Types and differences of SDI cables
SDI cable is a kind of cable commonly used in high-definition video signal transmission. Its full name is Serial Digital Interface, that is, digital component serial interface. SDI cable can transmit uncompressed digital video signal through ordinary 75 ohm coaxial cable, which has the advantages of long transmission distance, stable signal and strong anti-interference. SDI cables are widely used in radio and television, monitoring, live broadcast and other fields, and are an important interface type for professional video equipment connection.
Main Types of SDI Cables
According to the transmission rate and resolution, SDI cables can be divided into the following main types:
SD-SDI：Standard-definition digital component serial interface with a transfer rate of 270Mbps and supports standard-definition video formats such as 480i and 576i.
HD-SDI：High-definition digital component serial interface with a transmission rate of 1.485Gbps, supporting high-definition video formats such as 720p and 1080i.
3G-SDI：Three-generation digital component serial interface with a transmission rate of 2.97Gbps and supports full HD video formats such as 1080p 60Hz.
6G-SDI：The six-generation digital component serial interface has a transmission rate of 6Gbps and supports 4K ultra-high-definition video formats such as 2160p 30Hz.
12G-SDI：The 12th generation digital component serial interface has a transmission rate of 12Gbps and supports true 4K ultra-high-definition video formats such as 2160p 60Hz.
The following table lists the main parameters of various SDI cables and the corresponding SMPTE (Society of Motion Picture and Television Engineers) standards:
| Standard | Name | Release time | Working rate | Digital video format |
| SMPTE 259M | SD-SDI | 1997 | 270Mbps | 480i,576i |
| SMPTE 292M | HD-SDI | 1998 | 1.485Gbps | 720p,1080i |
| SMPTE 424M | 3G-SDI | 2006 | 2.97Gbps | 1080p 60Hz |
| SMPTE ST-2081 | 6G-SDI | 2015 | 6Gbps | 2160p 30Hz |
| SMPTE ST-2082 | 12G-SDI | 2015 | 12Gbps | 2160p 60Hz |
The difference between SDI cable and HDMI cable
HDMI cable is another cable commonly used for high-definition video signal transmission. Its full name is High Definition Multimedia Interface, which is high-definition multimedia interface. The HDMI cable can transmit parallel signals through a 19-pin line, supports simultaneous transmission of audio and video, and has the advantages of high image quality, good compatibility, and simple operation. HDMI cables are widely used in home theaters, game consoles, computer monitors and other fields, and are an important interface type for consumer video equipment connections.
SDI cable and HDMI cable have the following differences in structure, function and application:
Structurally, SDI cables use a single coaxial cable to transmit digital serial baseband signals, while HDMI cables use multi-core balanced cables to transmit digital parallel signals. Therefore, SDI cables are simpler, more durable and cheaper than HDMI cables.
Functionally, the SDI cable can only transmit video signals, while the HDMI cable can transmit audio and video signals at the same time. Therefore, HDMI cables are more comprehensive, convenient and intelligent than SDI cables.
In terms of application, SDI cables are mainly used in professional fields, such as broadcast TV, monitoring, live broadcast, etc., while HDMI cables are mainly used in consumer fields, such as home theaters, game consoles, computer monitors, etc. Therefore, SDI cables are more stable, long-distance and high-definition than HDMI cables.
Precautions for SDI cables
When using SDI cables, you need to pay attention to the following points:
When purchasing an SDI cable, pay attention to the label of the cable, and do not confuse the SDI cable with the SYV75 cable. SYV75 cable is a coaxial cable for analog video signal transmission, it cannot be used for SDI signal transmission, otherwise it will cause problems such as unstable transmission and short distance. The label of the SDI cable is usually coded on the surface of the cable, such as RG6, RG59, etc.
When connecting the SDI cable, pay attention to the type of the interface, and don't confuse the SDI interface with the Q9 connector. The Q9 connector is a universal coaxial cable connector that can transmit both analog and SDI signals. But not all Q9 connectors can output SDI signal, you need to refer to the specifications of the equipment. Generally speaking, the Q9 connector of the SDI interface will have a small dot mark, but the Q9 connector of the analog interface will not.
When using SDI cables, pay attention to the matching of signals, and do not confuse different types of SDI signals. Different types of SDI signals have different transmission rates and resolutions, which need to match the equipment and monitors to work properly. Generally speaking, high-rate SDI signals can be backward compatible with low-rate SDI signals, but not vice versa.