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Linux Camera Systems

Cameras in Linux are seen as /dev/video*. They have different output formats and resolutions. To check the available formats, use the following command:

v4l2-ctl -d /dev/video0 --list-formats-ext

after the camera static link setup is best to use:

v4l2-ctl -d /dev/camera-main --list-formats-ext

also to check that the ATTR{index} is set up correctly.

Camera Formats Explained

The formats can be MJPG or H264:

  • MJPG (Motion JPEG): A series of JPEG images sent in sequence.

    • Pros: Higher quality, widely supported
    • Cons: Higher bandwidth usage, must be transcoded for efficient streaming
    • Must be encoded to H264 for efficient network streaming
    • May introduce lag on the client side due to decoding overhead
    • To stream in MJPG use ustreamer, easy to set up and easy to work with, also with the snapshots

  • H264: A compressed video format

    • Pros: Already compressed, lower bandwidth, ready for Real-Time Communication (RTC)
    • Cons: May have slightly lower quality than MJPG at the same bitrate
    • DWE cameras can output compressed H264 natively and are streamed directly with DWE OS 2

Camera Identification

To understand which camera is associated with a specific /dev/video*, use the following command:

v4l2-ctl --list-devices

This script will list all video devices and their corresponding camera models/types.