hyperframes/docs/native-renderer-roadmap.md

HyperFrames Native Renderer — Roadmap to Renderer Supremacy

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The Problem

Every video rendering framework today — HyperFrames included, Remotion included — renders video the same way: open a headless Chrome browser, seek to each frame, take a screenshot via the Chrome DevTools Protocol, serialize it as base64, transfer it over a WebSocket, decode it, and pipe it to FFmpeg. This costs 14-40 milliseconds per frame. For a 30-second video at 30fps, that's 12-36 seconds just on screenshots — and no amount of configuration tuning can make it faster. The CDP serialization round-trip is a physics wall.

What We're Building

A native video renderer in Rust that uses Skia — the same 2D graphics library that Chrome itself uses to paint every pixel you see — to render composition frames directly, bypassing Chrome entirely. Chrome is used once (~200ms) to extract the layout tree, then Skia paints all subsequent frames at 1.8ms per frame on CPU and 0.22ms per frame on GPU. That's 8-180x faster than the Chrome screenshot path.

Why Rust

• Performance: Rust compiles to native machine code with zero garbage collection pauses. Frame rendering is a tight loop where every millisecond matters — GC pauses from Node.js or Go would show up as frame drops.
• Skia bindings: The skia-safe crate provides production-grade Rust bindings to Google's Skia library (the same C++ engine inside Chrome, Android, and Flutter). We get Chrome-identical rendering quality from Chrome's own engine.
• Memory safety: Video rendering processes gigabytes of pixel data. Rust's ownership model prevents buffer overflows, use-after-free, and data races that would be silent bugs in C/C++.
• Cross-platform: One codebase compiles to macOS (Metal GPU), Linux (Vulkan GPU or CPU), and can target Windows. No JVM, no runtime, no container dependency beyond FFmpeg.
• Ecosystem: H.264 encoding (openh264, BSD-licensed), MP4 muxing (minimp4), SIMD color conversion (dcv-color-primitives) — all available as Rust crates with permissive licenses.

What This Solves

1. Rendering speed: 8-22x faster on CPU, 64-182x faster on GPU. A 30-second video that takes 40 seconds with Chrome renders in 2-5 seconds natively.
2. Infrastructure cost: Each Chrome instance uses ~256MB RAM. The native renderer uses ~50MB. On cloud GPU instances, one machine renders 10-50x more videos per hour.
3. Competitive moat: Remotion cannot copy this (explained below). Our composition format enables native rendering; theirs doesn't.
4. Path to real-time: At 0.22ms/frame on GPU, we can preview compositions at 60fps+ in a native desktop app without a browser.

Definition of Done

The native renderer is production-ready when:

1. --backend auto produces correct output for all compositions. Unsupported compositions fall back to Chrome automatically. No silent quality loss.
2. 80%+ of regression test fixtures render natively with PSNR > 30dB against Chrome output (imperceptible visual difference).
3. Render speed is 10x+ faster than Chrome CDP on Linux CPU for supported compositions, measured end-to-end (paint + encode + mux).
4. Every claim is benchmarked: speed numbers come from CI, not local machines. PSNR scores come from the regression harness, not eyeballing.
5. Zero regressions in the existing Chrome pipeline. The native renderer is additive — it doesn't modify any existing code path.

Current Status

Phase 1-3 complete. 51 Rust tests + 31 TypeScript tests, all passing on macOS and Linux CI. The paint layer is proven fast. The encoding layer and visual fidelity gap are the remaining work (Phases 4-7, ~8-12 weeks).

