent;
  int this_note = e->a;
  int this_velocity = e->b;
  int drumsflag = channel[ch].kit;
  int this_prog = channel[ch].program;

  if (channel[ch].sfx) banknum=channel[ch].sfx;
  else banknum=channel[ch].bank;

  voice[i].velocity=this_velocity;

  if (XG_System_On) xremap(&banknum, &this_note, drumsflag);
  /*   if (current_config_pc42b) pcmap(&banknum, &this_note, &this_prog, &drumsflag); */

  if (drumsflag)
    {
      if (!(lp=drumset[banknum]->tone[this_note].layer))
	{
	  if (!(lp=drumset[0]->tone[this_note].layer))
	    return; /* No instrument? Then we can't play. */
	}
      ip = lp->instrument;
      if (ip->type == INST_GUS && ip->samples != 1)
	{
	  ctl->cmsg(CMSG_WARNING, VERB_VERBOSE, 
	       "Strange: percussion instrument with %d samples!", ip->samples);
	}

      if (ip->sample->note_to_use) /* Do we have a fixed pitch? */
	{
	  voice[i].orig_frequency=freq_table[(int)(ip->sample->note_to_use)];
	  drumpan=drumpanpot[ch][(int)ip->sample->note_to_use];
	}
      else
	voice[i].orig_frequency=freq_table[this_note & 0x7F];

    }
  else
    {
      if (channel[ch].program==SPECIAL_PROGRAM)
	lp=default_instrument;
      else if (!(lp=tonebank[channel[ch].bank]->
		 tone[channel[ch].program].layer))
	{
	  if (!(lp=tonebank[0]->tone[this_prog].layer))
	    return; /* No instrument? Then we can't play. */
	}
      ip = lp->instrument;
      if (ip->sample->note_to_use) /* Fixed-pitch instrument? */
	voice[i].orig_frequency=freq_table[(int)(ip->sample->note_to_use)];
      else
	voice[i].orig_frequency=freq_table[this_note & 0x7F];
    }

    select_stereo_samples(i, lp);

  voice[i].starttime = e->time;
  played_note = voice[i].sample->note_to_use;

  if (!played_note || !drumsflag) played_note = this_note & 0x7f;
#if 0
  played_note = ( (played_note - voice[i].sample->freq_center) * voice[i].sample->freq_scale ) / 1024 +
		voice[i].sample->freq_center;
#endif
  voice[i].status=VOICE_ON;
  voice[i].channel=ch;
  voice[i].note=played_note;
  voice[i].velocity=this_velocity;
  voice[i].sample_offset=0;
  voice[i].sample_increment=0; /* make sure it isn't negative */

  voice[i].tremolo_phase=0;
  voice[i].tremolo_phase_increment=voice[i].sample->tremolo_phase_increment;
  voice[i].tremolo_sweep=voice[i].sample->tremolo_sweep_increment;
  voice[i].tremolo_sweep_position=0;

  voice[i].vibrato_sweep=voice[i].sample->vibrato_sweep_increment;
  voice[i].vibrato_sweep_position=0;
  voice[i].vibrato_depth=voice[i].sample->vibrato_depth;
  voice[i].vibrato_control_ratio=voice[i].sample->vibrato_control_ratio;
  voice[i].vibrato_control_counter=voice[i].vibrato_phase=0;
  voice[i].vibrato_delay = voice[i].sample->vibrato_delay;

  kill_others(i);

  for (j=0; j<VIBRATO_SAMPLE_INCREMENTS; j++)
    voice[i].vibrato_sample_increment[j]=0;


  attacktime = channel[ch].attacktime;
  releasetime = channel[ch].releasetime;
  decaytime = 64;
  variationbank = channel[ch].variationbank;

  switch (variationbank) {
	case  8:
		attacktime = 64+32;
		break;
	case 12:
		decaytime = 64-32;
		break;
	case 16:
		brightness = 64+16;
		break;
	case 17:
		brightness = 64+32;
		break;
	case 18:
		brightness = 64-16;
		break;
	case 19:
		brightness = 64-32;
		break;
	case 20:
		harmoniccontent = 64+16;
		break;
#if 0
	case 24:
		voice[i].modEnvToFilterFc=2.0;
      		voice[i].sample->cutoff_freq = 800;
		break;
	case 25:
		voice[i].modEnvToFilterFc=-2.0;
      		voice[i].sample->cutoff_freq = 800;
		break;
	case 27:
		voice[i].modLfoToFilterFc=2.0;
		voice[i].lfo_phase_increment=109;
		voice[i].lfo_sweep=122;
      		voice[i].sample->cutoff_freq = 800;
		break;
	case 28:
		voice[i].modLfoToFilterFc=-2.0;
		voice[i].lfo_phase_increment=109;
		voice[i].lfo_sweep=122;
      		voice[i].sample->cutoff_freq = 800;
		break;
#endif
	default:
		break;
  }


