Bytebeat Moog City Reconstruction v3.2: Technical Analysis and Implementation

Date: 2026-08-02

1. Project Overview

Bytebeat approximation of Moog City (archive, with timeout silence) 📌 This is a personal development archive recording a Bytebeat-based approximate reconstruction of Moog City, written in JavaScript and runnable directly in the Bytebeat composer. I’ll keep polishing it when I have time.

Moog City is a track by C418 from Minecraft - Volume Alpha, released on March 4, 2011, 02:40 long, Ambient style. The original features a looping ascending melody + Moog-style synth timbre, with piano entering mid-way, then strings building up before resolving.

Bytebeat is a minimalist form of generative music: a single expression over a time variable t directly generates the waveform, usually output at 8000Hz as 8-bit mono audio. Dollchan Bytebeat Composer is an online real-time editing player supporting several modes: classic Bytebeat (outputs 0–255 integers), Signed Bytebeat, Floatbeat (outputs -1.0 to 1.0), and JS-big mode (supports JavaScript Bytebeat code larger than 1KB). This archive’s code is JS-big / Floatbeat style, leveraging JS arrays, floating-point arithmetic, Math.random(), and so on.

Project status: runnable / work in progress (WIP), last updated 2026-07-22.

2. Core Architecture and Algorithm Principles

2.1 Time and Pitch Handling

Time scaling: t /= 6 slows down the raw time variable to form the piece’s base tempo.
Pitch mapping: uses the 12-TET formula 2**(p/12) to convert semitone indices into frequency multipliers.
Pitch quantization function: EqT = p => 32/d * round(d/32 * 2**(p/12 - 0.02)) quantizes the computed frequency onto a grid to keep pitches stable, while the -0.02 semitone adjustment simulates the slight detune of analog synths.

2.2 Waveform Generation and Silence Logic

Waveform generation: uses a triangle-wave variant of abs(modulation) % 4 - 2 (shown in the code as abs(t*M/8 % 4 - 2) - 1) to generate the lead and harmony layers.
Micro-rests: a silence gate (S = R > 6) triggers at step 7 of the 8-step sequence, injecting breathing room into the rhythm.
Global silence gate: when the sample count t exceeds MAX_T = 25000000, the IS_SILENT flag is set to true and multiplies every signal path, ensuring the output goes to zero.

2.3 Feedback Delay Line (Echo)

The project uses a feedback delay line (FDL) to create the echo effect:

Delay buffer: a is a ring array of length n ≈ d * 9 that stores historical audio samples.
Feedback injection: each frame’s mixed signal ev accumulates into the buffer at the current position: a[T % n] += ev.
Decay: the buffer value is then divided by 3 (a[T % n] /= 3), producing an exponentially decaying echo.
Mixed output: the final output ev is a mix of the dry signal and the attenuated delayed signal.

Lead volume: MV = t < 54864 ? t/128E3 : .42, implementing an opening fade-in.
Harmony volume: MV2 = (t > 164592 && t < 219456 ? (t-164592)/128E3 : .42) * (!S) * (!IS_SILENT), fading in mid-piece.
Bass volume: CV = (t > 274320 && !S) * .5 * (!IS_SILENT), cutting in at a specific time.

4. Full Source Code

MAX_T = 25000000,
IS_SILENT = t > MAX_T,
t?(t/=6,
  R=(0|t/d)%8,
  S=R>6,
  EqT=p=>32/d*round(d/32*2**(p/12-.02)),
  c=int((t+random()*D)/d)%8,
  M=EqT([5,10,12,17,20,24,27,32][c])*(!S)*(!IS_SILENT),
  M2=EqT([-7,-4,0,3,5,10,12,15][c])*(!S)*(!IS_SILENT),
  C=8*EqT([12,12,12,15,10,10,10,3,5,5,5,5,8,8,8,5,10,10,10,10,8,8,8,3,5,5,5,5,8,8,8,10][int((t+d*32+random()*D)/d/2)%32])*(!S)*(!IS_SILENT),
  MV=t<54864?t/128E3:.42,
  MV2=(t>164592&&t<219456?(t-164592)/128E3:.42)*(!S)*(!IS_SILENT),
  CV=(t>274320&&!S)*.5*(!IS_SILENT),
  ev=(abs(t*M/8%4-2)-1)*MV + (abs(t*M2/8%4-2)-1)*MV2/2 + t*C%256*CV/192 -.5 + a[T%n],
  a[T%n]+=ev,
  a[T%n]/=3,
  IS_SILENT ? 0 : ev/2
):(
  a=Array(n=round(d*6*1.5)).fill(0)
)```javascript



### 5. Known Issues and Future Work


#### 5.1 Known Issues


- **Macro-rests not implemented**: only the per-cycle micro-rests are implemented; structural silences based on absolute time are missing (e.g., the rests around 1:30 and 2:25).
- **Missing piano timbre layer**: the piano timbre from the original track hasn't been synthesized yet.
- **Missing string crescendo**: the string crescendo section from the original track is absent.



#### 5.2 Future Work Plan


- Implement structural silences based on absolute time.
- Add a second synthesis pass to generate the piano timbre.
- Refactor the pitch arrays to exactly match the standard frequencies of the E minor scale.
- Optimize code structure for better readability and maintainability.



### 6. Run and Debug Instructions

Copy the full code above into the JS-big mode editor of the [Dollchan Bytebeat Composer](https://dollchan.net/bytebeat/) and press play to hear the synthesis result. Watch out for the browser audio context to avoid automatic pausing.


Suggestions during development:



1. Use `console.log` to output key variables (such as `R`, `S`, `M`) to debug the timing logic.
2. Gradually comment out `IS_SILENT` or the volume envelopes to listen to each voice in isolation.
3. Try modifying `d` (the base tempo divisor), the delay feedback coefficient (currently 3), or the pitch arrays to explore different sounds.

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> Original version: https://k4m7v2pz.github.io/en/blog/programming/bytebeat-moog-city-reconstruction.html

K4m7v2pz's Blog

Bytebeat Moog City Reconstruction v3.2: Technical Analysis and Implementation

1. Project Overview

2. Core Architecture and Algorithm Principles

2.1 Time and Pitch Handling

2.2 Waveform Generation and Silence Logic

2.3 Feedback Delay Line (Echo)

3. Voices and Melody Structure

3.1 Lead

3.2 Harmony

3.3 Bass/Noise

3.4 Volume Envelopes

4. Full Source Code

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K4m7v2pz's Blog