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TN015:
Obtaining the lowest latency from your
Harrier AF-Zoom IP camera
Summary
This Technical Note introduces IP cameras and the latency
associated with IP video transmission; it also explains how to
achieve the lowest latency from a Harrier AF-Zoom IP camera or
Harrier IP Camera Interface Board, and what rates can be
expected. With some Harrier cameras, latency can be as low as
140ms, however many factors will affect this, including the
network configuration and type of PC used.
Background
An IP (Internet Protocol) camera is a digital camera that transmits and receives data over a network or the
internet. An IP camera uses its own IP address to connect to a network and doesn't rely on a connection
to a PC or alternative host device. IP cameras capture images, compress them (usually using H.264 or
H.265 encoders) and then transmit them over an Ethernet network, commonly in the form of streaming
real-time video. They may be used with a wired network (connected via an Ethernet cable to a
switch/router/PC), or wirelessly (via a WiFi router/access point).
Controlling Harrier AF-Zoom IP cameras is straightforward. As they are ONVIF Profile S compatible, user
developed applications, or any Profile S-based third-party software, can easily control the camera. Harrier
AF-Zoom IP cameras also offer a wide range of other advanced camera features (e.g. day/night
functionality, optical zoom, WDR, etc.) that can all be controlled remotely. In addition, the IP video stream
is available in three different profiles, each with different video compression settings.
Understanding latency
For the purpose of this Technical Note, latency is defined as the delay from when an image is captured by
the camera lens to when it is observable on a video display (glass to glass). Variability in latency is
referred to as jitter, so a system with high variation in latency will have high jitter.
Image capture and video data transmission will always be subject to latency because of the unavoidable
acquisition, transport and processing delays between various system components. Latency in vision
systems is typically recorded in milliseconds (ms).
The level of acceptable latency within a vision system depends on the application. For example, an ANPR
parking system can tolerate high latency as there is no short critical time requirement in the application.
However, a moving remote-operated robot or vehicle requires the lowest latency possible so that the
Version 2.04 July 2024
TECHNICAL NOTE 015
Figure 1. Harrier 10x AF-Zoom IP/HDMI
Camera (Tamron MP3010M-EV)
Page 1 of 9
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Summary of Contents for Active Silicon TN015
- Page 1 TECHNICAL NOTE 015 TN015: Obtaining the lowest latency from your Harrier AF-Zoom IP camera Summary This Technical Note introduces IP cameras and the latency associated with IP video transmission; it also explains how to achieve the lowest latency from a Harrier AF-Zoom IP camera or Harrier IP Camera Interface Board, and what rates can be expected.
- Page 2 TECHNICAL NOTE 015 operator can respond quickly to the changes in the environment with minimal delay; a slow response time can result in inefficient operation and even damage to the vehicle or other nearby objects. Human perception also plays a part in determining if latency levels are acceptable – anything taking longer than 200-300ms tends to feel sluggish and awkward to control, so ideally a real-time user- controlled system will aim for less than this.
- Page 3 TECHNICAL NOTE 015 The Harrier IP Camera Interface Board receives the image data from the camera module and can perform additional image processing such as the addition of overlays or image scaling. The images are then H.264 compressed and converted to a data packet format (IP/UDP) that can be sent to the network. Latency is reduced by using hardware to encode the video, and by optimizing/minimizing the video processing required.
- Page 4 TECHNICAL NOTE 015 IP Ethernet latency measurement This is how the latency of the Harrier IP camera module was measured: • An application that shows the view of the camera on the PC monitor/display/screen is required e.g. ONVIF Device Manager (ODM), GStreamer. The camera was pointed at the PC screen.
- Page 5 TECHNICAL NOTE 015 Example System Setup: Harrier IP Camera: Profile: balanced_h264 (bitrate=0) • • Firmware version: v3.2 / v4.3 Connection: 1000BASE-T (wired) • Type: TCP / UDP • PC/software: • ThinkPad X1 carbon 6th Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz / 1.99 GHz •...
- Page 6 TECHNICAL NOTE 015 Latency measurements Camera Model Resolution & FPS Encoding Interval* Latency (ms) Cameras with Harrier IP Camera Interface Board technology 1080p60 ~140 Harrier 10x AF-Zoom IP Camera 1080p60 ~140 AS-CIB-IP-001-10LHD-A 1080p30 ~210 1080p60 LL ~140 Harrier 10x AF-Zoom IP/HDMI Camera 1080p60 ~175 (Tamron MP3010M-EV)
- Page 7 TECHNICAL NOTE 015 VideoEncoderConfiguration:: RateControl. ** Camera low latency mode Some AF-Zoom block cameras have low latency modes that can be turned on – however these reduce the amount of image processing and can affect the quality of the image (e.g. disabling lens/distortion correction functions) and restrict the ability of the camera to process the video data.
- Page 8 TECHNICAL NOTE 015 Summary Harrier IP cameras bring extremely low latency to the video system. While each element of a vision system will add to the overall latency, developers can address aspects of each component to reduce this as much as possible. In this note, we have made these recommendations to minimize latency: •...
- Page 9 Harrier 52x AF-Zoom IP Camera • Harrier 55x AF-Zoom IP Camera • Headquarters: North America: Active Silicon Ltd Active Silicon, Inc. 1 Waterside Court, Waterside Drive, 479 Jumpers Hole Road, Suite 301, Langley, Berks, SL3 6EZ, UK. Severna Park, MD 21146, USA.
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