add default mimeType if none is specified

Author: jadeddelta

.changeset/sixty-ears-tan.md

@@ -0,0 +1,5 @@
+---
+"jspsych": patch
+---
+
+add a default `mimeType` of `"video/webm" to `initializeCameraRecorder()`

docs/reference/jspsych-pluginAPI.md

@@ -507,8 +507,7 @@ None.
 
 #### Description
 
-Generates a `MediaRecorder` object from provided `MediaStream` and stores this for access via [`getCameraRecorder()`](#getcamerarecorder).
-
+Generates a `MediaRecorder` object from provided `MediaStream` and stores this for access via [`getCameraRecorder()`](#getcamerarecorder). By default, `mimeType` is set to `"video/webm"`.
 #### Example
 
 ```javascript

examples/extension-record-video.html

@@ -13,7 +13,10 @@
     const jsPsych = initJsPsych({
         extensions: [
             {type: jsPsychExtensionRecordVideo}
-        ]
+        ],
+        on_finish: function() {
+          jsPsych.data.displayData();
+        }
     });
 
     const initCamera = {

packages/jspsych/src/modules/plugin-api/MediaAPI.ts

@@ -284,6 +284,12 @@ export class MediaAPI {
   private camera_recorder: MediaRecorder = null;
 
   initializeCameraRecorder(stream: MediaStream, opts?: MediaRecorderOptions) {
+    if (!opts) {
+      opts = { mimeType: "video/webm" };
+    } else if (!opts.mimeType) {
+      opts.mimeType = "video/webm";
+    }
+
     this.camera_stream = stream;
     const recorder = new MediaRecorder(stream, opts);
     this.camera_recorder = recorder;