Camera feed not showing up on QGC

[Apoorv-1009]

Hey everyone,

I have an RPI5, running Ubuntu 24, connected to a Pixhawk 6c running PX4 on TELEM2. I have 2 USB cameras connected to the RPI as well. When I launch mavlink-camera-manager, I am not able to get the camera feed on QGC. Infact, only one of my cameras shows up sometimes if I enter the RTSP URL in QGC, which I configure in :6020
Im trying to get camera switching working between the 2 cameras, but the feed does not even show up on QGC. Any direction on this would be sincerely appreciated.

Thank you
Apoorv Thapliyal

Im not sure if its relevant, but I have this stream of error logs:

2026-01-09T23:54:32.502737Z  WARN src/lib/logger/manager.rs:243: basesrc ../libs/gst/base/gstbasesrc.c:3177:gst_base_src_loop:<v4l2src2> error: streaming stopped, reason not-negotiated (-4)
2026-01-09T23:54:32.502845Z  WARN src/lib/stream/pipeline/runner.rs:70: task ended with error: "Some(\"Error from Some(\\\"/GstPipeline:pipeline-v4l2-f28fc077-0f66-54e3-a5ae-e61c7206518b/GstV4l2Src:v4l2src2\\\") for Pipeline \\\"pipeline-v4l2-f28fc077-0f66-54e3-a5ae-e61c7206518b\\\": Device '/dev/video0' is busy (Some(\\\"../sys/v4l2/gstv4l2object.c(4417): gst_v4l2_object_set_format_full (): /GstPipeline:pipeline-v4l2-f28fc077-0f66-54e3-a5ae-e61c7206518b/GstV4l2Src:v4l2src2:\\\\nCall to S_FMT failed for MJPG @ 1280x720: Device or resource busy\\\"))\")"
2026-01-09T23:54:32.503455Z  WARN src/lib/logger/manager.rs:243: v4l2 ../sys/v4l2/gstv4l2object.c:4725:gst_v4l2_object_set_crop:<v4l2src3:src> VIDIOC_S_CROP failed
2026-01-09T23:54:32.503546Z  WARN src/lib/logger/manager.rs:243: default ../sys/v4l2/v4l2-utils.c:189:gst_v4l2_error:<v4l2src3> error: Device '/dev/video2' is busy
2026-01-09T23:54:32.503581Z  WARN src/lib/logger/manager.rs:243: default ../sys/v4l2/v4l2-utils.c:192:gst_v4l2_error:<v4l2src3> error: Call to S_FMT failed for MJPG @ 1920x1080: Device or resource busy
2026-01-09T23:54:32.503689Z  WARN src/lib/logger/manager.rs:243: basesrc ../libs/gst/base/gstbasesrc.c:3397:gst_base_src_prepare_allocation:<v4l2src3> Subclass failed to decide allocation
2026-01-09T23:54:32.503736Z  WARN src/lib/logger/manager.rs:243: basesrc ../libs/gst/base/gstbasesrc.c:3177:gst_base_src_loop:<v4l2src3> error: Internal data stream error.
2026-01-09T23:54:32.503764Z  WARN src/lib/logger/manager.rs:243: basesrc ../libs/gst/base/gstbasesrc.c:3177:gst_base_src_loop:<v4l2src3> error: streaming stopped, reason not-negotiated (-4)
2026-01-09T23:54:32.503808Z  WARN src/lib/stream/pipeline/runner.rs:70: task ended with error: "Some(\"Error from Some(\\\"/GstPipeline:pipeline-v4l2-9215e7e1-9cf4-5ab6-86dd-e46a1b36a422/GstV4l2Src:v4l2src3\\\") for Pipeline \\\"pipeline-v4l2-9215e7e1-9cf4-5ab6-86dd-e46a1b36a422\\\": Device '/dev/video2' is busy (Some(\\\"../sys/v4l2/gstv4l2object.c(4417): gst_v4l2_object_set_format_full (): /GstPipeline:pipeline-v4l2-9215e7e1-9cf4-5ab6-86dd-e46a1b36a422/GstV4l2Src:v4l2src3:\\\\nCall to S_FMT failed for MJPG @ 1920x1080: Device or resource busy\\\"))\")"
2026-01-09T23:54:33.419772Z ERROR src/lib/mavlink/manager.rs:244: Failed to connect, trying again in one second. Reason: Os { code: 98, kind: AddrInUse, message: "Address already in use" }.
^C2026-01-09T23:54:33.983918Z  INFO /home/apoorv/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/actix-server-2.6.0/src/server.rs:333: SIGINT received; starting forced shutdown
2026-01-09T23:54:33.984059Z  INFO /home/apoorv/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/actix-server-2.6.0/src/worker.rs:593: shutting down idle worker
2026-01-09T23:54:33.984189Z  INFO /home/apoorv/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/actix-server-2.6.0/src/accept.rs:143: accept thread stopped
2026-01-09T23:54:34.286556Z  WARN src/lib/logger/manager.rs:243: shmsink ../sys/shm/gstshmsink.c:842:pollthread_func:<shmsink2> error: Failed waiting on fd activity
2026-01-09T23:54:34.286556Z  WARN src/lib/logger/manager.rs:243: shmsink ../sys/shm/gstshmsink.c:842:pollthread_func:<shmsink3> error: Failed waiting on fd activity
2026-01-09T23:54:34.286646Z  WARN src/lib/logger/manager.rs:243: shmsink ../sys/shm/gstshmsink.c:842:pollthread_func:<shmsink2> error: gst_poll_wait returned -1, errno: 16
2026-01-09T23:54:34.286657Z  WARN src/lib/logger/manager.rs:243: shmsink ../sys/shm/gstshmsink.c:842:pollthread_func:<shmsink3> error: gst_poll_wait returned -1, errno: 16