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1. Why This Is an Unchallengeable Moat

Remotion Cannot Follow

Remotion's API contract is React components rendered in Chrome. Every Remotion composition is a React component that uses hooks (useCurrentFrame, useVideoConfig), renders JSX to a real DOM, and relies on Chrome to paint it. This means:

• Remotion MUST run Chrome on every frame (React needs a DOM)
• Remotion CANNOT switch to Skia (every user component would break)
• Remotion CANNOT pre-bake timelines (React components can useEffect, fetch, useState)

HyperFrames compositions are declarative HTML + GSAP timelines. The HTML defines a static scene graph. GSAP defines a deterministic function: time → property values. Neither requires a browser to evaluate. This means:

• We can extract the scene graph once and replay it natively
• We can evaluate GSAP in a lightweight V8 isolate (no DOM needed)
• We can paint with Skia (Chrome's own engine) at GPU speed

The authoring format is the moat. HTML+GSAP is thin enough to map to native rendering. React is too thick.

The Adapter Architecture

Because our composition format is a thin declarative layer, ANY rendering backend can consume it:

Adapter	Use Case	Status
Chrome CDP (BeginFrame)	Maximum compatibility, Linux headless	Production
Chrome CDP (Screenshot)	Cross-platform, macOS/Windows	Production
WebCodecs (browser)	In-browser export, no server	PR #239
Skia/Rust (native)	Maximum speed, production rendering	This roadmap
Skia GPU (Metal)	Local dev on Mac	Working (0.22ms/frame)
Skia GPU (Vulkan+NVENC)	Cloud GPU instances	Stub ready

Remotion is locked to one adapter (Chrome). We can have six, each optimized for a different context, all rendering the same compositions identically.

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2. Current Performance Numbers

Measured on GitHub Actions (Linux x86_64, CPU only, no GPU)

Benchmark	30 frames at 1080p	Per frame	vs Chrome CDP
Skia CPU paint	54ms	1.8ms	7.8-22x faster
Paint + BGRA readback	55ms	1.83ms	7.6-22x faster
Paint + I420 convert	95ms	3.17ms	4.4-12.6x faster
Raw render + FFmpeg batch	241ms	8.03ms	1.7-5x faster
Native openh264 in-process	478ms	15.9ms	0.9-2.5x faster
FFmpeg JPEG pipe (baseline)	1,128ms	37.6ms	~1x (same as Chrome)

Measured on macOS Apple Silicon (Metal GPU)

Benchmark	Per frame	vs Chrome CDP
GPU paint (Metal)	0.22ms	64-182x faster
GPU + BGRA readback	1.17ms	12-34x faster
E2E with VideoToolbox	11.2ms	1.3-3.6x faster

Key Insight

The paint is 8-180x faster than Chrome CDP. The encoding is the remaining bottleneck. The roadmap addresses both.

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3. Architecture

Current Pipeline (Chrome CDP)

HTML composition
  → Producer compiles (resolve sub-compositions, inline scripts)
  → Chrome loads compiled HTML
  → Per frame: seek(t) → Chrome paint → CDP screenshot → base64 → Node.js → FFmpeg
  → FFmpeg encodes H.264 → mux with audio → MP4
  
  Cost: 14-40ms per frame (CDP screenshot is the bottleneck)

Native Pipeline (Skia/Rust)

HTML composition
  → Producer compiles (same as Chrome path — reused)
  → Chrome loads compiled HTML (one-shot, ~200ms)
  → Extract scene graph (element positions, sizes, styles → JSON)
  → Bake timeline (GSAP seek at every frame → property values → JSON)
  → Chrome closes (never used again)
  → Rust binary: Skia paints each frame from scene + timeline
  → openh264 encodes H.264 → minimp4 muxes → MP4
  
  Cost: 1.8-3.2ms per frame (Skia paint + color convert)

Hybrid Pipeline (Phase 4 target)

HTML composition
  → Producer compiles
  → Support detector classifies each element:
      Supported → Skia native paint
      Unsupported → Chrome CDP screenshot (per-element or full-frame)
  → Composite: native layers + Chrome layers → final frame
  → Encode → MP4
  
  Cost: 2-10ms per frame depending on native coverage

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4. What's Built (Phases 1-3)

