Migrate WASM backend from Rust to Emscripten/embind libultrahdr#15
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Replace the in-house Rust UltraHDR reimplementation with a thin Emscripten/embind C++ wrapper around upstream google/libultrahdr, vendored as a git submodule pinned to commit 82b4f6da (the dual-license merge from google/libultrahdr#386). The Rust crate existed because libultrahdr was Apache-2.0-only and could not be redistributed under GPLv2-compatible terms. With upstream now dual-licensed Apache-2.0 OR MIT, building on the canonical implementation gives us spec-conformant behavior, ongoing security/perf maintenance, and a much smaller surface to own. Public JS API of the open-ultrahdr package is unchanged (same exports, signatures, and return shapes); only the implementation backend differs. Bumps both packages to 0.2.0 since the WASM binary identity changes. Build chain: emcmake + cmake + emcc, --use-port=libjpeg, MODULARIZE=1 + EXPORT_ES6=1, single-threaded, FILESYSTEM=0. WASM size 577 KB vs prior Rust 341 KB (+1.7x, well within the <2x budget noted in the issue). Test fixture sizes raised from 2x2 to 16x16 to satisfy libultrahdr's documented 8x8 minimum dimensions; the prior Rust impl's lax handling of tiny images was not spec-compliant. Refs #14
Mirror upstream libultrahdr's dual licensing now that google/libultrahdr#386 has shipped. Apache-2.0 OR MIT is far more permissive than GPL-2.0 and unlocks downstream consumers (notably WordPress/gutenberg) that need a permissive license for their own redistribution. LICENSE becomes a short preamble pointing at LICENSE-APACHE and LICENSE-MIT (the same layout libultrahdr uses). README's GPLv2 framing is replaced with the dual-license note. Per-package license fields were already updated to "Apache-2.0 OR MIT" in the migration commit. Refs #14
Replace the Rust + wasm-pack build steps with an emsdk + cmake build via mymindstorm/setup-emsdk@v14. Submodules are checked out recursively so libultrahdr is available to the build. Ts-lint, ts-typecheck, and the e2e matrix continue to consume the wasm artifact unchanged. Refs #14
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Caution Review failedPull request was closed or merged during review 📝 WalkthroughWalkthroughMigrates WASM backend from a Rust/wasm-pack build to an Emscripten/embind C++ build of upstream libultrahdr (vendored as a git submodule), rewrites JS WASM loader, updates CI/publish workflows for emsdk, converts license to Apache-2.0 OR MIT, and bumps package versions to 0.2.0. Tests and fixtures updated for larger synthetic images. ChangesWASM Backend and Licensing Migration
Sequence DiagramsequenceDiagram
participant JS as JS App Layer
participant Loader as getWasm()
participant Emscripten as Emscripten Module
participant Lib as libultrahdr (C++)
participant FS as Filesystem/Network
rect rgba(100, 200, 150, 0.5)
Note over JS,Loader: WASM Module Initialization
JS->>Loader: getWasm()
Loader->>Emscripten: dynamic import open-ultrahdr-wasm
alt explicitWasmUrl set
Emscripten->>FS: fetch(customUrl)
else Node with setLocation
Emscripten->>FS: fs.readFileSync(.wasm)
else browser default
Emscripten->>FS: locateFile resolver
end
FS-->>Emscripten: .wasm binary
Emscripten->>Emscripten: instantiate WASM, bind functions
Emscripten-->>Loader: OpenUltraHdrModule (cached)
Loader-->>JS: module instance
end
rect rgba(150, 150, 200, 0.5)
Note over JS,Emscripten: Encode Flow
JS->>Emscripten: encodeUltraHdr(sdrBytes, hdrFloats, options)
Emscripten->>Lib: parse JPEG, pack F32→F16, encode gainmap
Lib->>Lib: compute gainmap, create XMP/MPF, assemble JPEG
Lib-->>Emscripten: encoded JPEG bytes
Emscripten-->>JS: Uint8Array result
end
rect rgba(200, 150, 150, 0.5)
Note over JS,Emscripten: Decode Flow
JS->>Emscripten: decodeUltraHdr(jpegBuffer)
Emscripten->>Lib: parse XMP/MPF, extract gainmap & SDR
Lib->>Lib: decode gainmap, apply gains, return metadata
Lib-->>Emscripten: {sdr, gainmap, metadata, dims}
Emscripten-->>JS: UltraHdrDecodeResult
end
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Actionable comments posted: 4
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⚠️ Outside diff range comments (1)
js/__tests__/fixtures/test-data.ts (1)
74-78:⚠️ Potential issue | 🟡 Minor | ⚡ Quick winStale comment:
createMinimalJpegBufferstill says "2x2 JPEG".The function comment on Line 75 was not updated to reflect the fixture change to 16×16. Additionally, the function accepts
