There used to be 2GB limitations both on JS typed arrays and on the size of wasm memory, so this might refer to either or both of those. But browsers have been

There used to be 2GB limitations both on JS typed arrays and on the size of wasm memory, so this might refer to either or both of those. But browsers have been fixing that, here is Chrome doing so back in 2020: https://v8.dev/blog/4gb-wasm-memory https://v8.dev/blog/4gb-wasm-memory (Note that as mentioned there you need to build the wasm with that support, like -sMAXIMUM_MEMORY=4GB in Emscripten, so ffmpeg.wasm would need that, if it hasn't added it already.)