页面交互后，打开摄像头，加延迟。

src/features/OnlineExam/Examing/ExamingHome.vue

@@ -21,7 +21,7 @@
       <div :class="['question-nav']">
         <QuestionNavView :paper-struct="paperStruct" />
       </div>
-      <div v-if="faceEnable" class="camera">
+      <div v-if="faceEnable && startVideoAfterDelay" class="camera">
         <FaceRecognition
           v-if="faceEnable"
           width="400"
@@ -83,6 +83,7 @@ export default {
       showFaceId: false,
       faceEnable: false,
       timeouted: false,
+      startVideoAfterDelay: false,
       PRODUCTION: process.env.NODE_ENV === "production",
     };
   },
@@ -256,7 +257,7 @@ export default {
         } else {
           initSnapshotTrialTimes++;
         }
-      }, 15 * 1000);
+      }, 20 * 1000);
 
       //       let initSnapshotTrialTimes = 0;
       // const initSnapshot = setTimeout(() => {
@@ -320,6 +321,11 @@ export default {
     // 避免macos上下塘动。避免产生滚动条。
     document.body.classList.toggle("hide-body-scroll", true);
 
+    // NotAllowedError: play() failed because the user didn't interact with the document first. https://goo.gl/xX8pDD
+    this.startVideoAfterDelayTimeout = setTimeout(() => {
+      this.startVideoAfterDelay = true;
+    }, 10 * 1000);
+
     window._hmt.push(["_trackEvent", "正在考试页面", "进入页面"]);
 
     if (typeof nodeRequire != "undefined") {
@@ -364,6 +370,7 @@ export default {
     clearInterval(this.snapInterval);
     clearTimeout(this.faceIdMsgTimeout);
     clearTimeout(this.faceIdDivTimeout);
+    clearTimeout(this.startVideoAfterDelayTimeout);
     closeWsWithoutReconnect();
     this.updateExamState({
       exam: null,