I'm currently working on a streaming project, and I've come across WebAssembly (WASM) being mentioned as a solution for performance-heavy tasks like video processing. Can anyone explain when it's actually beneficial to use WASM for things like video transcoding, compared to just optimizing JavaScript?
2 Answers
Good point on existing C/C++ libraries! If you can utilize APIs like WebCodecs that are already optimized at a lower level, that might eliminate the need for WASM altogether. Compiling C/C++ to WASM offers significant advantages such as better numeric types and optimized memory structures, which can save a ton of hassle compared to using JavaScript.
Plus, WASM executes in the same runtime as JavaScript, and when you compare their performance, you’ll find that hardware-efficient JavaScript can be a nightmare to write. The availability of tried-and-true libraries like Ffmpeg in C makes it so much easier to compile rather than rewrite from scratch!
JavaScript can run quite fast in browsers, thanks to the powerful Just-In-Time (JIT) compilers. However, video processing poses unique challenges. For example, processing Full HD video means handling about 240 million bytes of data per second! While JavaScript can manage various tasks efficiently, it really struggles with this volume of data.
One reason to choose WASM is if you're rewriting the core algorithm in C. This typically speeds things up significantly because C allows for extensive low-level optimizations. Also, if you have existing video processing code in C, compiling it to WASM instead of rewriting it in JavaScript is often simpler and more reliable.
What do you think? Does that make sense?
Absolutely, it might even be more efficient to learn C and use Emscripten than to dive into the depths of JavaScript optimization for speed.