How can I get native MediaStreamTrack from WebRtc MediaStreamTrackWeb object - dart

Question

I want to mix MediaStreamTrack objects in Dart using the package:universal_html/js.dart library.
JsAudioContext audioContext = JsAudioContext();
audioContext.initialize();
var senders = await call!.peerConnection!.getSenders();
for (var sender in senders) {
for (var track in senderTracks) {
if (sender.track!.id != track.id) {
audioContext.connect(track);
}
}
}
But WebRtc hides the jsTrack native object inside the MediaStreamTrackWeb object.
How can I access this object ?
Is there anyone have an idea ?

Answer 1

I found the solution using the js_bindings library.
The library's MediaStream.getTracks() method throws a type error.
I solved this problem using js_util interop.
JsAudioContext.dart:
import 'dart:convert';
import 'package:flutter_webrtc/flutter_webrtc.dart' as webrtc;
import 'package:dart_webrtc/src/media_stream_track_impl.dart' as track_impl;
import 'package:js_bindings/js_bindings.dart' as js_bindings;
import 'package:universal_html/html.dart' as html;
import 'dart:js_util' as js_util;
class JsAudioContext {
js_bindings.AudioContext? audioContext;
js_bindings.MediaStreamAudioDestinationNode? destinationNode;
JsAudioContext() {
audioContext = js_bindings.AudioContext();
}
void createMediaStreamDestination() {
destinationNode = audioContext?.createMediaStreamDestination();
}
void connect(webrtc.MediaStreamTrack? trackWeb) {
track_impl.MediaStreamTrackWeb mediaStreamTrackWeb =
trackWeb as track_impl.MediaStreamTrackWeb;
html.MediaStreamTrack htmlTrack = mediaStreamTrackWeb.jsTrack;
var sourceStream = audioContext?.createMediaStreamSource(
js_bindings.MediaStream([htmlTrack as js_bindings.MediaStreamTrack]));
sourceStream?.connect(destinationNode!);
}
webrtc.MediaStreamTrack getMixedTrack() {
List<dynamic> outputTrack =
js_util.callMethod(destinationNode!.stream, 'getTracks', []);
webrtc.MediaStreamTrack rtcTrack = track_impl.MediaStreamTrackWeb(
outputTrack.toList()[0] as html.MediaStreamTrack);
return rtcTrack;
}
}
sip_call_event_service.dart:
#override
Future startConference(List<SipCallData> activeCallList) async {
List<webrtc.MediaStreamTrack> receivedTracks = <webrtc.MediaStreamTrack>[];
for (var item in activeCallList) {
Call? call = sipuaHelper!.findCall(item.id!);
var receives = await call!.peerConnection!.getReceivers();
for (var element in receives) {
receivedTracks.add(element.track!);
}
}
JsAudioContext jsAudioContext = JsAudioContext();
for (var item in activeCallList) {
Call? call = sipuaHelper!.findCall(item.id!);
jsAudioContext.createMediaStreamDestination();
var receivers = await call!.peerConnection!.getReceivers();
for (var receiver in receivers) {
for (var track in receivedTracks) {
if (receiver.track!.id != track.id) {
jsAudioContext.connect(track);
}
}
}
var senders = await call.peerConnection!.getSenders();
for (var sender in senders) {
jsAudioContext.connect(sender.track);
}
await senders.first.replaceTrack(jsAudioContext.getMixedTrack());
}
}