[joaoantoniocardoso]

Hi, welcome!

There might be multiple problems going on. For instance, the logs show:

1. The GStreamer element v4l2src is failing to access the Linux device because it's busy; it can be that somehow MCM itself didn't free the resource properly in a previous attempt, or it can be another software accessing it.
2. MCM is not able to connect to the configured MAVLink address because it's in use by another software (or somehow MCM itself in a previous attempt).

To help you further, can you:

1. Check whether there are multiple instances of MCM running on the same host/Linux
2. Paste here the command line you are using for MCM
3. Paste here the config file (it's ~/.config/mavlink-camera-manager/settings.json unless your commandline set it differently)
4. What software are you using as the MAVLink router, and how is it being configured?
5. What is the network topology in terms of each device's IP address on the network?

Thanks

[Apoorv-1009]

Thanks for your prompt reply

1. So for MCM, heres how I know theres no extra instances running:

ps aux | grep [m]avlink-camera-manager
apoorv      2694  0.0  0.0   9280  1792 pts/0    S+   20:24   0:00 grep --color=auto mavlink-camera-manager

2. I run mcm simply with: ./mavlink-camera-manager-aarch64, this brings up one camera stream when I put the RTSP URL into QGC, but only sometimes
3. Here is my settings.json:

apoorv@apoorv-desktop:~$ cat ~/.config/mavlink-camera-manager/settings.json
{
  "header": {
    "name": "Camera Manager",
    "version": 0
  },
  "mavlink_endpoint": "udpin:0.0.0.0:14550",
  "streams": [
    {
      "name": "/dev/video2 - FHD Camera Microphone: FHD Came",
      "stream_information": {
        "endpoints": [
          "rtsp://192.168.1.52:8554/cam1"
        ],
        "configuration": {
          "type": "video",
          "encode": "MJPG",
          "height": 1080,
          "width": 1920,
          "frame_interval": {
            "numerator": 1,
            "denominator": 30
          }
        },
        "extended_configuration": {
          "thermal": false,
          "disable_mavlink": false,
          "disable_zenoh": false,
          "disable_thumbnails": false
        }
      },
      "video_source": {
        "Local": {
          "name": "FHD Camera Microphone: FHD Came",
          "device_path": "/dev/video2",
          "type": {
            "Unknown": "usb-xhci-hcd.0-2"
          }
        }
      }
    },
    {
      "name": "/dev/video0 - USB 2.0 Camera: HD USB Camera",
      "stream_information": {
        "endpoints": [
          "rtsp://192.168.1.52:8554/cam2"
        ],
        "configuration": {
          "type": "video",
          "encode": "MJPG",
          "height": 720,
          "width": 1280,
          "frame_interval": {
            "numerator": 1,
            "denominator": 30
          }
        },
        "extended_configuration": {
          "thermal": false,
          "disable_mavlink": false,
          "disable_zenoh": false,
          "disable_thumbnails": false
        }
      },
      "video_source": {
        "Local": {
          "name": "USB 2.0 Camera: HD USB Camera",
          "device_path": "/dev/video0",
          "type": {
            "Unknown": "usb-xhci-hcd.1-1"
          }
        }
      }
    }
  ]
}

