SDI Cable: All You Need to Know How to Choose the Cable You Need

What is it that you need to look for in an SDI cable? Should you go for an HDMI connector or an SDI one?

We take a look at the SDI interface, the different types of SDI cables, and how these can be a better choice in many instances.

Do cables such as SDI or HDMI confuse you? Don’t worry. This article will help you pass through the turbulent waters of cable.

Video SDI cables

Chapter 1: What is SDI Cable?

Now, what is SDI? SDI stands for serial digital interface or SDI cable in short. It is a standard used for transmitting digital video over long distances. It is the most common cable found, all the broadcasters prefer SDI and use it.

The cable that connects your TV set-top boxes or your TVs is probably SDI cables. SDI cable belongs to the family of digital video interfaces. The Society of Motion Picture and Television Engineers [SMPTE] gave its name in 1989. It is pretty old compared to HDMI, display port, DVI, or VGA connector. You can think of SDI cable as a grandfather, while the others as grandchildren.

SDI cable was first standardized in 1989, but it’s 2019 now. SDI cable has gone through many upgrades over the decades. The enhancements were mostly done to increase signal quality and transmit more data.

About SDI Cable

Whether you are watching a live show or just regular television, SDI cable is what that is bringing you that feed. The reason for the SDI cables preference over other cables is:

  • Transmission of audio and video over the long-range [300ft]. Amplifiers and repeaters increase this range even further.
  • Has a BNC connector which has a lock-in mechanism.
  • Cheaper compared to other cables as it is mass-produced.
  • It’s reliable, robust, and sturdy.
  • Works wonders while sending uncompressed audio and video signals.

SDI Cable Macro slot

Types of SDI Standar

Now, there are various standards of SDI cable. Here is a look.

  • SD-SDI with a bit rate of 270Mbit/s introduced in 1989. It can transmit a video format of 480i, 576i.
  • HD-SDI with a bit rate of 1.485Gbit/s introduced in 1998. It can transmit a video format of 720P/1080i.
  • 3G-SDI with a bit rate of 2.970Gbit/s introduced in 2006. It can transfer a video format of 1080P 60F/s.
  • 6G-SDI with a bit rate of 6Gbit/s introduced in 2015. It can transmit a video format of 4K 30F/s.
  • 12G-SDI with a bit rate of 12Gbit/s introduced in 2015. It can transfer a video format of 4K 60F/s.
  • 24G-SDI is already in development, which will have a bit rate of 24Gbit/s.

Video Payload and Blanking

Now time for some technical stuff. Do you know how data goes through? Here is a simple rundown. The data go in packets, called payloads. Whereas, the information about the destination is in the header. Video payloads in the earlier versions of SDI were a far cry compared to the new ones. The higher the video payload, the higher will be the video definition. Have you ever wondered how the secondary data such as subtitles, stock files, etc. come in your live feed? This answer is blanking. Blanking is the interval between the end of the last line of the frame to the first line of the next frame. 

There are three types of blanking – Horizontal, Vertical, and Fields. Blanking was earlier used for better video quality during the period of CRT TVs. Nowadays, it’s more to carry secondary data and audio-video synchronization. SDI cable uses a real-time transport protocol [RTP]. It helps in the real-time transmission of data on multiple channels. This also helps in better payload and hence, better video quality.  

 

Chapter 2: SDI Check and SDI Status Display

 SDI checking is important. Some tests are a must for ensuring that SDI is performing satisfactorily. Some of those checks are:

  • SDI check field
  • In-service testing
  • Eye pattern testing
  • Jitter testing

SDI cables go through these checks. It results in the brilliant transmission of audio and video. SDI status display also gives a summary of several physical layer measurements. For one, this helps in the better configuration. There is an automatic change of the filter settings according to the signal. During configuring the settings for the transmission, these work wonders.  

 

Chapter 3: Do You Need SDI Interface – moving from Analog to Digital?

What many people worry about is signal integrity. That is whether or not your signal will reach its destination without alteration. I’ll be honest here. No matter what cable you are using, there will be some loss during transmission.

The only thing you need to worry about is whether that loss will have a significant effect or not? If you couldn’t understand, then let me make it simple.

Let’s start with the basics. All of you know signal in the form of analog or digital carries data. Analog transmission used to be the standard in the early 60s, 70s, and before. Now the digital signal is the undisputed king [no kidding].

The earlier coaxial cable uses analog cables. However, the transmission loss was pretty high. Analog signals transmit data in a waveform. And when alteration happens, it is progressive and continuous. In simple words, the more noise, the more the degradation in signal.

Digital signal stores and transmit data in the numeric value of 1& 0. This is not just easy for transmission but allows less alteration as well. Due to this, most cable nowadays uses digital signal, and SDI is no exception.

So, if you want to transmit data, the digital signal is the best. If you still use analog signals, you should consider moving to digital.