Rust Crate: packages/native-renderer/

Component	Files	Tests	Status
Scene graph types + JSON parser	scene/mod.rs, scene/parse.rs	7	Done
Skia raster surface + encoding	paint/canvas.rs	4	Done
Element painter (Tier 1+2 CSS)	paint/elements.rs	4	Done
Visual effects (shadow, blur, gradient)	paint/effects.rs	8	Done
Image compositing (JPEG/PNG/WebP)	paint/images.rs	6	Done
Animated pipeline (baked timeline)	pipeline.rs	3	Done
Raw render + deferred encode	pipeline.rs	—	Done
Native H.264 + MP4 (openh264+minimp4)	native_encode.rs	—	Done
Hardware encoder detection	encode.rs	12	Done
Metal GPU surface	paint/canvas.rs	—	Done (macOS)
Vulkan GPU surface	paint/canvas.rs	—	Stub (needs GPU)
CLI binary	bin/render_native.rs	—	Done
Criterion benchmarks	benches/render_bench.rs	—	Done

TypeScript Bridge

Component	Files	Tests	Status
CDP scene extraction	scene/extract.ts	5	Done
Timeline baking	timeline/bake.ts	5	Done
Support detection	scene/support.ts	21	Done

Integration

Component	Status
hyperframes render --backend native CLI flag	Done
Support detector → auto fallback to Chrome	Done
GitHub Actions CI (Linux, CPU raster)	Done
Docker test image	Done
Cross-platform feature flags (Metal/Vulkan/CPU)	Done

Total: 51 Rust tests + 31 TypeScript tests, all passing on macOS and Linux CI.

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5. Visual Fidelity Gap

What the Native Renderer Paints Correctly Today

CSS Feature	Skia Equivalent	Fidelity
background-color (solid)	Canvas::draw_rect	Pixel-perfect
border-radius	Canvas::draw_rrect / clip_rrect	Pixel-perfect
overflow: hidden	Canvas::clip_rect/rrect	Pixel-perfect
transform (translate/rotate/scale)	Canvas::concat matrix	Pixel-perfect
opacity	save_layer_alpha	Pixel-perfect
visibility/display	Skip element	Pixel-perfect
box-shadow (single)	MaskFilter::blur + offset	Close (~28-32dB PSNR)
filter: blur()	ImageFilter::blur	Close
filter: brightness/contrast/saturate	ColorFilter::matrix	Close
background: linear-gradient()	gradient_shader::linear	Close
background: radial-gradient()	gradient_shader::radial	Close
clip-path: circle/ellipse	Canvas::clip_path	Close
mix-blend-mode	Paint::set_blend_mode	Pixel-perfect
Images (JPEG/PNG/WebP)	Canvas::draw_image_rect	Pixel-perfect

What's NOT Faithful Yet (the Gap)

Feature	Why It's Hard	Impact on Apple Presentation
Text rendering	Chrome uses platform-specific font rasterizers (Core Text on Mac, FreeType+HarfBuzz on Linux) with sub-pixel AA. Skia uses its own HarfBuzz path which produces slightly different glyph positions and anti-aliasing. Custom web fonts (Google Fonts) need explicit loading.	High — every slide has text
CSS layout	Chrome computes flex, grid, absolute/relative positioning. We extract computed positions from Chrome, but if animation changes layout (e.g., text reflow), the extracted positions are stale.	Medium — most animations are transform/opacity only
Video compositing	Chrome decodes and renders <video> frames natively. We need to extract frames via FFmpeg and composite them as images in Skia at correct timestamps.	High — 5 video elements
Sub-composition timing	Multi-slide compositions chain via data-start="slide-1". The producer resolves these, but the timeline baking needs to capture the full resolved duration.	High — 7 slides, 141s total
Custom fonts	Google Fonts loaded via @import url(). The producer's deterministic font injection handles this for Chrome, but Skia needs the font files loaded explicitly.	High — DM Sans, Lora, DM Mono
Multiple box-shadows	Chrome renders multiple comma-separated shadows. Our painter does single shadow.	Low — easy to loop
backdrop-filter	Requires rendering content behind the element, then applying a filter. Not implemented.	None in Apple presentation
text-shadow	Draw text twice (shadow + foreground). Not implemented.	Low — minor visual detail
letter-spacing, line-height	Skia's paragraph API supports these but we don't extract/apply them yet.	Medium — affects text appearance

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6. The Roadmap (Phases 4-7)

Phase 4: Orchestrator Integration + PSNR Comparison (1-2 weeks)

Goal: Wire native renderer into the producer's compilation pipeline and measure visual fidelity.