4. I installed mavlink-routerd-glibc-aarch64 from the github release, v4. I run it like so: ./mavlink-routerd-glibc-aarch6 -c mavlink_router.conf. Here is my mavlink_router.conf file:

cat mavlink_router.conf
[General]
MavlinkDialect=auto
ReportStats=false
Log=false

# PX4 serial input
[UartEndpoint px4]
Device=/dev/ttyAMA0
Baud=57600

# QGC endpoint (my laptop)
[UdpEndpoint qgc]
Address=192.168.1.12
Port=14550
Mode=Normal

# Camera server (For any custom program I may write)
[UdpEndpoint camera]
Address=127.0.0.1
Port=14540
Mode=Normal

6. The following is the topology:

• I have a windows laptop with IP: 192.168.1.12, which has my QGC
• My RPI5 has IP: 192.168.1.52
• Both my cameras are connected via usb and are discoverable via v4l2-ctl --list-devices (output below)

FHD Camera Microphone: FHD Came (usb-xhci-hcd.0-2):
        /dev/video2
        /dev/video3
        /dev/media4

USB 2.0 Camera: HD USB Camera (usb-xhci-hcd.1-1):
        /dev/video0
        /dev/video1
        /dev/media3

• My Pixhawk is connected via serial, on /dev/ttyAMA0

Thank you

[joaoantoniocardoso]

Thanks for the info, I believe you need to either switch to TCP for MCM, or use mavlink-server instead.

This happens because the router you are using tries to be smart and apply filters based on component ID, and MCM is multiple components, so it gets confused.

Can you try and tell me how it goes?

Thanks!

[Apoorv-1009]

May I know how to switch to TCP with mcm? I understand that there is this command is there in the README: mavlink-camera-manager --mavlink=tcpout:0.0.0.0:14000 --verbose
I tried this too but it did not work
For mavlink server, what would the command be to connect this mavlink camera manager to mavlink server and QGC? Basically I am trying to understand the command required to get it working on my setup and if theres any specific config needed

Thank you

[Apoorv-1009]

Heres how I ran the mavlink server:
Started mavlink server with: ./mavlink-server-aarch64-unknown-linux-musl serial:/dev/ttyAMA0:57600 udpserver://0.0.0.0:14550
Started mavlink camera server with: ./mavlink-camera-manager-aarch64
On QGC, I was able to connect to the RPI by simply adding a comm link at 192.168.1.52:14550
However the camera feed is still not visible

Is it possible that the newer Raspberry Pi OS removed the GStreamer element that mavlink-camera-manager relies on?
It could be that the mavlink-camera-manager hasn’t been updated yet to use libcamera, which replaced the older GStreamer-based camera stack.

Appreciate your support

[joaoantoniocardoso]

Hi,

Is it possible that the newer Raspberry Pi OS removed the GStreamer element that mavlink-camera-manager relies on?

Which version of libcamera and QGC are shipped with your Raspberry Pi OS?

You can also run mavlink-camera-manager within a container, just like this example. I'd give it a try if you think GStreamer/libcamera versions can be mismatched to what MCM is expecting.

---

About your setup, here's some more help. Keep in mind that I didn't have the time to test this exact setup, but I gathered commands from my personal notes:

The following commands set:

• UDP server at 14550 (for QGC);
• TCP server at 5777 (for MCM);
• your serial;

mavlink-server \
  serial:/dev/ttyAMA0:57600 \
  udpserver:127.0.0.1:14550 \
  tcpserver:127.0.0.1:5777 \
  --verbose

and then:

• set MCM to connect to that TCP server at 5777;
• to be compatible with QGC with multiple cameras, set cameras component ID to range from 100 to 105;

Note: the --reset parameter is needed here just to be sure we don't load previous configurations. Once you are good with the configs, drop it from the command line.

mavlink-camera-manager \
  --mavlink tcpout:127.0.0.1:5777 \
  --mavlink-system-id 1 \
  --mavlink-camera-component-id-range 100-105 \
  --verbose \
  --reset

When testing MCM with QGC, I first remove all settings -- it keeps some cache about camera and MAVLink that makes testing very inconsistent. Feel free to back up the folders before removing them if you care about your QGC configs:

rm -rf \
  ~/.cache/QGroundControl.org \
  ~/.cache/QGCMapCache300 \
  ~/.config/QGroundControl.org \
  ~/Documents/QGroundControl

Then, I open QGC (appimage version).

---

I hope it helps. Let me know if you need more guidance to make it work, thanks!