The development of the first SDI professional video standard can be dated back to 1989. This was done by the Society of Motion Picture and Television Engineers (SMPTE). After that, some updates have been made. Below are the SDI versions in the production order.
The most common types of SDI signals are 3G, 6G, 12G, and quad link SDI. The numbers in front of the Gs are the bitrates of the video. In a simpler form:
To stream 4K videos, the best SDI signals to use are 6G, 12G, and the quad link SDI.
HDMI is an acronym for High definition Multimedia Interface. It’s a video standard that’s used to transmit uncompressed video and embedded audio signals to any device that is capable of displaying or encoding videos. HDMIs are popularly used in consumer and prosumer environments. It is a highly favored connection cable because it is compatible with both consumer and professional devices. However, it is limited in length. It can only run up to 30 feet. For a longer range, you will need an amplifier.
Unlike SDI which was developed by a broadcasting industry to be the best method to transmit videos, HDMI was developed by a myriad of consumer electronics companies, cable providers, and movie producers.
Initially, the intention of these companies was not to develop a cable that can transmit both audio and video signals over a single connection. All they needed was a means to protect their content so that they won’t be plagiarized. In doing so, they standardized the use of HDCP (High-bandwidth Digital Content Protection) across all of their components. It’s a security standard that requires that the source device, such as a BlueRay player generates a security key so that the TV will be able to display your content. This is a tight protection that necessitates a handshake between the source device and the output device. This is the reason why most TVs won’t show an HDMI input on their source list if nothing is plugged in.
Here are the different types of HDMI signals:
The main factor to consider when choosing the best HDMI type for you is your need and available device. Are you using it for professional purposes, like home theater, or is it for personal use on a mobile phone? The answer to this will help you choose the right type of HDMI.
SDI cables are preferred because of their simple and reliable design. Also, they are very durable and easy to repair in the event of damage. However, the major advantage that makes SDIs stand out is the strong locking mechanism provided by the BNC cabling. This prevents the cable from disconnecting no matter how harsh it’s controlled. This is why it is used in broadcasts and outdoor environments where the subject and camera are moving frequently.
On the other hand, HDMI cables are preferred because of their popularity and simplicity. They are mostly used by consumers which makes them more familiar. Also, HDMI is usually used for different applications in homes.
While the SDI cable seems to be taking all the credit, there is a risk attached to its strong locking mechanism. When there is an accident, they will remain attached to the connected devices, which will cause mass damage. This can happen to even well-structured establishments like this.
The biggest drawback of the HDMI is the weakness of the locking mechanism. The connection is very fragile and any accidental bump can bring your live stream to a stop. This occurrence can make your audiences lose interest in your program and go for other alternatives. Also, the disconnection can cause great damage to your expensive equipment and this is not even to mention how difficult and expensive it is to repair HDMI cables.
SDI cables are mostly applied in situations where you cannot risk interruption or disconnection of your live stream like crowded events or outdoor venues with wildfire and harsh weather. The tight locking mechanism guarantees that the connection stays strong. In fact, some professionals don’t risk having HDMI cables in indoor venues, so they use an SDI cable. Also, they are applied in large spaces because of their long length.
On the other hand, HDMI cables are quite short in length, so they are commonly used in small rooms with clear pathways and controlled movement because of the flimsiness of their locking mechanism.
SDI was developed by a broadcasting company with the main aim of providing the best video quality, which they achieved. SDI is a one-way, multiplexed standard developed to transmit the highest quality of video over a coaxial cable. The video quality produced by SDI is flawless.
HDMI, on the other hand, was primarily developed by movie producers, electronics companies, and cable providers to safeguard their content. Their intention was not to produce high-quality videos, hence HDMI cables fall short of transmitting ultra high-resolution videos like 4K videos.
SDI cables can be as long as 300 feet, while the maximum length that an HDMI cable can be is 30 feet. This makes SDI more applicable in digital video broadcasting and familiar applications where connected devices will be separated more than 30 feet away. However, HDMI length can be increased by using amplifiers or repeaters.
The bandwidth varies according to the type of SDI and the type of HDMI. However, generally speaking, the SDI comes at the top for this section. You can have an SDI cable that supports as much as 12Gbps, but HDMI only supports as much as 5Gbps.
As earlier stated, SDI cables have BNC connectors that ensure that the connection is not pulled out. In fact, it is very strong that it has to be rotated to uncouple the connector from the port. This definitely cannot be done by accident; it must be deliberate. But HDMI doesn’t have this. At the sight of any turbulence or wind, they can be disconnected.
SDI cables are made up of standard coax cable (RG-6), which is readily available and relatively cheaper than the proprietary cable used for HDMI. SDI allows you to reduce costs and save more.
