hyperframes/docs/guides/rendering.mdx

---
title: Rendering
description: "Render compositions to MP4 locally or in Docker."
---

Render your Hyperframes [compositions](/concepts/compositions) to MP4 with the [CLI](/packages/cli). The rendering pipeline is frame-by-frame and seek-driven — see [Deterministic Rendering](/concepts/determinism) for how this works under the hood.

## Getting Started

<Steps>
  <Step title="Verify your environment">
    Run the diagnostics command to check for required dependencies:

    ```bash Terminal
    npx hyperframes doctor
    ```

    Expected output:

    ```
    ✓ Node.js    v22.x
    ✓ FFmpeg      7.x
    ✓ FFprobe     7.x
    ✓ Chrome      (bundled)
    ✓ Docker      available
    ```
  </Step>
  <Step title="Preview your composition">
    Before rendering, preview your composition in the browser to verify it looks correct:

    ```bash Terminal
    npx hyperframes preview
    ```
  </Step>
  <Step title="Render to MP4">
    Run the render command from your project directory:

    ```bash Terminal
    npx hyperframes render --output output.mp4
    ```

    Expected output:

    ```
    ⠋ Rendering composition "root" (30fps, standard quality)
    ✓ Captured 240 frames in 8.2s
    ✓ Encoded to output.mp4 (8.0s, 1920x1080, 4.2MB)
    ```
  </Step>
</Steps>

## Rendering Modes

<Tabs>
  <Tab title="Local Mode">
    ### Local Mode (default)

    Uses Puppeteer (bundled Chromium) and your system's FFmpeg. Fast for iteration during development.

    **Requires:** FFmpeg installed on your system. See [Troubleshooting](/guides/troubleshooting) if FFmpeg is not found.

    ```bash Terminal
    npx hyperframes render --output output.mp4
    ```

    **Pros:**
    - Fast startup, no container overhead
    - Uses your system GPU for hardware-accelerated encoding (with `--gpu`)
    - Best for iterative development

    **Cons:**
    - Output may vary across platforms due to font and Chrome version differences
    - Not suitable for CI/CD pipelines that require reproducibility
  </Tab>
  <Tab title="Docker Mode">
    ### Docker Mode

    [Deterministic](/concepts/determinism) output with an exact Chrome version and font set. Use this for production renders and CI pipelines.

    **Requires:** Docker installed and running.

    ```bash Terminal
    npx hyperframes render --docker --output output.mp4
    ```

    **Pros:**
    - Identical output on every platform — same Chrome, same fonts, same FFmpeg
    - The same pipeline used in production
    - Ideal for CI/CD and automated workflows

    **Cons:**
    - Slower startup due to container initialization
    - No GPU acceleration inside the container

    <Note>
      Docker mode uses `chrome-headless-shell` with [BeginFrame](/concepts/determinism#how-it-works) control for frame-perfect, deterministic capture.
    </Note>
  </Tab>
</Tabs>

## When to Use Each Mode

| Scenario | Recommended Mode |
|----------|-----------------|
| Local development and iteration | Local |
| CI/CD pipeline | Docker |
| Sharing renders with a team | Docker |
| Quick preview export | Local |
| AI agent-driven rendering | Docker |
| Benchmarking performance | Local |

## Options

| Flag | Values | Default | Description |
|------|--------|---------|-------------|
| `--output` | path | `renders/<name>.mp4` | Output file path |
| `--fps` | 24, 30, 60 | 30 | Frames per second |
| `--quality` | draft, standard, high | standard | Encoding quality preset |
| `--workers` | 1-8 or `auto` | auto | Parallel render workers (see [Workers](#workers) below) |
| `--gpu` | — | off | GPU encoding (NVENC, VideoToolbox, VAAPI) |
| `--docker` | — | off | Use Docker for [deterministic rendering](/concepts/determinism) |
| `--quiet` | — | off | Suppress verbose output |

## Workers

Each render worker launches a **separate Chrome browser process** to capture frames in parallel. More workers can speed up rendering, but each one consumes ~256 MB of RAM and significant CPU.

### Default behavior

By default, Hyperframes uses **half of your CPU cores, capped at 4**:

| Machine | CPU cores | Default workers |
|---------|-----------|----------------|
| MacBook Air (M1) | 8 | 4 |
| MacBook Pro (M3) | 12 | 4 (capped) |
| 4-core laptop | 4 | 2 |
| 2-core VM | 2 | 1 |

This is intentionally conservative. Each worker spawns its own Chrome process, so the per-worker overhead is significant. Fewer workers avoids resource contention with FFmpeg encoding and your other applications.

### Choosing a worker count

```bash Terminal
# Explicit worker count
npx hyperframes render --workers 1 --output output.mp4

# Let Hyperframes pick based on your CPU
npx hyperframes render --workers auto --output output.mp4

# Maximum parallelism (use with caution on laptops)
npx hyperframes render --workers 8 --output output.mp4
```

<Tip>
  Start with the default. If renders feel slow and your system has headroom (check Activity Monitor / `htop`), try increasing `--workers`. If you see high memory pressure or fan noise, reduce it.
</Tip>

### When to use 1 worker

- Short compositions (under 2 seconds / 60 frames) — parallelism overhead exceeds the benefit
- Low-memory machines (4 GB or less)
- Running renders alongside other heavy processes (video editing, large builds)

### When to increase workers

- Long compositions (30+ seconds) on a machine with 8+ cores and 16+ GB RAM
- Dedicated render machines or CI runners
- Docker mode on a well-provisioned host

## Tips

<Tip>
  Use `draft` quality during development for fast previews. Switch to `standard` or `high` for final output.
</Tip>

- Use `npx hyperframes benchmark` to find optimal settings for your system
- Docker mode is slower but guarantees [identical output](/concepts/determinism) across platforms
- For compositions with many frames, `--gpu` can significantly speed up local encoding

## Next Steps

<CardGroup cols={2}>
  <Card title="Deterministic Rendering" icon="lock" href="/concepts/determinism">
    Understand the determinism guarantees
  </Card>
  <Card title="CLI Reference" icon="terminal" href="/packages/cli">
    Full list of CLI commands and flags
  </Card>
  <Card title="Troubleshooting" icon="wrench" href="/guides/troubleshooting">
    Fix common rendering issues
  </Card>
  <Card title="Common Mistakes" icon="triangle-exclamation" href="/guides/common-mistakes">
    Avoid pitfalls that affect render output
  </Card>
</CardGroup>