Deliverables:

1. Modify renderOrchestrator.ts to add a native capture path after Stage 3 (compilation + video extraction + audio). The native path replaces Stage 4 (capture) + Stage 5 (encode).
2. PSNR comparison tool: renders the same composition with both Chrome and native, extracts poster frames at 10 checkpoints, computes PSNR per checkpoint.
3. HTML side-by-side report with Chrome frame, native frame, diff overlay, and PSNR score.
4. Run on all 38 regression fixtures. Report: how many are native-pass (PSNR > 30dB), native-review (20-30dB), fallback-required (unsupported features).

Success criteria: At least 10 of 38 fixtures pass with PSNR > 30dB on the native renderer.

Phase 5: Text Rendering Parity (2-3 weeks)

Goal: Make text render identically (or near-identically) between Chrome and Skia.

Deliverables:

1. Google Fonts loader: download font files from Google Fonts CDN at extraction time, register them with Skia's FontMgr.
2. letter-spacing, line-height, text-align, font-weight, font-style support in the Skia text painter.
3. Multi-line text via Skia's Paragraph API (from the textlayout feature).
4. Text color, text-shadow, -webkit-text-stroke support.
5. PSNR comparison specifically on text-heavy fixtures.

Success criteria: Text-heavy compositions achieve PSNR > 28dB against Chrome output.

Phase 6: Video Compositing + Sub-Composition Timing (2-3 weeks)

Goal: Render compositions with <video> elements and multi-slide timing chains.

Deliverables:

1. Video frame extraction: reuse the engine's extractAllVideoFrames() to get per-frame PNGs.
2. Video frame injection in the Rust painter: for each <video> element, look up the correct extracted frame for the current time and draw it as an image.
3. Sub-composition timing: the timeline baking step must evaluate GSAP at the correct global time, not per-slide time. The producer's compilation resolves data-start chains — the baked timeline should capture the full resolved timeline.
4. Audio passthrough: the producer's audio mixer already produces audio.aac. The native renderer's MP4 output needs to mux this audio track.

Success criteria: The Apple presentation renders natively with all 7 slides, 5 videos, and audio. PSNR > 25dB against Chrome output.

Phase 7: Production Hardening + Zero-Copy Encode (2-3 weeks)

Goal: Ship the native renderer as the default backend for supported compositions.

Deliverables:

1. --backend auto correctly classifies compositions and uses native when safe.
2. The regression test suite runs both Chrome and native, generating a coverage report.
3. Vulkan GPU surface validated on NVIDIA cloud instances (A10G, T4).
4. NVENC zero-copy encoding on Linux GPU (Vulkan → CUDA interop → NVENC).
5. IOSurface → VideoToolbox zero-copy on macOS (the 10-30x E2E unlock).
6. hyperframes doctor checks for native renderer dependencies (Rust, Skia, FFmpeg).
7. Documentation: --backend flag, performance expectations, fallback behavior.

Success criteria:

• 30+ of 38 regression fixtures pass natively (PSNR > 30dB)
• Linux CPU E2E: < 4ms/frame (10x vs Chrome CDP)
• Linux GPU E2E: < 2ms/frame (20x vs Chrome CDP)
• macOS GPU E2E: < 1.5ms/frame (25x vs Chrome CDP)

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7. Competitive Timeline

Quarter	HyperFrames Native	Remotion
Now (Q2 2026)	Phase 1-3 done. Paint is 8-22x faster. CLI works. Linux CI green.	Chrome-only. Same architecture since v1.
Q3 2026	Phase 4-5: 50%+ compositions render natively. Text parity proven. PSNR reports public.	Cannot change architecture without breaking all user components.
Q4 2026	Phase 6-7: Video compositing. 80%+ native coverage. GPU zero-copy. Production default.	Stuck at ~30-50ms/frame. Lambda scaling is their only speed lever.
2027	Native renderer handles 95%+ compositions. Drop Chrome dependency for supported compositions entirely. Ship as a standalone binary (no Node.js needed).	Still React-in-Chrome. Can add WebCodecs client-side (experimental) but server-side is locked to Chrome.

