datachannel has a great latency

My Code

https://github.com/tsonglew/aiortc-datachannel-delay

run python main.py to start the server, then visit localhost:8080 with a web browser

My Problem

I’m trying to process the video frames from video track, and send back the result with datachannel.

the result is replaced with time.time() in the above demo repo as following:

self.channel.send(
      json.dumps({"now": time.time() * 1000})
)

the <client receive from datachannel time> - <datachennl.send() time> is considered as delay, and are console.loged with code:

ch.addEventListener("message", function (evt) {
	console.log(Date.now() - JSON.parse(evt.data).now);
});

the datachannel config is {ordered: false, maxRetransmits: 0}

Output

as illustrated in the sreenshot, the delay is growing, but video and audio are fluent.

How can I get rid of the growing delay? Thx

[tsonglew]

as a workaround, I altered my datachannel sending code like this

self.channel.send(json.dumps({"now": time.time() * 1000}))
await self.channel._RTCDataChannel__transport._data_channel_flush()
await self.channel._RTCDataChannel__transport._transmit()

[Interpause]

Could above be implemented as a option when creating a data channel?