Code Editor for app.py

import streamlit as st
import numpy as np
import pygame
import time
from io import BytesIO

# Initialize pygame mixer
pygame.mixer.init()

def get_piano_note_freq(note):
    # A4 = 440Hz
    A4 = 440
    notes = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B']
    octave = int(note[-1])
    note_name = note[:-1]
    note_index = notes.index(note_name)
    
    # Calculate semitones from A4
    semitones_from_a4 = (octave - 4) * 12 + note_index - notes.index('A')
    
    # Calculate frequency using the formula: f = 440 * (2^(n/12))
    freq = A4 * (2 ** (semitones_from_a4 / 12))
    return freq

def generate_sine_wave(freq, duration=0.5, sample_rate=44100):
    t = np.linspace(0, duration, int(sample_rate * duration))
    wave = np.sin(2 * np.pi * freq * t)
    # Apply fade out
    fade = np.linspace(1, 0, len(wave))
    wave = wave * fade
    # Normalize and convert to 16-bit integer
    wave = np.int16(wave * 32767)
    return wave

def play_note(note):
    freq = get_piano_note_freq(note)
    wave = generate_sine_wave(freq)
    # Convert wave to bytes
    buffer = wave.tobytes()
    sound = pygame.mixer.Sound(buffer)
    sound.play()

st.title("🎹 Virtual Piano")
st.write("Click on the keys to play!")

# Define piano keys (2 octaves)
white_keys = ['C4', 'D4', 'E4', 'F4', 'G4', 'A4', 'B4', 
              'C5', 'D5', 'E5', 'F5', 'G5', 'A5', 'B5']
black_keys = ['C#4', 'D#4', 'F#4', 'G#4', 'A#4',
              'C#5', 'D#5', 'F#5', 'G#5', 'A#5']

# Create two rows of buttons
col1, col2 = st.columns([4, 1])

with col1:
    st.write("White keys:")
    cols = st.columns(len(white_keys))
    for i, note in enumerate(white_keys):
        with cols[i]:
            if st.button(note, key=f"white_{note}", use_container_width=True):
                play_note(note)

with col2:
    st.write("Black keys:")
    cols = st.columns(len(black_keys))
    for i, note in enumerate(black_keys):
        with cols[i]:
            if st.button(note, key=f"black_{note}", use_container_width=True):
                play_note(note)

st.markdown("""
### How to play:
1. Click on any key to hear its sound
2. White keys are the natural notes (C, D, E, F, G, A, B)
3. Black keys are the sharp notes (C#, D#, F#, G#, A#)
4. The number after each note represents the octave

### Tips:
- Try playing different combinations of notes
- The piano covers two octaves (4 and 5)
- Each key produces a pure sine wave tone
""")