Update midi_synthesizer.py

midi_synthesizer.py

@@ -4,45 +4,50 @@ import numpy as np
 
 def synthesis(midi_opus, soundfont_path, sample_rate=44100):
     ticks_per_beat = midi_opus[0]
-    event_list = []
-    for track_idx, track in enumerate(midi_opus[1:]):
-        abs_t = 0
-        for event in track:
-            abs_t += event[1]
-            event_new = [*event]
-            event_new[1] = abs_t
-            event_list.append(event_new)
-    event_list = sorted(event_list, key=lambda e: e[1])
+    tempo = int((60 / 140) * 10 ** 6)  # default 140 bpm
 
-    tempo = int((60 / 120) * 10 ** 6)  # default 120 bpm
-    ss = np.empty((0, 2), dtype=np.int16)
     fl = fluidsynth.Synth(samplerate=float(sample_rate))
     sfid = fl.sfload(soundfont_path)
-    last_t = 0
-    for c in range(16):
-        fl.program_select(c, sfid, 128 if c == 9 else 0, 0)
-    for event in event_list:
-        name = event[0]
-        sample_len = int(((event[1] / ticks_per_beat) * tempo / (10 ** 6)) * sample_rate)
-        sample_len -= int(((last_t / ticks_per_beat) * tempo / (10 ** 6)) * sample_rate)
-        last_t = event[1]
-        if sample_len > 0:
-            sample = fl.get_samples(sample_len).reshape(sample_len, 2)
-            ss = np.concatenate([ss, sample])
-        if name == "set_tempo":
-            tempo = event[2]
-        elif name == "patch_change":
-            c, p = event[2:4]
-            fl.program_select(c, sfid, 128 if c == 9 else 0, p)
-        elif name == "control_change":
-            c, cc, v = event[2:5]
-            fl.cc(c, cc, v)
-        elif name == "note_on" and event[3] > 0:
-            c, p, v = event[2:5]
-            fl.noteon(c, p, v)
-        elif name == "note_off" or (name == "note_on" and event[3] == 0):
-            c, p = event[2:4]
-            fl.noteoff(c, p)
-
+    waveforms = []
+    for track_idx, track in enumerate(midi_opus[1:]):
+        ss = np.empty((0, 2), dtype=np.int16)
+        cur_t = 0
+        last_t = 0
+        fl.system_reset()
+        fl.get_samples(int(2 * sample_rate))  # get 2 seconds sample to eliminate reverb sound from previous track
+        for c in range(16):
+            fl.program_select(c, sfid, 128 if c == 9 else 0, 0)
+        for event in track:
+            name = event[0]
+            cur_t += event[1]
+            sample_len = int(((cur_t / ticks_per_beat) * tempo / (10 ** 6)) * sample_rate)
+            sample_len -= int(((last_t / ticks_per_beat) * tempo / (10 ** 6)) * sample_rate)
+            last_t = cur_t
+            if sample_len > 0:
+                sample = fl.get_samples(sample_len).reshape(sample_len, 2)
+                ss = np.concatenate([ss, sample])
+            if name == "set_tempo":
+                tempo = event[2]
+            elif name == "patch_change":
+                c, p = event[2:4]
+                fl.program_select(c, sfid, 128 if c == 9 else 0, p)
+            elif name == "control_change":
+                c, cc, v = event[2:5]
+                fl.cc(c, cc, v)
+            elif name == "note_on" and event[3] > 0:
+                c, p, v = event[2:5]
+                fl.noteon(c, p, v)
+            elif name == "note_off" or (name == "note_on" and event[3] == 0):
+                c, p = event[2:4]
+                fl.noteoff(c, p)
+        waveforms.append(ss)
     fl.delete()
-    return ss
+    synthesized = np.zeros((max([w.shape[0] for w in waveforms]), 2), dtype=np.int32)
+    for waveform in waveforms:
+        synthesized[:waveform.shape[0]] += waveform
+    max_val = np.abs(synthesized).max()
+    if max_val != 0:
+        synthesized = (synthesized / max_val) * np.iinfo(np.int16).max
+    synthesized = synthesized.astype(np.int16)
+
+    return synthesized