for merge

flutter/web/js/src/codec.js

@@ -0,0 +1,43 @@
+// example: https://github.com/rgov/js-theora-decoder/blob/main/index.html
+// https://github.com/brion/ogv.js/releases, yarn add has no simd
+// dev: copy decoder files from node/ogv/dist/* to project dir
+// dist: .... to dist
+/*
+  OGVDemuxerOggW: 'ogv-demuxer-ogg-wasm.js',
+  OGVDemuxerWebMW: 'ogv-demuxer-webm-wasm.js',
+  OGVDecoderAudioOpusW: 'ogv-decoder-audio-opus-wasm.js',
+  OGVDecoderAudioVorbisW: 'ogv-decoder-audio-vorbis-wasm.js',
+  OGVDecoderVideoTheoraW: 'ogv-decoder-video-theora-wasm.js',
+  OGVDecoderVideoVP8W: 'ogv-decoder-video-vp8-wasm.js',
+  OGVDecoderVideoVP8MTW: 'ogv-decoder-video-vp8-mt-wasm.js',
+  OGVDecoderVideoVP9W: 'ogv-decoder-video-vp9-wasm.js',
+  OGVDecoderVideoVP9SIMDW: 'ogv-decoder-video-vp9-simd-wasm.js',
+  OGVDecoderVideoVP9MTW: 'ogv-decoder-video-vp9-mt-wasm.js',
+  OGVDecoderVideoVP9SIMDMTW: 'ogv-decoder-video-vp9-simd-mt-wasm.js',
+  OGVDecoderVideoAV1W: 'ogv-decoder-video-av1-wasm.js',
+  OGVDecoderVideoAV1SIMDW: 'ogv-decoder-video-av1-simd-wasm.js',
+  OGVDecoderVideoAV1MTW: 'ogv-decoder-video-av1-mt-wasm.js',
+  OGVDecoderVideoAV1SIMDMTW: 'ogv-decoder-video-av1-simd-mt-wasm.js',
+*/
+import { simd } from "wasm-feature-detect";
+
+export async function loadVp9(callback) {
+  // Multithreading is used only if `options.threading` is true. 
+  // This requires browser support for the new `SharedArrayBuffer` and `Atomics` APIs, 
+  // currently available in Firefox and Chrome with experimental flags enabled.
+  // 所有主流浏览器均默认于2018年1月5日禁用SharedArrayBuffer
+  const isSIMD = await simd();
+  console.log('isSIMD: ' + isSIMD);
+  window.OGVLoader.loadClass(
+    isSIMD ? "OGVDecoderVideoVP9SIMDW" : "OGVDecoderVideoVP9W",
+    (videoCodecClass) => {
+      window.videoCodecClass = videoCodecClass;
+      videoCodecClass({ videoFormat: {} }).then((decoder) => {
+        decoder.init(() => {
+          callback(decoder);
+        })
+      })
+    },
+    { worker: true, threading: true }
+  );
+}