Custom SDI Cables

 

Chapter 4: Selecting the Proper Manufacturer for SDI Cable Assembly

Looking for the best SDI Cable assembly services?

You can find the SDI port in every major camera. If you’ve ever been to a stadium during a live event, you can see many camerapersons holding cameras. If you look closely, you can see a lot of black wires. Those are none other than SDI cables. It may seem a bit crazy. However, here is the thing. The total length that you see while live streaming is several Kilometers. If you use HDMI or any other cable, it’ll probably burn your pockets – and I am not kidding.

It would help if you had a custom SDI Cable manufacturer you can trust. At CLOOM Tech, you’ve got the right experts to help you.

Have high-bandwidth applications that need a 125 meters transmission distance? We can help you get the SC-DZ type RG7 cable to help you out. Want to go the economical way? Try out our choices of RG6 cable.

We can help you design SDI repeaters that can accept two signals together. Or even convert copper SDI signals into optical SDI format. This will help for extra long cable runs of over 300 meters. 

Our cable rating is according to the frequency [Giga Hz]. The higher the Giga Hz, the higher will be the bandwidth. Higher bandwidth equals better video and audio quality.

Many manufacturers make SDI cables, but you need professionals you can trust. We can custom-assemble SDI cables according to your needs. Choose from Triax, coax, fiber, or audio cables.

Each comes with their cable and connectors. Talk to us to know more about how we can help.

 

Chapter 5: HDMI vs. SDI: What’s the Difference?

Now the million-dollar question, which I am sure a lot of you want to know. What is the difference between HDMI and SDI?

HDMI stands for high definition multimedia interface. SDI stands for serial digital interface. Both are for the transmission of audio and video signals. There are few differences between them such as

  • SDI cable uses BNC [British naval connector] connector, whereas HDMI uses the HDMI connector.
  • HDMI uses high bandwidth digital content protection [HDCP] for protection, whereas there is no such protection in SDI.
  • Speed in HDMI cable is a bit slower due to HDCP than SDI.
  • HDMI cable has 19 pins, whereas SDI cable has only one pin.
  • HDMI cables are more expansive than SDI cables.
  • SDI cables are reliable, and their connectors don’t break easily compared to HDMI cables.
  • HDMI cable is more oriented towards consumers. SDI cable orient towards professionals.

HDMI Cable

 

Chapter 6: SDI Cable vs. Coax

Coaxial cable is the simplest type of cable found. Coaxial cable has a central core, and it is either of aluminum and copper, clad in a dielectric constant. A braided copper mesh surrounds it for shielding, and finally, the insulator over it. 

  • Coaxial cables have a male connector at the ends which connect to the female connectors. They are most commonly used in cable television.
  • SDI is a transmission format. It uses coaxial cables along with BNC [Bayonet Neil Concelman] connector.

The reason for the use of coaxial cable is that it is very cheap compared to other cables. All the major institutions, whether be it the military, bank, telecom, uses SDI.

So, you can think of coaxial cable as a part of SDI transmission.

 

Chapter 7: SDI Cable vs. BNC

As you already know about SDI, I will talk about the BNC connector. BNC connector has a male mounted connector with the pin connected to the central core. A ring is there with the male member to fasten it to the female member. This lock-in function is one of the best reasons why BNC connectors are sturdier than their peers.

  • You don’t want HDI Connectors Always

I am sure you wouldn’t want your wires pulled from the ports every time someone trips over it. SDI cable uses a BNC connector, which is very reliable and does not break easily. HDMI connectors are a pain in the neck precisely because of their fragile nature.

  • It’s Inexpensive

SDI cable is one of the most versatile and useful cables. Professionals all over the world love it. It’s ease in handling, reliability, inexpensive nature all add to the charm. But no one is perfect, and SDI cable is no exception either. Though it can transmit a signal over long distances, it can’t compare to the Fibre.

  • You save on costs

To compete with Fibre, you need repeaters and amplifiers. It will significantly increase the cost. It has a lower bandwidth compared to HDMI. And as of now, it can’t send a signal with a bit rate above 12Gbit/s. However, the best selling point of SDI cables? It can alter video characteristics. You can change the ISO or white balance in real-time.

BNC Connector with Coaxial cable

 

Conclusion

I am sure you wouldn’t want your live baseball game to stream late due to video editing, right. The broadcasting and TV industry use SDI cables on a large scale. They got popular during the 1980s and since then have become the go-to cables.

A new transmission medium, that is, Fibre, is gaining ground more in recent times. But it has a long way to go before it can disrupt the SDI foundation. If you want a signal over the long-range at a friendly cost and good quality, SDI cables are the way to go.

With CLOOM Tech, your search for a good SDI cable manufacturer ends too. Talk to us about how we can help you do more for less.

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