_widthand_heightparameters but unconditionally ignores them — any caller passing different dimensions will silently get the pre-encoded 16×16 JPEG back. Consider either removing the parameters (sinceREGULAR_JPEG_BASE64is public and callers can callbase64ToArrayBufferdirectly) or updating the comment to clarify the fixed-size behavior.🔧 Proposed fix
-export function createMinimalJpegBuffer(_width: number, _height: number): ArrayBuffer { - // Return the pre-encoded 2x2 JPEG for simplicity - // In a real scenario, we'd use a library like sharp or canvas +export function createMinimalJpegBuffer(): ArrayBuffer { + // Return the pre-encoded 16x16 JPEG fixture. + // For dynamic sizes, use a library like sharp or canvas. return base64ToArrayBuffer(REGULAR_JPEG_BASE64); }🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@js/__tests__/fixtures/test-data.ts` around lines 74 - 78, The comment for createMinimalJpegBuffer is stale and the function silently ignores its _width and _height parameters; update the comment to state it returns a pre-encoded 16×16 JPEG (from REGULAR_JPEG_BASE64) and explicitly document that the _width and _height args are ignored (or, if you can change callers, remove the unused parameters and let callers call base64ToArrayBuffer(REGULAR_JPEG_BASE64) directly); adjust the JSDoc/text in createMinimalJpegBuffer and keep REGULAR_JPEG_BASE64 and base64ToArrayBuffer references to make the intended fixed-size behavior clear.
🧹 Nitpick comments (1)
wasm/package.json (1)
48-48: ⚡ Quick winMake
wasmpackagetestrun real tests instead of a no-op.The current script always succeeds, which can mask regressions when contributors run
npm testfromwasm/.Suggested patch
- "test": "echo 'WASM tests run via the JS package (cd ../js && npm test)'" + "test": "cd ../js && npm test"🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@wasm/package.json` at line 48, Replace the no-op "test" script in wasm/package.json so it runs the real JS tests: update the "test" script value to invoke the JS package test runner (for example use "npm --prefix ../js test" or "npm --prefix ../js run test") so running npm test in wasm/ actually executes and fails on test failures; edit the "test" entry in package.json accordingly (look for the existing "test" script key).
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In @.github/workflows/ci.yml:
- Around line 23-37: The workflow's "Build WASM" step runs npm without a pinned
Node, causing runner drift; add a step before "Build WASM" that uses
actions/setup-node (e.g., actions/setup-node@v4) to set node-version to a fixed
value or an env var (e.g., NODE_VERSION) so npm runs on a deterministic Node;
ensure the new setup-node step appears before the "Build WASM" step so the "npm
run build" in that step uses the pinned Node runtime.
In `@js/src/index.ts`:
- Around line 67-88: The cache reset is vulnerable to races because resetCache()
nulled initPromise but in-flight getWasm() calls can still resolve and overwrite
wasmInstance; add an init generation token (e.g., increment a module-level
initGeneration whenever setLocation or setWasmUrl is called or resetCache runs)
and have getWasm capture the current generation when it starts and compare it
before assigning to wasmInstance or clearing initPromise so only the latest
generation can publish its result; update resetCache(), setLocation(),
setWasmUrl(), and getWasm() to use this token check and avoid publishing stale
in-flight initializations.
- Around line 149-166: The try/catch only wraps the call to wasm.probeUltraHdr
so failures from getWasm() still throw; move the await getWasm() call inside the
try in probeUltraHdr so both WASM initialization and probe execution are caught,
and on any error return the same default UltraHdrProbeResult; locate function
probeUltraHdr and the getWasm() invocation and wrap both in the single try block
that returns the invalid/default result on failure.
In `@wasm/src/bindings.cpp`:
- Around line 57-64: UltraHdrEncodeOptions contains includeIsoMetadata and
includeUltrahdrV1 but encodeUltraHdr() never uses them; update encodeUltraHdr()
to read these fields from UltraHdrEncodeOptions and either (preferred) pass them
into the underlying encoder/configuration API (e.g., set equivalent flags on the
encoder instance or encoder options used by encodeUltraHdr()) so metadata
emission respects includeIsoMetadata and includeUltrahdrV1, or if the encoder
cannot support them, validate and return/throw an explicit error when those
flags are set; locate UltraHdrEncodeOptions and the encodeUltraHdr()
implementation and wire these two boolean flags into the encoder configuration
or add validation logic to reject unsupported combinations.
