Export Pipeline

PNG Export

In-Sketch (Keyboard Shortcut)

javascript

function keyPressed() {
  if (key === 's' || key === 'S') {
    saveCanvas('output', 'png');
    // Downloads output.png immediately
  }
}

Timed Export (Static Generative)

javascript

function setup() {
  createCanvas(3840, 2160);
  pixelDensity(1);
  randomSeed(CONFIG.seed);
  noiseSeed(CONFIG.seed);
  noLoop();
}

function draw() {
  // ... render everything ...
  saveCanvas('output-seed-' + CONFIG.seed, 'png');
}

High-Resolution Export

For resolutions beyond screen size, use pixelDensity() or a large offscreen buffer:

javascript

function exportHighRes(scale) {
  let buffer = createGraphics(width * scale, height * scale);
  buffer.scale(scale);
  // Re-render everything to buffer at higher resolution
  renderScene(buffer);
  buffer.save('highres-output.png');
}

Batch Seed Export

javascript

function exportBatch(startSeed, count) {
  for (let i = 0; i < count; i++) {
    CONFIG.seed = startSeed + i;
    randomSeed(CONFIG.seed);
    noiseSeed(CONFIG.seed);
    // Render
    background(0);
    renderScene();
    saveCanvas('seed-' + nf(CONFIG.seed, 5), 'png');
  }
}

GIF Export

saveGif()

javascript

function keyPressed() {
  if (key === 'g' || key === 'G') {
    saveGif('output', 5);
    // Captures 5 seconds of animation
    // Options: saveGif(filename, duration, options)
  }
}

// With options
saveGif('output', 5, {
  delay: 0,        // delay before starting capture (seconds)
  units: 'seconds' // or 'frames'
});

Limitations:

GIF is 256 colors max — dithering artifacts on gradients
Large canvases produce huge files
Use a smaller canvas (640x360) for GIF, higher for PNG/MP4
Frame rate is approximate

Optimal GIF Settings

javascript

// For GIF output, use smaller canvas and lower framerate
function setup() {
  createCanvas(640, 360);
  frameRate(15);  // GIF standard
  pixelDensity(1);
}

Frame Sequence Export

saveFrames()

javascript

function keyPressed() {
  if (key === 'f') {
    saveFrames('frame', 'png', 10, 30);
    // 10 seconds, 30 fps → 300 PNG files
    // Downloads as individual files (browser may block bulk downloads)
  }
}

Manual Frame Export (More Control)

javascript

let recording = false;
let frameNum = 0;
const TOTAL_FRAMES = 300;

function keyPressed() {
  if (key === 'r') recording = !recording;
}

function draw() {
  // ... render frame ...

  if (recording) {
    saveCanvas('frame-' + nf(frameNum, 4), 'png');
    frameNum++;
    if (frameNum >= TOTAL_FRAMES) {
      recording = false;
      noLoop();
      console.log('Recording complete: ' + frameNum + ' frames');
    }
  }
}

Deterministic Capture (Critical for Video)

The noLoop() + redraw() pattern is required for frame-perfect headless capture. Without it, p5's draw loop runs freely in Chrome while Puppeteer screenshots are slow — the sketch runs ahead and you get duplicate/missing frames.

javascript

function setup() {
  createCanvas(1920, 1080);
  pixelDensity(1);
  noLoop();                    // STOP the automatic draw loop
  window._p5Ready = true;      // Signal to capture script
}

function draw() {
  // This only runs when redraw() is called by the capture script
  // frameCount increments exactly once per redraw()
}

The bundled scripts/export-frames.js detects window._p5Ready and switches to deterministic mode automatically. Without it, falls back to timed capture (less precise).

ffmpeg: Frames to MP4

bash

# Basic encoding
ffmpeg -framerate 30 -i frame-%04d.png -c:v libx264 -pix_fmt yuv420p output.mp4

# High quality
ffmpeg -framerate 30 -i frame-%04d.png \
  -c:v libx264 -preset slow -crf 18 -pix_fmt yuv420p \
  output.mp4

# With audio
ffmpeg -framerate 30 -i frame-%04d.png -i audio.mp3 \
  -c:v libx264 -c:a aac -shortest \
  output.mp4

# Loop for social media (3 loops)
ffmpeg -stream_loop 2 -i output.mp4 -c copy output-looped.mp4

Video Export Gotchas

YUV420 clips dark values. H.264 encodes in YUV420 color space, which rounds dark RGB values. Content below RGB(8,8,8) may become pure black. Subtle dark details (dim particle trails, faint noise textures) disappear in the encoded video even though they're visible in the PNG frames.

