Fixes for multiple sounds playing at once. (#235)

doc/ChangeLog.txt

@@ -603,6 +603,7 @@ FIXED: Fixed graphical glitches with an opening gate:
 	2. with the top half of a big pillar above-right.
 FIXED: Validate mode crashed with the error "init_scaling: SDL_CreateTexture: Invalid renderer".
 DONE: First implementation of multiple sounds playing at once. (#235)
-	Problems:
-	* The screaming of the prince doesn't stop when he lands.
-	* The level door sliding pops badly. It is erroneously played in multiple copies at the same time, causing the sample values to overflow.
+	This revealed the following cases when the game relies on sounds interrupting each other:
+	FIXED: The screaming of the prince doesn't stop when he lands.
+	FIXED: The level door sliding pops badly. It is erroneously played in multiple copies at the same time, causing the sample values to overflow.
+	FIXED: The level door sliding doesn't stop when the door slams.

src/midi.c

@@ -517,7 +517,8 @@ void midi_callback(void *userdata, Uint8 *stream, int len) {
 			OPL3_GenerateStream(&opl_chip, temp_buffer, advance_frames);
 			if (is_sound_on && enable_music) {
 				for (int sample = 0; sample < advance_frames * 2; ++sample) {
-					((short*)stream)[sample] += temp_buffer[sample];
+					//((short*)stream)[sample] += temp_buffer[sample];
+					saturating_add_to_s16(&( ((short*)stream)[sample] ), temp_buffer[sample]);
 				}
 			}
 			free(temp_buffer);

src/proto.h

@@ -78,6 +78,8 @@ void show_splash();
 void check_quick_op();
 void restore_room_after_quick_load();
 #endif // USE_QUICKSAVE
+void stop_sound(int sound_id);
+bool is_sound_playing(int sound_id);
 
 // SEG001.C
 int __pascal far proc_cutscene_frame(int wait_frames);
@@ -635,6 +637,11 @@ void set_chtab_palette(chtab_type* chtab, byte* colors, int n_colors);
 int has_timer_stopped(int index);
 sound_buffer_type* load_sound(int index);
 void free_sound(sound_buffer_type far *buffer);
+void stop_digi_from_buffer(sound_buffer_type far *buffer);
+bool is_digi_playing_from_buffer(sound_buffer_type far *buffer);
+Sint16 saturating_add_s16(Sint16 left, Sint16 right);
+void saturating_add_to_s16(Sint16* left, Sint16 right);
+int check_sound_playing_except_digi();
 
 // SEQTABLE.C
 void apply_seqtbl_patches();

src/seg000.c

@@ -1564,6 +1564,15 @@ void fix_sound_priorities() {
 
 // seg000:12C5
 void __pascal far play_sound(int sound_id) {
+	// For digi sounds, use the new system which allows playing multiple sounds at once.
+	sound_buffer_type* sound = sound_pointers[sound_id];
+	if (sound != NULL && sound->type == sound_digi_converted) {
+		// Don't let the same sound play more than once (e.g. loose floors on level 11).
+		if (is_sound_playing(sound_id)) return;
+		play_sound_from_buffer(sound);
+		return;
+	}
+	// For other sounds, keep using the old system.
 	//printf("Would play sound %d\n", sound_id);
 	if (next_sound < 0 || sound_prio_table[sound_id] <= sound_prio_table[next_sound]) {
 		if (NULL == sound_pointers[sound_id]) return;
@@ -1576,20 +1585,24 @@ void __pascal far play_sound(int sound_id) {
 // seg000:1304
 void __pascal far play_next_sound() {
 	if (next_sound >= 0) {
-	/*
-		if (!check_sound_playing() ||
+		if (!check_sound_playing_except_digi() ||
 			(sound_interruptible[current_sound] != 0 && sound_prio_table[next_sound] <= sound_prio_table[current_sound])
 		) {
-	*/
 			current_sound = next_sound;
 			play_sound_from_buffer(sound_pointers[current_sound]);
-	/*
 		}
-	*/
 	}
 	next_sound = -1;
 }
 
