From eea8b1acce67a85e9dfbeb992e21a26480bd9b5e Mon Sep 17 00:00:00 2001
From: James Ketrenos <james_eikona@ketrenos.com>
Date: Sat, 19 Mar 2022 10:24:39 -0700
Subject: [PATCH] Added dummy audio/video track if no media access

Signed-off-by: James Ketrenos <james_eikona@ketrenos.com>
---
 client/src/MediaControl.js | 107 +++++++++++++++++++++++++++++--------
 1 file changed, 86 insertions(+), 21 deletions(-)

diff --git a/client/src/MediaControl.js b/client/src/MediaControl.js
index ec97634..8ccf159 100644
--- a/client/src/MediaControl.js
+++ b/client/src/MediaControl.js
@@ -392,37 +392,102 @@ const MediaAgent = ({setPeers}) => {
         * attach it to an <audio> or <video> tag if they give us access. */
       console.log("media-agent - Requesting access to local audio / video inputs");
   
+      /* See Dummy Tracks for more ideas...
+      https://blog.mozilla.org/webrtc/warm-up-with-replacetrack/
+      */
       navigator.getUserMedia = (navigator.getUserMedia ||
         navigator.webkitGetUserMedia ||
         navigator.mozGetUserMedia ||
         navigator.msGetUserMedia);
   
       return navigator.mediaDevices
-        .getUserMedia({audio: true, video: true})
+      .getUserMedia({audio: true, video: true})
+      .then((media) => {
+        return {
+          media: media,
+          audio: true,
+          video: true
+        };
+      })
       .catch((error) => {
-        console.log(`media-agent - Access granted to audio and video ` +
+        console.log(`media-agent - Access to audio and video ` +
           `failed. Trying just audio.`);
         return navigator.mediaDevices
-          .getUserMedia({ audio: true, video: false })
-      })
-      .then((media) => { /* user accepted access to a/v */
-        console.log("media-agent - Access granted to audio/video");
-        media.getVideoTracks().forEach((track) => {
-          track.applyConstraints({
-            "video": {
-              "width": {
-                "min": 160,
-                "max": 320
-              },
-              "height": {
-                "min": 120,
-                "max": 240
-              } 
-            }
-          });
+        .getUserMedia({ audio: true, video: false })
+        .then((media) => {
+          return {
+            media: media,
+            audio: true,
+            video: false
+          };
+        })
+        .catch((error) => {
+          console.log(`media-agent - Access to audio ` +
+            `failed.`);
+          return {
+            media: undefined,
+            audio: false,
+            video: false
+          };
         });
+      })
+      .then((context) => { /* user accepted access to a/v */
+        if (context.video) {
+          console.log("media-agent - Access granted to audio/video");
+          context.media.getVideoTracks().forEach((track) => {
+            track.applyConstraints({
+              "video": {
+                "width": {
+                  "min": 160,
+                  "max": 320
+                },
+                "height": {
+                  "min": 120,
+                  "max": 240
+                } 
+              }
+            });
+          });
+          return context.media;
+        }
 
-        return media;
+        const black = ({ width = 640, height = 480 } = {}) => {
+          const canvas = Object.assign(document.createElement("canvas"), {
+            width, height
+          });
+          canvas.getContext('2d').fillRect(0, 0, width, height);
+          const stream = canvas.captureStream();
+          return Object.assign(stream.getVideoTracks()[0], {
+            enabled: true
+          });
+        }
+
+        const silence = () => {
+          const ctx = new AudioContext(), oscillator = ctx.createOscillator();
+          const dst = oscillator.connect(ctx.createMediaStreamDestination());
+          oscillator.start();
+          return Object.assign(dst.stream.getAudioTracks()[0], {
+            enabled: true
+          });
+        }
+
+        if (context.audio) {
+          console.log("media-agent - Access granted to audio");
+
+          let black = ({ width = 640, height = 480 } = {}) => {
+            let canvas = Object.assign(document.createElement("canvas"), {
+              width, height
+            });
+            canvas.getContext('2d').fillRect(0, 0, width, height);
+            let stream = canvas.captureStream();
+            return Object.assign(stream.getVideoTracks()[0], {
+              enabled: true
+            });
+          }
+          return new MediaStream([context.media, black()]);
+        }
+
+        return new MediaStream([black(), silence()]);
       });
     };
   
@@ -431,7 +496,7 @@ const MediaAgent = ({setPeers}) => {
       if (debug) console.log(`media-agent - WebSocket open request. Attempting to create local media.`);
       setup_local_media().then((media) => {
         /* once the user has given us access to their
-        * microphone/camcorder, join the channel and start peering up */
+         * microphone/camcorder, join the channel and start peering up */
         if (abort) {
           console.log(`media-agent - aborting setting local media`);
         } else {