Fix: Ensure minimum brightness of ~10 for any visible content. Test by encoding a few frames and comparing the MP4 frame vs the source PNG.

bash

# Extract a frame from MP4 for comparison
ffmpeg -i output.mp4 -vf "select=eq(n\,100)" -vframes 1 check.png

Static frames look broken in video. If an algorithm produces a single static image (like a pre-computed attractor heatmap), it reads as a freeze/glitch in video. Always add animation even to static content:

Progressive reveal (expand from center, sweep across)
Slow parameter drift (rotate color mapping, shift noise offset)
Camera-like motion (slow zoom, slight pan)
Overlay animated particles or grain

Scene transitions are mandatory. Hard cuts between visually different scenes are jarring. Use fade envelopes:

javascript

const FADE_FRAMES = 15;  // half-second at 30fps
let fade = 1;
if (localFrame < FADE_FRAMES) fade = localFrame / FADE_FRAMES;
if (localFrame > SCENE_FRAMES - FADE_FRAMES) fade = (SCENE_FRAMES - localFrame) / FADE_FRAMES;
fade = fade * fade * (3 - 2 * fade);  // smoothstep
// Apply: multiply all alpha/brightness by fade

Per-Clip Architecture (Multi-Scene Videos)

For videos with multiple scenes, render each as a separate HTML file + MP4 clip, then stitch with ffmpeg. This enables re-rendering individual scenes without touching the rest.

Directory structure:

project/
├── capture-scene.js          # Shared: node capture-scene.js <html> <outdir> <frames>
├── render-all.sh             # Renders all + stitches
├── scenes/
│   ├── 00-intro.html         # Each scene is self-contained
│   ├── 01-particles.html
│   ├── 02-noise.html
│   └── 03-outro.html
└── clips/
    ├── 00-intro.mp4          # Each clip rendered independently
    ├── 01-particles.mp4
    ├── 02-noise.mp4
    ├── 03-outro.mp4
    └── concat.txt

Stitch clips with ffmpeg concat:

bash

# concat.txt (order determines final sequence)
file '00-intro.mp4'
file '01-particles.mp4'
file '02-noise.mp4'
file '03-outro.mp4'

# Lossless stitch (all clips must have same codec/resolution/fps)
ffmpeg -f concat -safe 0 -i concat.txt -c copy final.mp4

Re-render a single scene:

bash

node capture-scene.js scenes/01-particles.html clips/01-particles 150
ffmpeg -y -framerate 30 -i clips/01-particles/frame-%04d.png \
  -c:v libx264 -preset slow -crf 16 -pix_fmt yuv420p clips/01-particles.mp4
# Then re-stitch
ffmpeg -y -f concat -safe 0 -i clips/concat.txt -c copy final.mp4

Re-order without re-rendering: Just change the order in concat.txt and re-stitch. No frames need re-rendering.

Each scene HTML must:

Call noLoop() in setup and set window._p5Ready = true
Use frameCount-based timing (not millis()) for deterministic output
Handle its own fade-in/fade-out envelope
Be fully self-contained (no shared state between scenes)

ffmpeg: Frames to GIF (Better Quality)

bash

# Generate palette first for optimal colors
ffmpeg -i frame-%04d.png -vf "fps=15,palettegen=max_colors=256" palette.png

# Render GIF using palette
ffmpeg -i frame-%04d.png -i palette.png \
  -lavfi "fps=15 [x]; [x][1:v] paletteuse=dither=bayer:bayer_scale=3" \
  output.gif

Headless Export (Puppeteer)