The security system of the HDCP protocol used in developing HDMI mandates that when an HDMI device is connected and powered to the camera, the two devices must communicate with each other. This is called a “handshake.” This is compulsory as it is part of the protection standards of the HDCP protocol. The two devices report to each other to check if they are compatible or not.
Well, this is a problem because if the signal going from the camera to the device drops below the expected level, the two devices will need to start another connection establishment. And this delay cannot be tolerated in a live event as it will stop the broadcast.
Luckily, SDI is not developed with HDCP, hence it doesn’t need to go through all these steps to secure a strong connection. This is why it is preferred for live stream events.
This is similar to the point above. HDMI only responds after it has complied with the standards of the HDCP. The several HDCP protocols slow down the connection speed of the HDMI. But SDI responds quicker and smoother while it is even switching videos.
Another thing SDI boasts of is its backward compatibility. HDMI, on the other hand, does not have backward compatibility. For the HDMI to be compatible backward, you need a VGA or HDMI converter to get the security key. With this, you can establish a connection from the source to the receiving device. This is another effect of the HDCP.
HDMI does not support time code, while SDI transmits video signal and time in one single cable.
HDMI connectors are similar to a USB that can be easily unplugged intentionally or not. They don’t have a tight lock which makes them very easy to remove. SDI, on the other hand, has strong connectors that are held in place by BNC cabling. HDMI cannot be used in places where there are a lot of connected wires. This is because while trying to remove another wire, the HDMI connector can be affected.
HDMI, even though it was not created with the intention of transmitting data, one of its salient benefits is that it helps to secure personal content. Due to the protection provided by the HDCP, there is a hard wall separating your content from plagiarizers.
HD-SDI was created with the intention of providing the best way of transmitting high-quality data quickly from the camera to the receiving device. The cable was designed with all preciseness to carry out its function perfectly, and it works in situations where HDMI will falter.
HDMI’s primary disadvantage is that it can be easily disconnected due to some unintentional touches, thereby causing a stop in the live stream. Another disadvantage is that it’s limited by length. You can use it for a large room unless you add amplifiers or repeaters to it. One other drawback is that it cannot really be trusted with very high-quality data as it is very slow in transmission and won’t produce the desired quality.
The major drawback of the HD-SDI is that if it’s going to get damaged, it takes other connected devices with itself.
HDMI has a different mechanical design. The connectors used for HDMI cables are less-reliable to SDI. HDMI connections can be likened to USBs; they are flimsy and can’t be locked in place. They will definitely get disconnected due to a little pressure.
SDI, on the other hand, is made with a stronger and more reliable cable. It is locked by BNC connectors that guarantee continual connection no matter the pressure it’s faced with.
A major reason why HDMI is used by consumers and not professionals is that it cannot produce the desired quality. HDMI produces a lesser video quality when compared to SDI. It cannot be trusted with high-resolution videos.
Once again, SDI comes top. The bandwidth used by HDMI is lower than SDI’s. This means that SDI transmits more data rate per second when compared to HDMI. SDI can transmit as much as 12G per second, but HDMI can only handle 5G per second.
SDI is ideal for a venue that’s filled with people like concerts and sporting events. Also, it is suitable for outdoor venues with wildlife and strong wind as you wouldn’t want your broadcast to be interrupted by the disconnection of your connection cable. This is also why they are used for important broadcasts like emergency declarations.
HDMI should be used only for indoor events where you know that you can control the crowd and restrict people from interfering with your connections. If they are used in other applications, there is a high risk that your connection will be mistakenly interrupted, which will upset your audience.
Neither SDI or HDMI are better than each other. In this context, the definition of better will be determined by your streaming application. If you need a connection cable for outdoor venues streaming, then SDI is better. But if all you need is a connection cable for a small indoor event, you can go with HDMI.
To have the best SDI and HDMI productions, you need to partner with one of the best PTZ camera manufacturers that know the in-and-out of video outputs, connection interfaces, and live streaming. Telycam does not just provide PTZ cameras, but also offers high-quality wholesale webcams that are compatible with different types of connection cables, including SDI and HDMI. If you are in need of the best SDI and HDMI cables for your production, reach out to them.
SDI (Serial Digital Interface) and DVI (Digital Video Interface) are both related, however, the difference that exists between them is that DVI can only transmit videos, while SDI can transmit videos and audios. Another difference is that DVI supports the use of HDCP (High Definition Content Protection). Movie producers who want to protect their content usually use this against unauthorized copying.
ASI (Asynchronous Serial Interface) is a cable that is capable of transmitting COMPRESSED data that include multiple programs. SDI, on the other hand, is capable of carrying UNCOMPRESSED data that consist of a single program.
Both of them are compatible with BNC connectors, but they cannot be used interchangeably.
DVI and HDMI are very similar in the sense that they both support the use of HDCP for protecting people’s content from plagiarism. However, despite DVI backward compatibility with HDMI, it cannot transmit audio data. DVI is primarily designed for video data.
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