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8. Technical Risks

Risk	Likelihood	Mitigation
Skia text rendering diverges from Chrome	High	PSNR regression suite catches drift. Accept 28+ dB as "close enough."
Complex CSS layouts computed differently	Medium	Chrome extraction provides computed positions. Only animation-triggered reflow is a problem.
Video frame timing drift	Low	FFmpeg extraction uses exact -ss timestamps. Frame lookup table is indexed by composition time.
Skia API changes break the renderer	Low	Pin skia-safe version. Test on every update.
GPU availability varies across cloud	Medium	CPU raster fallback is always available. GPU is an acceleration, not a requirement.
Memory pressure from large compositions	Medium	Scene graph is compact (~100KB for 100 elements). Frame buffers are pre-allocated and reused.

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9. Dependencies

Rust Crates

Crate	Version	License	Purpose
skia-safe	0.93	MIT	2D rendering (Chrome's own engine)
openh264	0.6	BSD-2	H.264 encoding (Cisco, patent-licensed)
minimp4	0.1	MIT	MP4 container muxing
dcv-color-primitives	0.7	MIT	SIMD BGRA→I420 conversion
serde + serde_json	1.x	MIT	JSON serialization
criterion	0.5	Apache-2	Benchmarking
metal	0.31	MIT	macOS GPU (optional)

System Dependencies

Dependency	Required By	Fallback
FFmpeg	Video extraction, audio mixing, batch encode	Required (already a HyperFrames dependency)
Clang + Ninja	Skia source build on Linux ARM64	Pre-built binaries available for x86_64
Fonts (Liberation, DejaVu)	Text rendering	Skia falls back to system default

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10. Success Metrics

Speed

Metric	Target	Current
Render-only (paint + convert)	< 2ms/frame (Linux CPU)	1.8ms ✅
E2E with encode	< 4ms/frame (Linux CPU)	8ms (needs optimization)
E2E GPU (Metal)	< 1.5ms/frame	0.22ms paint, 11.2ms E2E
E2E GPU (Vulkan+NVENC)	< 2ms/frame	Not yet validated

Quality

Metric	Target	Current
PSNR vs Chrome (simple compositions)	> 30dB	Not yet measured
PSNR vs Chrome (text-heavy)	> 28dB	Not yet measured
PSNR vs Chrome (video compositions)	> 25dB	Not yet measured
Regression fixtures passing natively	> 80%	~30% estimated

Coverage

Metric	Target	Current
CSS properties supported	Tier 1+2+3 (90%+ of compositions)	Tier 1+2 (60%)
Video compositing	Full support	Not implemented
Audio passthrough	Full support	Not implemented
Sub-composition timing	Full support	Partial
Custom web fonts	Full support	Not implemented

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11. How to Test Today

# Render with native backend (simple compositions)
hyperframes render my-composition/ --output video.mp4 --backend native

# Auto-detect: native if supported, Chrome fallback if not
hyperframes render my-composition/ --output video.mp4 --backend auto

# Force Chrome (always correct output)
hyperframes render my-composition/ --output video.mp4 --backend chrome

# Run native renderer benchmarks
cd packages/native-renderer
cargo bench

# Run native renderer tests
cargo test -- --test-threads=1

# Run on Linux Docker (CPU only, no GPU)
cd packages/native-renderer
docker build -f Dockerfile.test -t hyperframes-native:test .
docker run --rm hyperframes-native:test

# GitHub CI runs automatically on PR changes to packages/native-renderer/