Open Media Transport (OMT) Encoder for Raspberry Pi 5

omtcapture is an encoder for Raspberry Pi 5 which converts USB 3.0 based video capture devices including Webcams to an Open Media Transport (OMT) source on the network.

Requirements

• Raspberry Pi 5 with default OS installed. 2GB memory option is fine.
• USB 3.0 UVC capture device that supports uncompressed video in either UYVY, YUY2 or NV12 formats (examples include Elgato Cam Link, Magewell USB Capture, Elgato Facecam series etc)
• dotnet 8
• Clang
• libomtnet
• libvmx

Performance

A base model 2GB Raspberry Pi 5 can comfortably encode at up to 1080p60

Instructions

It is recommended to update the Raspberry Pi package manager before proceeding further:

sudo apt update

1. Install dotnet 8 on to device.

curl -sSL https://dot.net/v1/dotnet-install.sh | bash /dev/stdin --channel 8.0

echo 'export DOTNET_ROOT=$HOME/.dotnet' >> ~/.bashrc
echo 'export PATH=$PATH:$HOME/.dotnet' >> ~/.bashrc
source ~/.bashrc

For reference, the latest instructions that include the above commands are below: https://learn.microsoft.com/en-us/dotnet/iot/deployment

Important: The --channel parameter should be set to 8.0

2. Install Clang

sudo apt install clang

3. Copy source code for the following repositories into the home directory in a structure similar to the following:

~/libvmx
~/libomtnet
~/omtcapture

The easiest way to do this is to git clone these repositories to the home directory using the commands below:

cd ~/
git clone https://github.com/openmediatransport/libvmx
git clone https://github.com/openmediatransport/libomtnet
git clone https://github.com/openmediatransport/omtcapture

4. Build libvmx

cd ~/libvmx/build
chmod 755 buildlinuxarm64.sh
./buildlinuxarm64.sh

5. Build libomtnet

cd ~/libomtnet/build
chmod 755 buildall.sh
./buildall.sh

6. Build omtcapture

cd ~/omtcapture/build
chmod 755 buildlinuxarm64.sh
./buildlinuxarm64.sh

7. All files needed will now be in ~/omtcapture/build/arm64

8. Edit the config file in ~/omtcapture/build/arm64/config.xml to match the desired capture format.

nano ~/omtcapture/build/arm64/config.xml

You may need to check the capture device documentation to confirm the maximum format that supports uncompressed video. (Many devices may restrict high frame rates to MJPG only for example)

An example that finds the first device on the system and encodes at 1080p59.94 is below.

If the device does not support the selected frame rate, the nearest will be used instead.

<?xml version="1.0" encoding="utf-8" ?>
<settings>
  <name>Video</name>
  <!--V4L2 Device Path-->
  <devicePath>/dev/video0</devicePath>
  <width>1920</width>
  <height>1080</height>
  <frameRateN>60000</frameRateN>
  <frameRateD>1001</frameRateD>
  <!--Supported Formats: UYVY, YUY2, NV12-->
  <codec>UYVY</codec>
</settings>

9. Run ~/omtcapture/build/arm64/omtcapture to start the encoding. The source should now be on the network.

~/omtcapture/build/arm64/omtcapture

Install as a service (optional)

This configures the app to run automatically when the device starts up.

1. Copy the omtcapture files from ~/omtcapture/build/arm64 into a folder called /opt/omtcapture on the system.

sudo mkdir /opt/omtcapture
sudo cp ~/omtcapture/build/arm64/* /opt/omtcapture/

2. Copy the omtcapture.service template into the /etc/systemd/system/ folder.

sudo cp ~/omtcapture/omtcapture.service /etc/systemd/system/

3. Reload systemctl and enable the service

sudo systemctl daemon-reload
sudo systemctl enable omtcapture

4. Start the service and check its status

sudo systemctl start omtcapture
sudo systemctl status omtcapture

If successful, the output should show a log entry every 60 frames to confirm encoding is in process.