feat: add FFmpeg WASM runtime (#1512)

pkg/download/engine/inject/ffmpeg/ffmpeg.js

@@ -0,0 +1,139 @@
+(function () {
+  const create = __gopeed_ffmpeg_create;
+  const read = __gopeed_ffmpeg_read;
+  const acquire = __gopeed_ffmpeg_acquire;
+  const start = __gopeed_ffmpeg_start;
+  const push = __gopeed_ffmpeg_push;
+  const end = __gopeed_ffmpeg_end;
+  const cancel = __gopeed_ffmpeg_cancel;
+  const active = new Set();
+  globalThis.__gopeed_ffmpeg_close_all = () => {
+    for (const stop of Array.from(active)) stop(new Error("extension engine closed"));
+  };
+
+  function input(value, name, allowStream) {
+    if (value && typeof value.getReader === "function") {
+      if (!allowStream) throw new TypeError("stream inputs must be created by the inputs callback");
+      if (value.locked) throw new TypeError(name + " stream is locked");
+      return { stream: value, request: null };
+    }
+    if (!value || typeof value.url !== "string" || !/^https?:\/\//i.test(value.url)) {
+      throw new TypeError(name + " must be an HTTP request or ReadableStream");
+    }
+    const headers = {};
+    new Headers(value.headers || {}).forEach((v, k) => { headers[k] = v; });
+    return { request: { url: value.url, headers } };
+  }
+
+  function merge(options) {
+    if (!options || typeof options !== "object") throw new TypeError("merge options are required");
+    const factory = options.inputs;
+    if (factory !== undefined && typeof factory !== "function") throw new TypeError("inputs must be a callback");
+    if (factory && (options.video !== undefined || options.audio !== undefined)) throw new TypeError("inputs cannot be combined with video/audio");
+    let video = factory ? null : input(options.video, "video", false);
+    let audio = factory ? null : input(options.audio, "audio", false);
+    const args = options.args === undefined ? [] : options.args;
+    if (!Array.isArray(args) || args.some(v => typeof v !== "string")) throw new TypeError("args must be a string array");
+    const format = options.format === undefined ? "mp4" : options.format;
+    if (typeof format !== "string") throw new TypeError("format must be a string");
+    const signal = options.signal;
+    let id, controller, stopped = false;
+    const readers = [];
+    const lifetime = new AbortController();
+    let ownedInputs;
+    function discardInputs(inputs, reason) {
+      for (const source of new Set([inputs && inputs.video, inputs && inputs.audio])) {
+        if (source && typeof source.cancel === "function" && !source.locked) Promise.resolve(source.cancel(reason)).catch(() => {});
+      }
+    }
+
+    function stop(reason) {
+      if (stopped) return;
+      stopped = true;
+      active.delete(shutdown);
+      lifetime.abort();
+      discardInputs(ownedInputs, reason);
+      if (id) cancel(id);
+      if (signal) signal.removeEventListener("abort", abort);
+      for (const reader of readers) {
+        Promise.resolve(reader.cancel(reason)).catch(() => {}).then(() => {
+          try { reader.releaseLock(); } catch (_) {}
+        });
+      }
+    }
+    function shutdown(reason) {
+      controller.error(reason);
+      stop(reason);
+    }
+    function abort() {
+      const error = new Error("FFmpeg operation aborted");
+      error.name = "AbortError";
+      stop(error);
+      controller.error(error);
+    }
+    async function pump(reader, index) {
+      try {
+        while (!stopped) {
+          const result = await reader.read();
+          if (stopped) return;
+          if (result.done) { end(id, index, ""); return; }
+          if (!(result.value instanceof Uint8Array)) throw new TypeError("media streams must contain Uint8Array chunks");
+          // Keep individual crossings bounded, even if upstream emits a large chunk.
+          for (let offset = 0; offset < result.value.byteLength && !stopped; offset += 256 * 1024) {
+            if (!await push(id, index, result.value.subarray(offset, offset + 256 * 1024))) return;
+          }
+        }
+      } catch (error) {
+        if (!stopped) {
+          end(id, index, String(error && error.message || error));
+          controller.error(error);
+          stop(error);
+        }
+      }
+    }
+    return new ReadableStream({
+      start(c) {
+        controller = c;
+        active.add(shutdown);
+        if (signal) {
+          if (signal.aborted) abort();
+          else signal.addEventListener("abort", abort);
+        }
+      },
+      async pull(c) {
+        if (stopped) return;
+        try {
+          if (!id) {
+            id = create({ format, args });
+            await acquire(id);
+            if (stopped) return;
+            if (factory) {
+              const inputs = await factory({ signal: lifetime.signal });
+              if (stopped) { discardInputs(inputs, new Error("FFmpeg operation cancelled")); return; }
+              ownedInputs = inputs;
+              video = input(inputs && inputs.video, "video", true);
+              audio = input(inputs && inputs.audio, "audio", true);
+            }
+            if (video.stream && video.stream === audio.stream) throw new TypeError("video and audio must be distinct streams");
+            for (const source of [video, audio]) {
+              if (source.stream) readers.push(source.stream.getReader());
+            }
+            start(id, { video: video.request, audio: audio.request, format, args });
+            let readerIndex = 0;
+            for (const [index, source] of [video, audio].entries()) {
+              if (source.stream) void pump(readers[readerIndex++], index);
+            }
+          }
+          const chunk = await read(id);
+          if (stopped) return;
+          if (chunk === null) { stop(); c.close(); }
+          else c.enqueue(new Uint8Array(chunk));
+        } catch (error) {
+          if (!stopped) { c.error(error); stop(error); }
+        }
+      },
+      cancel(reason) { stop(reason); }
+    });
+  }
+  globalThis.__gopeed_ffmpeg = Object.freeze({ merge, supportsInputFactory: true });
+})();