  for (j=ATTACK; j<MAXPOINT; j++)
    {
	voice[i].envelope_rate[j]=voice[i].sample->envelope_rate[j];
	voice[i].envelope_offset[j]=voice[i].sample->envelope_offset[j];
    }

  voice[i].echo_delay=voice[i].envelope_rate[DELAY];
  voice[i].echo_delay_count = voice[i].echo_delay;

  if (attacktime!=64)
    {
	rt = voice[i].envelope_rate[ATTACK];
	rt = rt + ( (64-attacktime)*rt ) / 100;
	if (rt > 1000) voice[i].envelope_rate[ATTACK] = rt;
    }
  if (releasetime!=64)
    {
	rt = voice[i].envelope_rate[RELEASE];
	rt = rt + ( (64-releasetime)*rt ) / 100;
	if (rt > 1000) voice[i].envelope_rate[RELEASE] = rt;
    }
  if (decaytime!=64)
    {
	rt = voice[i].envelope_rate[DECAY];
	rt = rt + ( (64-decaytime)*rt ) / 100;
	if (rt > 1000) voice[i].envelope_rate[DECAY] = rt;
    }

  if (channel[ch].panning != NO_PANNING)
    voice[i].panning=channel[ch].panning;
  else
    voice[i].panning=voice[i].sample->panning;
  if (drumpan != NO_PANNING)
    voice[i].panning=drumpan;

  if (variationbank == 1) {
    int pan = voice[i].panning;
    int disturb = 0;
    /* If they're close up (no reverb) and you are behind the pianist,
     * high notes come from the right, so we'll spread piano etc. notes
     * out horizontally according to their pitches.
     */
    if (this_prog < 21) {
	    int n = voice[i].velocity - 32;
	    if (n < 0) n = 0;
	    if (n > 64) n = 64;
	    pan = pan/2 + n;
	}
    /* For other types of instruments, the music sounds more alive if
     * notes come from slightly different directions.  However, instruments
     * do drift around in a sometimes disconcerting way, so the following
     * might not be such a good idea.
     */
    else disturb = (voice[i].velocity/32 % 8) +
	(voice[i].note % 8); /* /16? */

    if (pan < 64) pan += disturb;
    else pan -= disturb;
    if (pan < 0) pan = 0;
    else if (pan > 127) pan = 127;
    voice[i].panning = pan;
  }

  recompute_freq(i);
  recompute_amp(i);
  if (voice[i].sample->modes & MODES_ENVELOPE)
    {
      /* Ramp up from 0 */
      voice[i].envelope_stage=ATTACK;
      voice[i].envelope_volume=0;
      voice[i].control_counter=0;
      recompute_envelope(i);
    }
  else
    {
      voice[i].envelope_increment=0;
    }
  apply_envelope_to_amp(i);

  voice[i].clone_voice = -1;
  voice[i].clone_type = NOT_CLONE;

  clone_voice(ip, i, e, STEREO_CLONE, variationbank);
  clone_voice(ip, i, e, CHORUS_CLONE, variationbank);
  clone_voice(ip, i, e, REVERB_CLONE, variationbank);

  ctl->note(i);
}

static void kill_note(int i)
{
  voice[i].status=VOICE_DIE;
  if (voice[i].clone_voice >= 0)
	voice[ voice[i].clone_voice ].status=VOICE_DIE;
  ctl->note(i);
}


/* Only one instance of a note can be playing on a single channel. */
static void note_on(MidiEvent *e)
{
  int i=voices, lowest=-1; 
  int32 lv=0x7FFFFFFF, v;

  while (i--)
    {
      if (voice[i].status == VOICE_FREE)
	lowest=i; /* Can't get a lower volume than silence */
      else if (voice[i].channel==e->channel && 
	       (voice[i].note==e->a || channel[voice[i].channel].mono))
	kill_note(i);
    }

  if (lowest != -1)
    {
      /* Found a free voice. */
      start_note(e,lowest);
      return;
    }
  
