Multiple Clients Unable to Connect to Streaming Mountpoint Concurrently

General
1

I’m working on an application trying to implement Streaming Demo #3 (from: Janus WebRTC Server (multistream): Streaming Demo).

My process is:

  1. Creating a mountpoint through HTTP
  2. Using ffmpeg to stream to the mountpoint
  3. Connecting to the mountpoint from a front-end using websockets

Issue:
I can view the stream on my computer, but when someone else tries to connect while I’m connected, they receive no data.

I’m able to create a session with Janus through HTTP and create an RTP mountpoint with this as my POST body:

{
    "janus": "message", 
    "transaction": "transaction-id", 
    "body": {
        "admin_key": "supersecret", 
        "request": "create", 
        "type": "rtp",
        "id": 104, 
        "name": "My VideoSource", 
        "description": "TEST", 
        "is_private": false,
        "media": [
            {
                "type": "video",
                "mid": "video1",
                "port": 50161,
                "codec": "vp8",
                "payload_type": 100
            },
            {
                "type": "audio",
                "mid": "audio1",
                "port": 50162,
                "codec": "opus",
                "payload_type": 111
            }
        ],
        "permanent": false
    }
}

Ffmpeg is also able to stream from the source RTSP stream to the mountpoint. I’m just not able to view it concurrently from 2 computers. Any help would be appreciated. Here is the python script I use to stream:

def stream_video(rtsp_url, video_dst):
    cap = cv2.VideoCapture(rtsp_url)

    if not cap.isOpened():
        print("Error: Could not open the video stream.")
        return

    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
    input_fps = int(cap.get(cv2.CAP_PROP_FPS))

    print(f"Input FPS: {input_fps}")

    # ffmpeg input stream for video
    video_process = (
        ffmpeg
        .input('pipe:', format='rawvideo', pix_fmt='bgr24', s='{}x{}'.format(width, height), framerate=input_fps)
        .output(video_dst, vcodec='libvpx', deadline='realtime', format='rtp')
        .run_async(pipe_stdin=True)
    )

    frame_count = 0
    start_time = time.time()

    while True:
        ret, frame = cap.read()
        if not ret:
            print("Error: Could not read the frame.")
            break

        # Write the frame to the ffmpeg process
        video_process.stdin.write(frame.tobytes())
        frame_count += 1

        # Calculate and print output FPS every second
        elapsed_time = time.time() - start_time
        if elapsed_time >= 1.0:
            output_fps = frame_count / elapsed_time
            print(f"Output FPS: {output_fps:.2f}")
            frame_count = 0
            start_time = time.time()

    # Cleanup
    cap.release()
    video_process.stdin.close()
    video_process.wait()

I am capturing using opencv2 first because the stream has a much lower fps if I use ffmpeg to capture it directly.

Question
Is this due to an issue with how I am creating a mountpoint?
Is this an issue of how I am streaming my content to the mountpoint?
Or does everything here look fine and the issue may be somewhere else entirely?

Other posts I’ve checked out (sorry maxed out to links as a new user)
problem-viewing-existing-stream-on-multiple-clients-sessions

  • Unlike this user, I was trying to connect from multiple computers

unable-to-join-stream-missing-mandatory-element-feed

  • Looks like they were using the video room plugin instead. I’m also able to connect to the stream, it’s just that multiple people can’t.
2

Very likely they are receiving data, but they can’t display anything until a keyframe arrives. If you wait long enough that should happen. If you use the default demo you should see the bitrate indicator moving, which would confirm my theory. In that case, you can probably tweak FFmpeg to send keyframes more often (but I wouldn’t do it more often than every 5s).

3

Thank you Lorenzo for the support!

I wanted to update the thread because I found the source of my error. I initially started with changing my keyframe frequency, but that didn’t help me send concurrent streams.

When you said everything looks fine and I’m likely receiving data, it got me thinking that the data receiving was not the issue at all. I was getting an automatic “hangup” message from Janus for connections made after my initial successful one (ie. from another computer). Anyways, what I realized was that my RTP_PORT_RANGE was not configured correctly.

I thought RTP_PORT_RANGE was only present in janus.plugin.streaming.jcfg, but I realized it was also in janus.jcfg. I think at some point I must have edited either just one or both thinking that it was the same thing (careless cmd+F on my end). Anyways, this following post helped quite a bit:

Hopefully this helps people in the future!

1 Like