Ice connection state stuck in checking

Hi!

I have been trying to work on handling frames from a wowza streaming server using python, i’m working since a while on this code and i cannot understand why my ice candidate still on checking state and i’m not receiving any frames or any feedback from server

I’m look for a lot of examples on this repository but i cannot reproduce the behavior on my code.

Here it’s my code.

import asyncio
import cv2
from aiortc import (
    RTCIceCandidate,
    MediaStreamTrack,
    RTCPeerConnection,
    RTCSessionDescription,
    RTCConfiguration,
)

pc = RTCPeerConnection(RTCConfiguration(iceServers=[]))


@pc.on("iceconnectionstatechange")
async def on_iceconnectionstatechange():
    print(f"ICE connection state is {pc.iceConnectionState}")
    if pc.iceConnectionState == "failed":
        await pc.close()
    if pc.iceConnectionState == "checking":
        candidates = pc.localDescription.sdp.split("\r\n")
        for candidate in candidates:
            if "a=candidate:" in candidate:
                print("added ice candidate")
                candidate = candidate.replace("a=candidate:", "")
                splitted_data = candidate.split(" ")
                remote_ice_candidate = RTCIceCandidate(
                    foundation=splitted_data[0],
                    component=splitted_data[1],
                    protocol=splitted_data[2],
                    priority=int(splitted_data[3]),
                    ip=splitted_data[4],
                    port=int(splitted_data[5]),
                    type=splitted_data[7],
                    sdpMid=0,
                    sdpMLineIndex=0,
                )
                pc.addIceCandidate(remote_ice_candidate)


@pc.on("track")
async def on_track(track):
    print(f"Track {track.kind} received")
    if track.kind == "video":
        local_video = VideoTransformTrack(track)
        pc.addTrack(local_video)
        await local_video.recv()

    @track.on("ended")
    def on_ended():
        print(f"Track {track.kind} ended")


@pc.on("datachannel")
async def on_datachannel(channel):
    print(f"changed datachannel to {channel}")


@pc.on("signalingstatechange")
async def on_signalingstatechange():
    print(f"changed signalingstatechange {pc.signalingState}")


@pc.on("icegatheringstatechange")
async def on_icegatheringstatechange():
    print(f"changed icegatheringstatechange {pc.iceGatheringState}")


class VideoTransformTrack(MediaStreamTrack):
    """
    A video stream track that transforms frames from an another track.
    """

    kind = "video"

    def __init__(self, track):
        super().__init__()  # don't forget this!
        self.track = track

    async def recv(self):
        print("trying to retrieve frame...")
        frame = await self.track.recv()
        print("framed retrieved.")
        return frame


async def offer(sdp, sdp_type):
    offer = RTCSessionDescription(sdp=sdp, type=sdp_type)
    # handle offer
    await pc.setRemoteDescription(offer)
    # send answer
    answer = await pc.createAnswer()
    await pc.setLocalDescription(answer)
    print("finished offer.")


if __name__ == "__main__":
    sdp_type = "offer"
    sdp = "v=0\r\no=WowzaStreamingEngine-next 948965951 2 IN IP4 127.0.0.1\r\ns=-\r\nt=0 0\r\na=fingerprint:sha-256 53:21:2B:54:27:E2:4F:16:7F:A9:70:0D:21:D0:0A:DF:9D:8A:E1:A7:6B:7B:A9:2B:57:D9:42:EB:C9:7A:76:8C\r\na=group:BUNDLE video\r\na=ice-options:trickle\r\na=msid-semantic:WMS *\r\nm=video 9 RTP/SAVPF 97\r\na=rtpmap:97 H264/90000\r\na=fmtp:97 packetization-mode=1;profile-level-id=42001f;sprop-parameter-sets=Z00AH52oFAFum4CAgKAAAAMAIAAAAwMQgA==,aO48gA==\r\na=cliprect:0,0,720,1280\r\na=framesize:97 1280-720\r\na=framerate:12.0\r\na=control:trackID=1\r\nc=IN IP4 0.0.0.0\r\na=sendrecv\r\na=ice-pwd:30f8917b33a334eb74fb468068b9b492\r\na=ice-ufrag:206f59a4\r\na=mid:video\r\na=msid:{af74b9ec-8e25-42a6-829c-ef935ac422c2} {4b9b5630-3b6b-41c9-9ca9-50bf00d7be78}\r\na=rtcp-fb:97 nack\r\na=rtcp-fb:97 nack pli\r\na=rtcp-fb:97 ccm fir\r\na=rtcp-mux\r\na=setup:actpass\r\na=ssrc:1715144048 cname:{a4361dd7-133c-4777-90dc-671394ecafe9}\r\n"
    loop = asyncio.get_event_loop()
    loop.run_until_complete(offer(sdp, sdp_type))
    loop.run_forever()

This is the output from the code.

Track video received
trying to retrieve frame...
changed signalingstatechange stable
changed signalingstatechange stable
changed icegatheringstatechange gathering
changed icegatheringstatechange complete
finished offer.
ICE connection state is checking
added ice candidate
added ice candidate
added ice candidate
added ice candidate
added ice candidate
added ice candidate

In this case the frame retrieved it’s never printed and the ICE connection state keeps in checking

Any feedback would be appreciated!

Cheers

Jcanabarro

[jlaine]

What exactly do you expect me to do with a hard-coded SDP blob?

[jcanabarro]

Well i’m always thought the forum was a guide, or at least some place we can share knowledge about related problems, i’m not here to say that the lib has some problems or something like that, no i’m just try to figure out what happens with my code, and why the have this behavior, maybe could be some problem with wowza or don’t know, maybe my code is really bad, you don’t need to answer my question if you never have this problem before, but maybe, just maybe has someone who has the same problem and figure out the solution. But this discussion will be useless and worthless.