Due to the high data rate of serial digital signals, they must be processed before being transmitted. Currently, the main connection between high-definition digital television production equipment is the serial digital component interface HD-SDI.
The code rate is Mbps. We know that analog signals also called continuous signals are sampled and quantized into signals that are not continuous in time and in amplitude also called discrete signals. Such signals are not yet digital signals and need to be converted into digital symbols Such as natural binary code , this code stream is not encoded by the baseband signal compression, larger code rate, take up a larger transmission bandwidth, this code stream transmission interface is SDI interface, also known as serial digital interface, It belongs to the channel code stream, so the SDI transmits a digital video signal that is not compressed after the sample is quantized you can also embed the audio.
SDI interface cannot transmit the compressed digital signal directly. After the compressed signal recorded by devices such as digital video recorder and the hard disk drive is played back, it must be decompressed and output through SDI interface to enter SDI system. Repeated decompression and compression, will inevitably lead to image quality degradation and delay increase, for which a variety of formats of digital video recorders and non-linear editing system, provides its own interface for direct transmission of compressed digital signals.
HDMI is the first digital interface that supports all digital high definition, multi-channel audio and smart format and control command data transmitted over a single cable without compression. HDCP technology by Hollywood and the giant semiconductor Intel co-launched, it can be actually used in video cards, DVD players and other transmission ends, as well as monitors, TV sets, between the receiving end of the projector.
Is an important anti-piracy technology for high-definition movies and television programs. The cable length of the DVI port can not exceed 8 meters. Some friends may think that HDMI is the latest digital interface, so the quality of the transmission than DVI is better, in fact, this view is wrong, in the effective transmission distance, HDMI and DVI are able to transmit digital video signals without loss, so There is no difference in terms of the quality of the transmitted digital video signal.
Therefore, when purchasing a monitor or a video card, it is not necessary to have an HDMI interface. It transports data, e.
Ok, that was the quick explanation. SDI is an umbrella term for a series of different standards for transferring video-related data. There are many different standards under the SDI-umbrella, e. Each of these is designed for a specific bit rate and video format. In other words, each can transfer an uncompressed video signal at a specific resolution. The higher the resolution and frame rate the camera can send to an external monitor, the more likely it will have a faster SDI-connection.
It backward compatible, so you can use it with slower standard monitors as well. That data then has to be interpreted in the recorder and encoded within the Atomos Recorder so that you can see an image on your screen. The reason is that SDI consists of a single strand of cable that works as a pipeline for serial digital data.
This makes it more stable over longer cable runs and less prone to interference. First of all, SDI is expensive. You pay a lot of money for the co-ax cable compared to other solutions such as Wi-Fi or fiber. But it will not be an easy transition between the two and people are still talking about SDI, despite the number of new studios and OB trucks that are now being built with IP foundations rather than its more venerable competitor.
Serial digital interface, to give SDI its full name, was developed to transmit uncompressed, unencrypted digital video signals around broadcast TV facilities. SDI was a major move on from analogue component video, which, with composite, had been one of the two main formats in broadcast video during the s. In those days TV centre installations demanded much more space, cabling and interfacing than they do now. This was largely due to the need for two routing systems; one for video, one for audio.
As part of this, each device had to be connected by three or four coaxial cables to carry the different video and audio elements. The beauty of SDI was the ability to carry digital component video and digital audio down a single coax cable.
Only one router was necessary because audio was embedded into the video signal. In that respect, SDI was a transformative technology but perhaps engineers and integrators working with it in the s did not imagine they would still be using it in Which isn't saying that SDI has not evolved over the last 31 years and adapted to changing needs.
New developments and standardisations were introduced to accommodate emerging formats and configurations as they arose. SDI is now classified by multiple standards for different technologies, resolutions and infrastructures. This specifies 3G-SDI, which signalled a key change in the way broadcast facilities were designed and installed. The bit-rate for SDI has continued to rise on a regular basis; from 3G it has gone to 6G and then 12G in rapid succession.
The question is whether users want to continue with what has become an increasingly constrained technology or move on to something that gives more capacity and flexibility.
Internet Protocol IP has been around in broadcasting since the s and is part of the general shift towards a more IT-oriented way of working.
It initially made inroads into broadcast as a replacement for ISDN Integrated Services Digital Network , which had become the standard for radio and other voice contribution connections.
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