---
Outside diff comments:
In `@js/__tests__/fixtures/test-data.ts`:
- Around line 74-78: The comment for createMinimalJpegBuffer is stale and the
function silently ignores its _width and _height parameters; update the comment
to state it returns a pre-encoded 16×16 JPEG (from REGULAR_JPEG_BASE64) and
explicitly document that the _width and _height args are ignored (or, if you can
change callers, remove the unused parameters and let callers call
base64ToArrayBuffer(REGULAR_JPEG_BASE64) directly); adjust the JSDoc/text in
createMinimalJpegBuffer and keep REGULAR_JPEG_BASE64 and base64ToArrayBuffer
references to make the intended fixed-size behavior clear.
---
Nitpick comments:
In `@wasm/package.json`:
- Line 48: Replace the no-op "test" script in wasm/package.json so it runs the
real JS tests: update the "test" script value to invoke the JS package test
runner (for example use "npm --prefix ../js test" or "npm --prefix ../js run
test") so running npm test in wasm/ actually executes and fails on test
failures; edit the "test" entry in package.json accordingly (look for the
existing "test" script key).
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
ℹ️ Review info
⚙️ Run configuration
Configuration used: Organization UI
Review profile: CHILL
Plan: Pro
Run ID: 73c344cb-3051-4990-bb6f-46e69040a488
⛔ Files ignored due to path filters (1)
package-lock.jsonis excluded by!**/package-lock.json
📒 Files selected for processing (42)
.github/workflows/ci.yml.github/workflows/npm-publish.yml.gitignore.gitmodulesLICENSELICENSE-APACHELICENSE-MITREADME.mdjs/README.mdjs/__tests__/encode.test.tsjs/__tests__/fixtures/test-data.tsjs/__tests__/integration.test.tsjs/__tests__/probe.test.tsjs/package.jsonjs/src/index.tspackage.jsonwasm/.npmignorewasm/CMakeLists.txtwasm/Cargo.tomlwasm/README.mdwasm/package.jsonwasm/pkg/open_ultrahdr.d.tswasm/rustfmt.tomlwasm/src/bindings.cppwasm/src/error.rswasm/src/gainmap/decode.rswasm/src/gainmap/encode.rswasm/src/gainmap/math.rswasm/src/gainmap/metadata.rswasm/src/gainmap/mod.rswasm/src/jpeg/mod.rswasm/src/jpeg/parser.rswasm/src/jpeg/writer.rswasm/src/jpeg/xmp.rswasm/src/jpeg_meta.cppwasm/src/jpeg_meta.hwasm/src/lib.rswasm/src/types.rswasm/src/ultrahdr/decoder.rswasm/src/ultrahdr/encoder.rswasm/src/ultrahdr/mod.rswasm/third_party/libultrahdr
💤 Files with no reviewable changes (18)
- wasm/src/jpeg/parser.rs
- wasm/rustfmt.toml
- wasm/src/gainmap/math.rs
- wasm/src/types.rs
- wasm/src/ultrahdr/mod.rs
- wasm/src/ultrahdr/encoder.rs
- wasm/src/jpeg/writer.rs
- wasm/.npmignore
- wasm/src/error.rs
- wasm/Cargo.toml
- wasm/src/gainmap/encode.rs
- wasm/src/gainmap/metadata.rs
- wasm/src/gainmap/mod.rs
- wasm/src/jpeg/mod.rs
- wasm/src/gainmap/decode.rs
- wasm/src/lib.rs
- wasm/src/ultrahdr/decoder.rs
- wasm/src/jpeg/xmp.rs
Comment on lines
+57
to
+64
| struct UltraHdrEncodeOptions { | ||
| int baseQuality = kDefaultBaseQuality; | ||
| int gainMapQuality = kDefaultGainMapQuality; | ||
| float targetHdrCapacity = kDefaultTargetHdrCapacity; | ||
| bool includeIsoMetadata = true; | ||
| bool includeUltrahdrV1 = true; | ||
| int gainMapScale = 1; | ||
| }; |
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includeIsoMetadata and includeUltrahdrV1 are silently ignored
These options are part of the public API (exposed in embind bindings and documented in TypeScript), but encodeUltraHdr() never reads them. Only baseQuality, gainMapQuality, gainMapScale, and targetHdrCapacity are used. Callers expecting these flags to control metadata emission will find them have no effect. Either wire them through to the underlying encoder or reject invalid configurations explicitly.
