HDMI Port vs. SDI Port? What is the difference?

HDMI Port vs. SDI Port

In our daily life, we often use SDI ports and HDMI ports. We are often familiar with the HDMI port, but not sufficiently familiar with the SDI port. To understand the difference between the two, you need to have a basic understanding of the SDI port and HDMI port.

SDI Port

The SDI port is a "digital component serial interface." SDI port is short for Digital Component Serial Interface (Serial Digital Interface).

The SDI interface is a "digital component serial interface", while the HD-SDI interface is a broadcast-level high-definition digital input and output port, where HD stands for high-definition signal. Since the SDI interface cannot directly transmit compressed digital signals, the compressed signals recorded by digital video recorders, hard disks and other equipment must be decompressed and output through the SDI port to enter the SDI system.

HD-SDI is widely used in non-linear editing post-production, broadcasting stations, etc. It is based on SMPTE292M, which is an interface specification for transmission at signal rates of 1.485 Gbit/s or 1.485/1.001 Gbit/s. The specification specifies the data format, channel encoding method, signal specifications for coaxial cable interfaces, connector and cable types, and optical fiber interfaces. The HD-SDI interface uses coaxial cable, while the BNC interface is used as the cable standard. The effective distance is 100m.

The SDI serial port is an interface that transmits each bit of the data word and its corresponding data sequentially through a single channel. Since the data rate of the serial digital signal is very high, it needs to be processed before transmission and belongs to the digital baseband signal. The SMPTE organization officially released 6G-SDI and 12G-SDI of the serial data interface in 2015. 6G-SDI is aimed at 2160p30 applications, which is 30 frames per second refresh. And 12G-SDI is aimed at 2160p60 applications (commonly known as true 4K), which is 60 frames per second refresh.

12G-SDI is for 2160p60 (commonly known as true 4K) applications, bai12G-SDI can integrate 4 lines for transmitting 3G-SDI signals into one, and directly transmit 4K audio and video. Corresponding to 60 frames per second refresh, with 12G-SDI, one cable can handle 4K transmission. In this way, fewer cables are needed, the system is simpler, and the image quality is more guaranteed. Moreover, 12G is backward compatible with 3G/HD/SD, so it is not a problem to access existing systems such as high-definition switchers.

HDMI Port

The full name of HDMI (High Definition Multimedia Interface) is a digital video/audio interface technology. It is a dedicated digital interface suitable for image transmission. It can transmit audio and video signals at the same time. The maximum data transmission speed is 48Gbps, and there is no need for digital/analog or analog/digital conversion before signal transmission.

Simply put, HDMI is a high-definition video interface, more common in mainstream laptops, LCD TVs, graphics cards, and motherboards. The HDMI interface supports 4K, 8K, and 10K full HD format video output. It is currently the most popular high-definition interface, which is unmatched by traditional VGA display interfaces. Just like phone broadband and optical fiber, the data transmission capability is very different.

Advantages of SDI Port over HDMI Port

SDI is more stable than HDMI transmission

Choose the standard transmission method (SDI signal) for the radio and television industry. The self-locking buckle design of the SDI interface is more stable and reliable, not easy to fall off, and will not cause signal interruption due to human factors, which is very important for live broadcast activities.

SDI has a longer transmission distance than HDMI

A serial interface refers to the sequential transmission of bitwise data. It is characterized by simple communication lines. As long as a pair of transmission lines can realize two-way communication, it is especially suitable for long-distance communication. Theoretically, the transmission distance of SDI can reach 100m, while the transmission distance of HDMI is usually within 30m.

SDI is cheaper than HDMI