Clean up code and rename to yue

1 files changed, 69 insertions, 0 deletions

diff --git a/yue.py b/yue.py
new file mode 100644
index 0000000..dda9e79
--- /dev/null
+++ b/yue.py
@@ -0,0 +1,69 @@
+import bisect
+import math
+import struct
+import sys
+
+# Number of times to sample each second
+bitrate = 44100
+music = []
+
+
+def process(notes, start, speed=1, gain=1, blend=0):
+    """
+    Adds a list of notes to the music list
+    """
+    t = start
+    for note in notes:
+        vol = 1
+        if len(note) == 4:
+            vol = note[3]
+        start = min(t, t + note[0] / speed)
+        end = max(t, t + note[0] / speed)
+        music.append((start, end + 16 * int(blend), note[1], note[2], vol * gain))
+        t = end
+
+
+def freq(octave, step):
+    """
+    Returns the frequency of a note
+    """
+    return 55 * 2 ** (octave + step / 12 - 1)
+
+
+def tone(f, t):
+    """
+    Returns the intensity of a tone of frequency f sampled at time t
+    https://dsp.stackexchange.com/questions/46598/mathematical-equation-for-the-sound-wave-that-a-piano-makes
+    https://youtu.be/ogFAHvYatWs?t=254
+    """
+    w = 2 * math.pi * f
+    Y = 0.6 * math.sin(w * t) * math.exp(-0.001 * w * t)
+    Y += 0.2 * math.sin(2 * w * t) * math.exp(-0.001 * w * t)
+    Y += 0.05 * math.sin(3 * w * t) * math.exp(-0.001 * w * t)
+    Y += Y * Y * Y
+    Y *= 1 + 16 * t * math.exp(-6 * t)
+    return Y
+
+
+def at(t):
+    """
+    Returns the total intensity of music sampled at time t
+    This is actually pretty efficient ngl
+    Because people usually don't have that many overlapping notes
+    """
+    i = bisect.bisect(music, (t, 2**31))
+    ret = 0
+    for j in range(max(i - 32, 0), i):
+        m = music[j]
+        if m[1] > t:
+            ret += m[4] * tone(freq(m[2], m[3]), t - m[0])
+    return int(2**28 * ret)
+
+
+def play(start, end):
+    """
+    Print music from the start time to end time encoded in s32 to standard output
+    """
+    music.sort()
+    for i in range(start * bitrate, end * bitrate):
+        sys.stdout.buffer.write(struct.pack("i", at(i / bitrate)))