samsung-wasm-decoder

Standalone H.264 video decoder for Samsung Tizen TVs using WASM EMSS (ElementaryMediaStreamSource) + a <video> element.

JS/TS API

This package exports:

• createSamsungWasmDecoder(options) – creates a WASM-backed decoder instance
• isSamsungWasmSupported() – checks WebAssembly + Samsung EMSS availability
• SamsungWasmDecoder (class)
• VideoDecoder (interface)
• ResultStatus (enum)

Rendering happens via a <video> element (default id: video-element).

Expected runtime

The TS wrapper expects an Emscripten module instance available as:

• window.SamsungWasmDecoderModule

The native module must export the C functions declared in native/decoder.cpp.

Build

Prerequisites

• Samsung customized Emscripten SDK (the one that provides Tizen WebAssembly extensions)
• Node.js (for TypeScript compilation)

Compile

# Build both native WASM and TypeScript
make build

This will:

1. Download Samsung's Emscripten SDK (if not present)
2. Compile the native C++ code to WASM
3. Compile the TypeScript wrapper

Outputs:

• dist/samsung-wasm-decoder.js – Emscripten-generated JS loader
• dist/samsung-wasm-decoder.wasm – WebAssembly module
• dist/index.js – TypeScript compiled wrapper

Build flags

The Makefile uses required flags for Samsung Tizen EMSS:

• -s ENVIRONMENT_MAY_BE_TIZEN – enables Samsung Tizen Emscripten extensions (required for EMSS)
• -pthread -s USE_PTHREADS=1 -s PTHREAD_POOL_SIZE=1 – EMSS requires pthreads support

Runtime loading

The native build is modularized (-s MODULARIZE=1 -s EXPORT_NAME=SamsungWasmDecoderModule). The generated samsung-wasm-decoder.js exports a factory function.

You must instantiate it and assign the resulting module instance to window.SamsungWasmDecoderModule before calling createSamsungWasmDecoder():

// Include the generated JS via <script> and then:
window.SamsungWasmDecoderModule = await SamsungWasmDecoderModule({});

After that:

import { createSamsungWasmDecoder } from '@signageos/samsung-wasm-decoder';

const decoder = createSamsungWasmDecoder({ videoElementId: 'video-element' });
await decoder.initialize({ width: 1920, height: 1080 });

// Feed Annex-B H.264 access units:
const decodeResult = await decoder.decodeAndRender(someNalAccessUnitArrayBuffer);
const flushResult = await decoder.flush();
await decoder.destroy();