+void stop_sound(int sound_id) {
+	stop_digi_from_buffer(sound_pointers[sound_id]);
+}
+
+bool is_sound_playing(int sound_id) {
+	return is_digi_playing_from_buffer(sound_pointers[sound_id]);
+}
+
 // seg000:1353
 void __pascal far check_sword_vs_sword() {
 	if (Kid.frame == 167 || Guard.frame == 167) {

src/seg003.c

@@ -104,8 +104,9 @@ void __pascal far play_level(int level_number) {
 		do_startpos();
 		have_sword = /*(level_number != 1)*/ (level_number == 0 || level_number >= custom->have_sword_from_level);
 		find_start_level_door();
+		stop_sounds();
 		// busy waiting?
-		while (check_sound_playing() && !do_paused()) idle();
+		while (check_sound_playing_except_digi() && !do_paused()) idle();
 		stop_sounds();
 		#ifdef USE_REPLAY
 		if (replaying) replay_restore_level();

src/seg005.c

@@ -113,6 +113,7 @@ void __pascal far do_fall() {
 // seg005:0090
 void __pascal far land() {
 	word seq_id;
+	stop_sound(sound_1_falling);
 	is_screaming = 0;
 	Char.y = y_land[Char.curr_row + 1];
 	if (get_tile_at_char() != tiles_2_spike) {

src/seg006.c

@@ -1107,6 +1107,7 @@ void __pascal far check_grab() {
 			play_seq();
 			grab_timer = 12;
 			play_sound(sound_9_grab); // grab
+			stop_sound(sound_1_falling);
 			is_screaming = 0;
 #ifdef FIX_CHOMPERS_NOT_STARTING
 			if (fixes->fix_chompers_not_starting) start_chompers();
@@ -1194,7 +1195,7 @@ void __pascal far play_kid() {
 			load_fram_det_col();
 			set_start_pos();
 		}
-		if (check_sound_playing() && current_sound != 5) { // gate opening
+		if (check_sound_playing_except_digi() && current_sound != 5) { // gate opening
 			return;
 		}
 		is_show_time = 0;

src/seg007.c

@@ -439,13 +439,16 @@ Possible values of trob_type:
 			if ((sbyte)curr_modifier < 0) {
 				curr_modifier = 0;
 				trob.type = -1;
+				stop_sound(sound_15_leveldoor_sliding);
 				play_sound(sound_14_leveldoor_closing); // level door closing
 			} else {
 				if (trob.type == 4 &&
 					(sound_flags & sfDigi)
 				) {
 					sound_interruptible[sound_15_leveldoor_sliding] = 1;
-					play_sound(sound_15_leveldoor_sliding); // level door sliding (closing)
+					if (!is_sound_playing(sound_15_leveldoor_sliding)) {
+						play_sound(sound_15_leveldoor_sliding); // level door sliding (closing)
+					}
 				}
 			}
 		} else {
@@ -454,9 +457,10 @@ Possible values of trob_type:
 			if (curr_modifier >= 43) {
 				trob.type = -1;
 #ifdef FIX_FEATHER_INTERRUPTED_BY_LEVELDOOR
-				if (!(fixes->fix_feather_interrupted_by_leveldoor && is_feather_fall))
+				//if (!(fixes->fix_feather_interrupted_by_leveldoor && is_feather_fall))
 #endif
-				stop_sounds();
+				//stop_sounds();
+				stop_sound(sound_15_leveldoor_sliding);
 				if (leveldoor_open == 0 || leveldoor_open == 2) {
 					leveldoor_open = 1;
 					if (current_level == /*4*/ custom->mirror_level) {
@@ -467,7 +471,9 @@ Possible values of trob_type:
 				}
 			} else {
 				sound_interruptible[sound_15_leveldoor_sliding] = 0;
-				play_sound(sound_15_leveldoor_sliding); // level door sliding (opening)
+				if (!is_sound_playing(sound_15_leveldoor_sliding)) {
+					play_sound(sound_15_leveldoor_sliding); // level door sliding (opening)
+				}
 			}
 		}
 	}

src/seg009.c

@@ -1893,8 +1893,20 @@ void __pascal far play_speaker_sound(sound_buffer_type far *buffer) {
 	SDL_PauseAudio(0);
 }
 
