Initial implementation of mike and camera selection.

We're closing and reopening the connection each time, we should be
renegotiating instead.

static/sfu.css

@@ -49,6 +49,22 @@ h1 {
     display: none;
 }
 
+#optionsdiv {
+    margin-bottom: 4px;
+}
+
+#videoselect {
+    width: 8em;
+    text-align-last: center;
+    margin-right: 0.4em;
+}
+
+#audioselect {
+    width: 8em;
+    text-align-last: center;
+    margin-right: 0.4em;
+}
+
 #main {
     display: flex;
 }
@@ -111,6 +127,7 @@ h1 {
 }
 
 #input {
+    margin-left: 0.5em;
     width: 100%;
     border: none;
     resize: none;

static/sfu.html

@@ -31,8 +31,22 @@
       <div id="optionsdiv">
         <label for="presenterbox">Present:</label>
         <input id="presenterbox" type="checkbox"/ disabled>
+
+        <label for="videoselect">Camera:</label>
+        <select id="videoselect">
+          <option>default</option>
+          <option>off</option>
+        </select>
+
+        <label for="audioselect">Microphone:</label>
+        <select id="audioselect">
+          <option>default</option>
+          <option>off</option>
+        </select>
+
         <label for="sharebox">Share screen:</label>
         <input id="sharebox" type="checkbox"/ disabled>
+
       </div>
     </div>
 

static/sfu.js

@@ -126,6 +126,16 @@ document.getElementById('presenterbox').onchange = function(e) {
     setLocalMedia(this.checked);
 }
 
+document.getElementById('audioselect').onchange = function(e) {
+    e.preventDefault();
+    setLocalMedia(document.getElementById('presenterbox').checked);
+}
+
+document.getElementById('videoselect').onchange = function(e) {
+    e.preventDefault();
+    setLocalMedia(document.getElementById('presenterbox').checked);
+}
+
 document.getElementById('sharebox').onchange = function(e) {
     e.preventDefault();
     setShareMedia(this.checked);
@@ -193,6 +203,71 @@ function displayStats(id) {
         setLabel(id);
 }
 
+function mapMediaOption(value) {
+    console.assert(typeof(value) === 'string');
+    switch(value) {
+    case 'default':
+        return true;
+    case 'off':
+        return false;
+    default:
+        return value;
+    }
+}
+
+function addSelectOption(select, label, value) {
+    if(!value)
+        value = label;
+    for(let i = 0; i < select.children.length; i++) {
+        if(select.children[i].value === value) {
+            return;
+        }
+    }
+
+    let option = document.createElement('option');
+    option.value = value;
+    option.textContent = label;
+    select.appendChild(option);
+}
+
+// media names might not be available before we call getDisplayMedia.  So
+// we call this lazily.
+let mediaChoicesDone = false;
+
+async function setMediaChoices() {
+    if(mediaChoicesDone)
+        return;
+
+    let devices = [];
+    try {
+        devices = await navigator.mediaDevices.enumerateDevices();
+    } catch(e) {
+        console.error(e);
+        return;
+    }
+
+    let cn = 1, mn = 1;
+
+    devices.forEach(d => {
+        let label = d.label;
+        if(d.kind === 'videoinput') {
+            if(!label)
+                label = `Camera ${cn}`;
+            addSelectOption(document.getElementById('videoselect'),
+                            label, d.deviceId);
+            cn++;
+        } else if(d.kind === 'audioinput') {
+            if(!label)
+                label = `Microphone ${mn}`;
+            addSelectOption(document.getElementById('audioselect'),
+                            label, d.deviceId);
+            mn++;
+        }
+    });
+
+    mediaChoicesDone = true;
+}
+
 let localMediaId = null;
 
 async function setLocalMedia(setup) {
@@ -209,8 +284,14 @@ async function setLocalMedia(setup) {
         return;
     }
 
-    if(!localMediaId) {
-        let constraints = {audio: true, video: true};
+    let audio = mapMediaOption(document.getElementById('audioselect').value);
+    let video = mapMediaOption(document.getElementById('videoselect').value);
+
+    setLocalMedia(false);
+    if(!audio && !video)
+        return;
+
+    let constraints = {audio: audio, video: video};
     let stream = null;
     try {
         stream = await navigator.mediaDevices.getUserMedia(constraints);
@@ -220,8 +301,10 @@ async function setLocalMedia(setup) {
         await setLocalMedia(false);
         return;
     }
-        localMediaId = await newUpStream();
 
+    setMediaChoices();
+
+    localMediaId = await newUpStream();
     let c = up[localMediaId];
     c.stream = stream;
     stream.getTracks().forEach(t => {
@@ -234,7 +317,6 @@ async function setLocalMedia(setup) {
         displayStats(localMediaId);
     }, 2500);
     await setMedia(localMediaId);
-    }
 }
 
 let shareMediaId = null;