Fix microphone issues with Firefox and Safari (#233)

* Firefox can't open more than one microphone per process. When
  switching audio input device, we need to stop using current device
before opening new one. This also somewhat affect safari, causing "A
MediaStreamTrack ended due to a capture failure" error.

* Remove overriding preffered codec profile with default.

src/stream.ts

@@ -253,10 +253,6 @@ export class LocalStream extends MediaStream {
       const cap = RTCRtpSender.getCapabilities(kind);
       if (!cap) return;
       let selCodec: RTCRtpCodecCapability | undefined;
-      // 42e01f for safari/chrome/firefox cross-browser compatibility
-      if (kind === 'video' && this.constraints.codec && this.constraints.codec.toLowerCase() === 'h264') {
-        this.constraints.preferredCodecProfile = '42e01f'
-      }
       if (this.constraints.preferredCodecProfile && kind === 'video') {
         const allCodecProfiles = cap.codecs.filter(
           (c) => c.mimeType.toLowerCase() === `video/${this.constraints.codec.toLowerCase()}`,
@@ -302,8 +298,6 @@ export class LocalStream extends MediaStream {
         });
       }
     } else {
-      this.addTrack(next);
-
       if (this.pc) {
         this.publishTrack(next);
       }
@@ -359,6 +353,8 @@ export class LocalStream extends MediaStream {
     };
 
     const prev = this.getTrack(kind);
+    // Firefox/Safari have issues when multiple input devices are used by same origin. We need to stop previous track before creating new one.
+    if (prev) prev.stop()
     const next = await this.getNewTrack(kind);
 
     this.updateTrack(next, prev);