Split MediaViewModel into multiple files

src/state/media/observeSpeaker.ts

@@ -0,0 +1,36 @@
+/*
+Copyright 2024 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+import {
+  type Observable,
+  audit,
+  merge,
+  timer,
+  filter,
+  startWith,
+  distinctUntilChanged,
+} from "rxjs";
+
+/**
+ * Require 1 second of continuous speaking to become a speaker, and 60 second of
+ * continuous silence to stop being considered a speaker
+ */
+export function observeSpeaker$(
+  isSpeakingObservable$: Observable<boolean>,
+): Observable<boolean> {
+  const distinct$ = isSpeakingObservable$.pipe(distinctUntilChanged());
+
+  return distinct$.pipe(
+    // Either change to the new value after the timer or re-emit the same value if it toggles back
+    // (audit will return the latest (toggled back) value) before the timeout.
+    audit((s) =>
+      merge(timer(s ? 1000 : 60000), distinct$.pipe(filter((s1) => s1 !== s))),
+    ),
+    // Filter the re-emissions (marked as: | ) that happen if we toggle quickly (<1s) from false->true->false|->..
+    startWith(false),
+    distinctUntilChanged(),
+  );
+}