1. Transmission interface: video based on SDI or IP (10G Ethernet)
For many years, broadcasters and other content providers have used SDI for uncompressed video transmission and have a complete infrastructure to support its operation. However, IP (Internet Protocol) transmission has become increasingly common. New IP solution reduces cost and provides flexibility in how infrastructure is implemented and increases scalability for higher data rates.
The Society of Motion Picture and Television Engineers (SMPTE) has defined interfaces based on SDI (ST-2082 for 12G-SDI) and 10G Ethernet (SMPTE-2022-5/6) for 4K video transmission. There are also a handful of studio-based video over IP proposals including Sony NMI, Evertz ASPEN and AIMS. Your system interface choice depends on the target infrastructure on the market. In most cases, you may need to support interfaces that maximize addressability, or meet your customers' requirements for heterogeneous video networks.So it is wise to design your hardware to support both SDI and IP solution
2. Transmission medium: coaxial cable or optical fiber?
Using 12G-SDI (or 10G Ethernet for SMPTE-2022-5/6) for higher speed data transmission increases losses in the transmission medium and reduces the total supportable cable length between the video source and sink. To deal with insertion loss and high frequency jitter at 12Gbps, signal conditioning components such as equalizers, reclockers, and cable drivers should be used to extend coaxial cable lengths up to 100 meters.
Optical fiber can be used as another transmission medium for applications that require longer transmission distances, but the system cost is higher. By using common form factors such as SFP+ (enhanced small form factor pluggable modules), you can use modules specifically designed to support out-of-order SDI video frames, including common extreme harsh environment data or modules that comply with SFF-8431 specification for 10G Ethernet video over IP based applications.
3. Transmission speed: 3G-SDI or 12G-SDI?
Currently, there are three ways to stream 4K content via the SDI interface. One method is to use 4 cable interfaces with each carrying 3G video data. The second method is to compress 12G data into a single 3G interface. The third method is to use single link uncompressed 12G-SDI.
The current market is choosing 4X3G-SDI or single linke 12G-SDI for 4K SDI transmission. But 4X3G-SDI solution may be totally replaced in the future, since it has two mode with 2SI or SQD format. This often causes trouble since not all equipments support both format. With the technology developing, single link 4K 12G-SDI solution will be supported by most equipments