+// Sound samples should be mixed together like this to prevent popping.
+Sint16 saturating_add_s16(Sint16 left, Sint16 right) {
+	Sint32 result = (Sint32)left + (Sint32)right;
+	if (result < INT16_MIN) result = INT16_MIN;
+	if (result > INT16_MAX) result = INT16_MAX;
+	return result;
+}
+
+void saturating_add_to_s16(Sint16* left, Sint16 right) {
+	*left = saturating_add_s16(*left, right);
+}
+
 void digi_callback(void *userdata, Uint8 *stream, int len) {
-	printf("playing_digi_count = %d\n", playing_digi_count);
+	//printf("playing_digi_count = %d\n", playing_digi_count);
 	for (int digi_index = 0; digi_index < playing_digi_count; digi_index++) {
 		playing_digi_type* current_playing_digi = &playing_digis[digi_index];
 
@@ -1910,7 +1922,8 @@ void digi_callback(void *userdata, Uint8 *stream, int len) {
 			int copy_samples = copy_len / 2; // Assuming 16 bits per sample!
 			short* temp_buffer = (short*)current_playing_digi->digi_remaining_pos;
 			for (int sample = 0; sample < copy_samples; sample++) {
-				((short*)stream)[sample] += temp_buffer[sample];
+				//((short*)stream)[sample] += temp_buffer[sample];
+				saturating_add_to_s16(&( ((short*)stream)[sample] ), temp_buffer[sample]);
 			}
 		} else {
 			// If sound is off: Mute the sound but keep track of where we are.
@@ -1932,6 +1945,7 @@ void digi_callback(void *userdata, Uint8 *stream, int len) {
 	}
 
 	// Delete the ended sounds from the list.
+	// Inspired by process_trobs().
 	int dest_index = 0;
 	for (int source_index = 0; source_index < playing_digi_count; source_index++) {
 		if (playing_digis[source_index].digi_remaining_length > 0) {
@@ -2320,6 +2334,29 @@ void __pascal far play_digi_sound(sound_buffer_type far *buffer) {
 	SDL_PauseAudio(0);
 }
 
+void stop_digi_from_buffer(sound_buffer_type far *buffer) {
+	if (buffer->type != sound_digi_converted) return;
+	SDL_LockAudio();
+	byte* digi_buffer = (byte*) buffer->converted.samples;
+	for (int source_index = 0; source_index < playing_digi_count; source_index++) {
+		if (playing_digis[source_index].digi_buffer == digi_buffer) {
+			playing_digis[source_index].digi_remaining_length = 0;
+		}
+	}
+	SDL_UnlockAudio();
+}
+
+bool is_digi_playing_from_buffer(sound_buffer_type far *buffer) {
+	if (buffer->type != sound_digi_converted) return false;
+	byte* digi_buffer = (byte*) buffer->converted.samples;
+	for (int source_index = 0; source_index < playing_digi_count; source_index++) {
+		if (playing_digis[source_index].digi_buffer == digi_buffer) {
+			return true;
+		}
+	}
+	return false;
+}
+
 void free_sound(sound_buffer_type far *buffer) {
 	if (buffer == NULL) return;
     if (buffer->type == sound_ogg) {
@@ -2380,6 +2417,10 @@ int __pascal far check_sound_playing() {
 	return speaker_playing || digi_playing || midi_playing || ogg_playing;
 }
 
+int check_sound_playing_except_digi() {
+	return speaker_playing || midi_playing || ogg_playing;
+}
+
 void apply_aspect_ratio() {
 	// Allow us to use a consistent set of screen co-ordinates, even if the screen size changes
 	if (use_correct_aspect_ratio) {