#if 0
  /* Look for the decaying note with the lowest volume */
  i=voices;
  while (i--)
    {
      if (voice[i].status & ~(VOICE_ON | VOICE_DIE | VOICE_FREE))
	{
	  v=voice[i].left_mix;
	  if ((voice[i].panned==PANNED_MYSTERY) && (voice[i].right_mix>v))
	    v=voice[i].right_mix;
	  if (v<lv)
	    {
	      lv=v;
	      lowest=i;
	    }
	}
    }
#endif

  /* Look for the decaying note with the lowest volume */
  if (lowest==-1)
   {
   i=voices;
   while (i--)
    {
      if ( (voice[i].status & ~(VOICE_ON | VOICE_DIE | VOICE_FREE)) &&
	  (!voice[i].clone_type))
	{
	  v=voice[i].left_mix;
	  if ((voice[i].panned==PANNED_MYSTERY) && (voice[i].right_mix>v))
	    v=voice[i].right_mix;
	  if (v<lv)
	    {
	      lv=v;
	      lowest=i;
	    }
	}
    }
   }

  if (lowest != -1)
    {
      int cl = voice[lowest].clone_voice;

      /* This can still cause a click, but if we had a free voice to
	 spare for ramping down this note, we wouldn't need to kill it
	 in the first place... Still, this needs to be fixed. Perhaps
	 we could use a reserve of voices to play dying notes only. */

      if (cl >= 0) {
	if (voice[cl].clone_type==STEREO_CLONE ||
		       	(!voice[cl].clone_type && voice[lowest].clone_type==STEREO_CLONE))
	   voice[cl].status=VOICE_FREE;
	else if (voice[cl].clone_voice==lowest) voice[cl].clone_voice=-1;
      }

      cut_notes++;
      voice[lowest].status=VOICE_FREE;
      ctl->note(lowest);
      start_note(e,lowest);
    }
  else
    lost_notes++;
}

static void finish_note(int i)
{
  if (voice[i].sample->modes & MODES_ENVELOPE)
    {
      /* We need to get the envelope out of Sustain stage */
      voice[i].envelope_stage=3;
      voice[i].status=VOICE_OFF;
      recompute_envelope(i);
      apply_envelope_to_amp(i);
      ctl->note(i);
    }
  else
    {
      /* Set status to OFF so resample_voice() will let this voice out
         of its loop, if any. In any case, this voice dies when it
         hits the end of its data (ofs>=data_length). */
      voice[i].status=VOICE_OFF;
    }

  { int v;
    if ( (v=voice[i].clone_voice) >= 0)
      {
	voice[i].clone_voice = -1;
        finish_note(v);
      }
  }
}

static void note_off(MidiEvent *e)
{
  int i=voices, v;
  while (i--)
    if (voice[i].status==VOICE_ON &&
	voice[i].channel==e->channel &&
	voice[i].note==e->a)
      {
	if (channel[e->channel].sustain)
	  {
	    voice[i].status=VOICE_SUSTAINED;

    	    if ( (v=voice[i].clone_voice) >= 0)
	      {
		if (voice[v].status == VOICE_ON)
		  voice[v].status=VOICE_SUSTAINED;
	      }

	    ctl->note(i);
	  }
	else
	  finish_note(i);
	return;
      }
}

/* Process the All Notes Off event */
static void all_notes_off(int c)
{
  int i=voices;
  ctl->cmsg(CMSG_INFO, VERB_DEBUG, "All notes off on channel %d", c);
  while (i--)
    if (voice[i].status==VOICE_ON &&
	voice[i].channel==c)
      {
	if (channel[c].sustain) 
	  {
	    voice[i].status=VOICE_SUSTAINED;
	    ctl->note(i);
	  }
	else
	  finish_note(i);
      }
}

/* Process the All Sounds Off event */
static void all_sounds_off(int c)
{
  int i=voices;
  while (i--)
    if (voice[i].channel==c && 
	voice[i].status != VOICE_FREE &&
	voice[i].status != VOICE_DIE)
      {
	kill_note(i);
      }
}

static void adjust_pressure(MidiEvent *e)
{
  int i=voices;
  while (i--)
    if (voice[i].status==VOICE_ON &&
	voice[i].channel==e->channel &&
	voice[i].note==e->a)
      {