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@wasm/src/bindings.cpp` around lines 57 - 64, UltraHdrEncodeOptions contains
includeIsoMetadata and includeUltrahdrV1 but encodeUltraHdr() never uses them;
update encodeUltraHdr() to read these fields from UltraHdrEncodeOptions and
either (preferred) pass them into the underlying encoder/configuration API
(e.g., set equivalent flags on the encoder instance or encoder options used by
encodeUltraHdr()) so metadata emission respects includeIsoMetadata and
includeUltrahdrV1, or if the encoder cannot support them, validate and
return/throw an explicit error when those flags are set; locate
UltraHdrEncodeOptions and the encodeUltraHdr() implementation and wire these two
boolean flags into the encoder configuration or add validation logic to reject
unsupported combinations.
- ci.yml: pin Node via actions/setup-node@v4 in the wasm-build job. Without it the npm scripts ran on whatever Node ubuntu-latest happens to ship, which can drift silently. - js/src/index.ts: guard the WASM cache against stale in-flight inits. Previously, calling setLocation()/setWasmUrl() while a getWasm() was pending could let the older init publish to wasmInstance under the new config. Track an init generation; only the latest generation is allowed to set wasmInstance or clear initPromise. - js/src/index.ts: move getWasm() inside probeUltraHdr's try/catch so module-load failures degrade to the documented invalid-result fallback rather than escaping. - wasm/src/bindings.cpp + js/src/types.ts: document includeIsoMetadata and includeUltrahdrV1 as accepted-but-no-op for now. libultrahdr always emits both metadata blocks and exposes no public toggle; the fields stay in the API for stability with the prior Rust crate.
Owner
Author
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Thanks for the review. Pushed 3293169 addressing all four findings:
Re-ran locally: all 47 JS tests pass, lint + typecheck clean. |
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Closes #14.
Replaces the in-house Rust UltraHDR reimplementation with a thin Emscripten/embind C++ wrapper around upstream
google/libultrahdr, now that upstream is dual-licensedApache-2.0 OR MIT(google/libultrahdr#386) and can be redistributed freely.Why
The Rust crate existed because libultrahdr was Apache-2.0-only and we needed GPLv2 compatibility. With upstream now permissively dual-licensed, building on the canonical implementation gives us:
Apache-2.0 OR MITlicense for downstream consumers (notably WordPress/gutenberg#74873).What changed
wasm/src/bindings.cpp(~470 LoC) +jpeg_meta.cpp(~50 LoC)rustc+wasm-packemsdk+cmake+emccgoogle/libultrahdr@82b4f6da(git submodule)jpeg-decoder+jpeg-encodercrateslibjpegport (--use-port=libjpeg)GPL-2.0-or-laterApache-2.0 OR MITPublic JS API surface is unchanged — all exports keep the same names, signatures, and return shapes. Downstream consumers just bump the dep.
Verification
npm run build:wasmproduceswasm/pkg/open_ultrahdr.{js,wasm,d.ts}from a clean checkout (withemsdkactivated)npm test(JS) — 47/47 tests pass locally, exercising probe/decode/encode/extract/metadata/round-tripsnpm run typecheckclean (tsc --noEmit)npm run lint:jscleannpm run format:checkcleanTest fixture change
The legacy 2×2 JPEG fixture is replaced with a 16×16 fixture. libultrahdr enforces an 8×8 minimum dimension for spec-conformant gain map generation; the prior Rust crate's lax handling of tiny images was not spec-compliant. This is a test-only change — public API behavior is identical.
Migration phases (per #14)
pkg/open_ultrahdr.d.tsjs/src/index.tsto Emscripten factory +locateFileApache-2.0 OR MIT, bump to 0.2.0mymindstorm/setup-emsdk@v14Risks / notes
-Ozif it becomes an issue.crossOriginIsolatedrequirement). libultrahdr supports multi-threading; we accept the perf hit for deployment simplicity, revisit later.Float32Array(RGB, 3 floats/px). The C++ binding packs toUHDR_IMG_FMT_64bppRGBAHalfFloat(RGBA F16) before handing to libultrahdr.Commits
Summary by CodeRabbit