For automated, server-side, or CI rendering. Uses a headless Chrome browser to run the sketch.

export-frames.js (Node.js Script)

See scripts/export-frames.js for the full implementation. Basic pattern:

javascript

const puppeteer = require('puppeteer');

async function captureFrames(htmlPath, outputDir, options) {
  const browser = await puppeteer.launch({
    headless: true,
    args: ['--no-sandbox', '--disable-setuid-sandbox']
  });
  const page = await browser.newPage();

  await page.setViewport({
    width: options.width || 1920,
    height: options.height || 1080,
    deviceScaleFactor: 1
  });

  await page.goto(`file://${path.resolve(htmlPath)}`, {
    waitUntil: 'networkidle0'
  });

  // Wait for sketch to initialize
  await page.waitForSelector('canvas');
  await page.waitForTimeout(1000);

  for (let i = 0; i < options.frames; i++) {
    const canvas = await page.$('canvas');
    await canvas.screenshot({
      path: path.join(outputDir, `frame-${String(i).padStart(4, '0')}.png`)
    });

    // Advance one frame
    await page.evaluate(() => { redraw(); });
    await page.waitForTimeout(1000 / options.fps);
  }

  await browser.close();
}

render.sh (Full Pipeline)

See scripts/render.sh for the complete render script. Pipeline:

1. Launch Puppeteer → open sketch HTML
2. Capture N frames as PNG sequence
3. Pipe to ffmpeg → encode H.264 MP4
4. Optional: add audio track
5. Clean up temp frames

SVG Export

Using p5.js-svg Library

html

<script src="https://unpkg.com/[email protected]"></script>

javascript

function setup() {
  createCanvas(1920, 1080, SVG);  // SVG renderer
  noLoop();
}

function draw() {
  // Only vector operations (no pixels, no blend modes)
  stroke(0);
  noFill();
  for (let i = 0; i < 100; i++) {
    let x = random(width);
    let y = random(height);
    ellipse(x, y, random(10, 50));
  }
  save('output.svg');
}

Limitations:

No loadPixels(), updatePixels(), filter(), blendMode()
No WebGL
No pixel-level effects
Great for: line art, geometric patterns, plots

Hybrid: Raster Background + SVG Overlay

Render background effects to PNG, then SVG for crisp vector elements on top.

Export Format Decision Guide

Need	Format	Method
Single still image	PNG	`saveCanvas()` or `keyPressed()`
Print-quality still	PNG (high-res)	`pixelDensity(1)` + large canvas
Short animated loop	GIF	`saveGif()`
Long animation	MP4	Frame sequence + ffmpeg
Social media video	MP4	`scripts/render.sh`
Vector/print	SVG	p5.js-svg renderer
Batch variations	PNG sequence	Seed loop + `saveCanvas()`
Interactive deployment	HTML	Single self-contained file
Headless rendering	PNG/MP4	Puppeteer + ffmpeg

Tiling for Ultra-High-Resolution

For resolutions too large for a single canvas (e.g., 10000x10000 for print):

javascript

function renderTiled(totalW, totalH, tileSize) {
  let cols = ceil(totalW / tileSize);
  let rows = ceil(totalH / tileSize);

  for (let ty = 0; ty < rows; ty++) {
    for (let tx = 0; tx < cols; tx++) {
      let buffer = createGraphics(tileSize, tileSize);
      buffer.push();
      buffer.translate(-tx * tileSize, -ty * tileSize);
      renderScene(buffer, totalW, totalH);
      buffer.pop();
      buffer.save(`tile-${tx}-${ty}.png`);
      buffer.remove();  // free memory
    }
  }
  // Stitch with ImageMagick:
  // montage tile-*.png -tile 4x4 -geometry +0+0 final.png
}

CCapture.js — Deterministic Video Capture

The built-in saveFrames() has limitations: small frame counts, memory issues, browser download blocking. CCapture.js solves all of these by hooking into the browser's timing functions to simulate constant time steps regardless of actual render speed.

html

<script src="https://cdn.jsdelivr.net/npm/ccapture.js-npmfixed/build/CCapture.all.min.js"></script>

