Over the last few decades, new technologies have emerged that have pushed the envelope for video and audio transmission. But there’s one technology that’s still in use today: SDI.
What is SDI technology? How does it work, and why is it useful? First, let’s explore SDI video technology and how it’s used with PTZ cameras.
What is SDI?
SDI video technology isn’t something new. SDI stands for serial digital interface, and it is the standard used for digital audio and video transmission over fiber-optic or coaxial cables. SDI can transfer data at speeds of 270 Mbps to 12 Gbps.
SDI was first developed by the Society of Motion Picture and Television Engineers. Since its emergence in 1989, multiple standards have been released:
- Standard definition
- High definition
- Enhanced definition
- Dual-link HD-SDI
- 3 Gbps SDI
- 6 Gbps SDI
- 12 Gbps SDI
- 24 Gbps SDI
SDI cables can transmit uncompressed video over a long distance, which is one of its great benefits. While new technology is available, SDI is still used to connect cameras, encoders, televisions, and more.
PTZ Camera Networking With SDI
Networking a single PTZ camera using an SDI is simple and straightforward. You’ll need to connect your camera to:
- A monitor
- The local network
Depending on your setup, you may also connect to an audio mixer and/or an SDI to NDI converter.
Cameras with a PoE (power over ethernet) feature make it easy to power the camera and stay connected to the network.
Many SDI cameras also have HDMI outputs, which allows you to connect to a monitor. However, you can also use the SDI output if you wish.
Once your camera is connected to the network, you’ll need to decide whether you will use a static or dynamic IP. Every camera that you connect to your network can have an IP address. For long-term use, a static IP is recommended. A dynamic IP will change periodically, which can make it challenging to manage your cameras and equipment.
This is the basic setup for an SDI PTZ camera.
A multi-camera setup is a bit more complicated but still relatively simple.
- The PTZ cameras are connected to each other using EVI DS cables.
- SDI cables connect the cameras to the video switcher
- An EVI control cable connects your cameras to the remote controller
- The switcher connects to a USB converter, which connects to a monitor
- The switcher also connects to the soundboard
The switcher plays a central role in the setup here. There are other ways to have a multi-camera setup, such as through PoE, which connects the cameras to the LAN and a livestreaming video controller.
There are multiple ways to connect a PTZ camera using SDI, but these are some simple and straightforward setups.
How Is It Useful?
The technology of SDI is still useful, even if newer technologies are available. An SDI cable:
- Can send uncompressed video signals over a long distance
- Can deliver broadcast-quality video
- It is compatible with most video equipment
- Allows for latency-free distribution of video signal
Despite being developed in 1989, SDI is still used today and, in fact, continues to evolve. The latest standard – 24 Gbps – was just released in 2020, so the technology continues to advance.
SDI Camera Pros and Cons
SDI cameras have both pros and cons, which you need to consider if you’re going to make a purchase. Let’s start with the pros first before seeing the few cons which may impact your decision to buy an SDI camera.
- Most video sources are compatible with SDI, so there’s less concern about users not being able to produce the content.
- Broadcast quality is clear and professional.
- Video can be sent, uncompressed over very long distances
However, some of these pros are also cons in some circumstances.
- Uncompressed video is much larger, which means the bandwidth demand of SDI is higher than competing technologies.
Bandwidth requirements are a concern for some professionals and not others. However, technology has rapidly advanced since SDI was introduced, and the concern of sending uncompressed video and images is slowly disappearing.
SDI technology has slowly started to be overtaken by NDI, but SDI tech is still widely used. The main reason that professionals stick with SDI is that it’s superb at sending videos over long distances without the need to compress them.