Basic Setup

javascript

let capturer;
let recording = false;

function setup() {
  createCanvas(1920, 1080);
  pixelDensity(1);

  capturer = new CCapture({
    format: 'webm',       // 'webm', 'gif', 'png', 'jpg'
    framerate: 30,
    quality: 99,           // 0-100 for webm/jpg
    // timeLimit: 10,      // auto-stop after N seconds
    // motionBlurFrames: 4 // supersampled motion blur
  });
}

function draw() {
  // ... render frame ...

  if (recording) {
    capturer.capture(document.querySelector('canvas'));
  }
}

function keyPressed() {
  if (key === 'c') {
    if (!recording) {
      capturer.start();
      recording = true;
      console.log('Recording started');
    } else {
      capturer.stop();
      capturer.save();  // triggers download
      recording = false;
      console.log('Recording saved');
    }
  }
}

Format Comparison

Format	Quality	Size	Browser Support
WebM	High	Medium	Chrome only
GIF	256 colors	Large	All (via gif.js worker)
PNG sequence	Lossless	Very large (TAR)	All
JPEG sequence	Lossy	Large (TAR)	All

Important: Timing Hook

CCapture.js overrides Date.now(), setTimeout, requestAnimationFrame, and performance.now(). This means:

millis() returns simulated time (perfect for recording)
deltaTime is constant (1000/framerate)
Complex sketches that take 500ms per frame still record at smooth 30fps
Caveat: Audio sync breaks (audio plays in real-time, not simulated time)

Programmatic Export (canvas API)

For custom export workflows beyond saveCanvas():

javascript

// Canvas to Blob (for upload, processing)
document.querySelector('canvas').toBlob((blob) => {
  // Upload to server, process, etc.
  let url = URL.createObjectURL(blob);
  console.log('Blob URL:', url);
}, 'image/png');

// Canvas to Data URL (for inline embedding)
let dataUrl = document.querySelector('canvas').toDataURL('image/png');
// Use in  or send as base64

SVG Export (p5.js-svg)

html

<script src="https://unpkg.com/[email protected]"></script>

javascript

function setup() {
  createCanvas(1920, 1080, SVG);  // SVG renderer
  noLoop();
}

function draw() {
  // Only vector operations work (no pixel ops, no blendMode)
  stroke(0);
  noFill();
  for (let i = 0; i < 100; i++) {
    ellipse(random(width), random(height), random(10, 50));
  }
  save('output.svg');
}

Critical SVG caveats:

Must call clear() in draw() for animated sketches — SVG DOM accumulates child elements, causing memory bloat
blendMode() is not implemented in SVG renderer
filter(), loadPixels(), updatePixels() don't work
Requires p5.js 1.11.x — not compatible with p5.js 2.x
Perfect for: line art, geometric patterns, pen plotter output

Platform Export

fxhash Conventions

javascript

// Replace p5's random with fxhash's deterministic PRNG
const rng = $fx.rand;

// Declare features for rarity/filtering
$fx.features({
  'Palette': paletteName,
  'Complexity': complexity > 0.7 ? 'High' : 'Low',
  'Has Particles': particleCount > 0
});

// Declare on-chain parameters
$fx.params([
  { id: 'density', name: 'Density', type: 'number',
    options: { min: 1, max: 100, step: 1 } },
  { id: 'palette', name: 'Palette', type: 'select',
    options: { options: ['Warm', 'Cool', 'Mono'] } },
  { id: 'accent', name: 'Accent Color', type: 'color' }
]);

// Read params
let density = $fx.getParam('density');

// Build: npx fxhash build → upload.zip
// Dev: npx fxhash dev → localhost:3300

Art Blocks / Generic Platform

javascript

// Platform provides a hash string
const hash = tokenData.hash;  // Art Blocks convention

// Build deterministic PRNG from hash
function prngFromHash(hash) {
  let seed = parseInt(hash.slice(0, 16), 16);
  // xoshiro128** or similar
  return function() { /* ... */ };
}

const rng = prngFromHash(hash);