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Tri-level sync is an analogue video synchronization pulse primarily used for the locking of high-definition video signals (genlock).
It is preferred in HD environments over black and burst, as timing jitter is reduced due to the nature of its higher frequency. It also benefits from having no DC content, as the pulses are in both polarities. [1]
Modern real-time multi-source HD facilities have many pieces of equipment that all output HD-SDI video. If this baseband video is to be mixed, switched or luma keyed with any other sources, then they will need to be synchronous, i.e. the first pixel of the first line must be transmitted at the same time (within a few microseconds). This then allows the switcher to cut, mix or key these sources together with a minimal amount of delay (~1 HD video line 1/(1125×25) seconds for 50i video). This synchronization is done by supplying each piece of equipment with either a tri-level sync, or black-and-burst input. There are video switchers that do not require synchronous sources, but these operate with a much bigger delay
The main pulse definition is as follows: a negative-going pulse of 300 mV lasting 40 sample clocks followed by a positive-going pulse of 300 mV lasting 40 sample clocks. The allowed rise/fall time for each of the transitions is 4 sample clocks. This is with a clock rate of 74.25 MHz. [2]
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
In electronics and telecommunications, jitter is the deviation from true periodicity of a presumably periodic signal, often in relation to a reference clock signal. In clock recovery applications it is called timing jitter. Jitter is a significant, and usually undesired, factor in the design of almost all communications links.
The NewTek Video Toaster is a combination of hardware and software for the editing and production of NTSC standard-definition video. The plug-in expansion card initially worked with the Amiga 2000 computer and provides a number of BNC connectors on the exposed rear edge that provide connectivity to common analog video sources like VHS VCRs. The related software tools support video switching, chroma keying, character generation, animation, and image manipulation.
Genlock is a common technique where the video output of one source is used to synchronize other picture sources together. The aim in video applications is to ensure the coincidence of signals in time at a combining or switching point. When video instruments are synchronized in this way, they are said to be generator-locked, or genlocked.
This is an index of articles relating to electronics and electricity or natural electricity and things that run on electricity and things that use or conduct electricity.
Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE in 1989. For example, ITU-R BT.656 and SMPTE 259M define digital video interfaces used for broadcast-grade video. A related standard, known as high-definition serial digital interface (HD-SDI), is standardized in SMPTE 292M; this provides a nominal data rate of 1.485 Gbit/s.
A pulse generator is either an electronic circuit or a piece of electronic test equipment used to generate rectangular pulses. Pulse generators are used primarily for working with digital circuits, related function generators are used primarily for analog circuits.
Professional video over IP systems use some existing standard video codec to reduce the program material to a bitstream, and then to use an Internet Protocol (IP) network to carry that bitstream encapsulated in a stream of IP packets. This is typically accomplished using some variant of the RTP protocol.
A vision mixer is a device used to select between several different live video sources and, in some cases, compositing live video sources together to create visual effects.
The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout a computer network. On a local area network, it achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems. PTP is currently employed to synchronize financial transactions, mobile phone tower transmissions, sub-sea acoustic arrays, and networks that require precise timing but lack access to satellite navigation signals.
Time base correction is a technique to reduce or eliminate errors caused by mechanical instability present in analog recordings on mechanical media. Without time base correction, a signal from a videotape recorder (VTR) or videocassette recorder (VCR) cannot be mixed with other, more time-stable devices found in television studios and post-production facilities. Most broadcast quality VCRs have simple time base correctors built in though external time base correctors (TBCs) are often used. Some high-end domestic analog video recorders and camcorders also include a TBC circuit, which typically can be switched off if required.
A video signal generator is a type of signal generator which outputs predetermined video and/or television oscillation waveforms, and other signals used in the synchronization of television devices and to stimulate faults in, or aid in parametric measurements of, television and video systems. There are several different types of video signal generators in widespread use. Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses or sync words. Generators of composite video signals will also include a colorburst signal as part of the output.
A digital delay generator is a piece of electronic test equipment that provides precise delays for triggering, syncing, delaying and gating events. These generators are used in many types of experiments, controls and processes where electronic timing of a single event or multiple events to a common timing reference is needed. The digital delay generator may initiate a sequence of events or be triggered by an event. What differentiates it from ordinary electronic timing is the synchronicity of its outputs to each other and to the initiating event.
In serial communication of digital data, clock recovery is the process of extracting timing information from a serial data stream itself, allowing the timing of the data in the stream to be accurately determined without separate clock information. It is widely used in data communications; the similar concept used in analog systems like color television is known as carrier recovery.
Audio-to-video synchronization refers to the relative timing of audio (sound) and video (image) parts during creation, post-production (mixing), transmission, reception and play-back processing. AV synchronization can be an issue in television, videoconferencing, or film.
Synchronous Ethernet, also referred as SyncE, is an ITU-T standard for computer networking that facilitates the transference of clock signals over the Ethernet physical layer. This signal can then be made traceable to an external clock.
White Rabbit is the name of a collaborative project including CERN, GSI Helmholtz Centre for Heavy Ion Research and other partners from universities and industry to develop a fully deterministic Ethernet-based network for general purpose data transfer and sub-nanosecond accuracy time transfer. Its initial use was as a timing distribution network for control and data acquisition timing of the accelerator sites at CERN as well as in GSI's Facility for Antiproton and Ion Research (FAIR) project. The hardware designs as well as the source code are publicly available. The name of the project is a reference to the White Rabbit appearing in Lewis Carroll's novel Alice's Adventures in Wonderland.
In video, frame synchronization is the process of synchronizing display pixel scanning to a synchronization source. When several systems are connected, a synchronization signal is fed from the synchronization source to the other systems in the network, and the video signals are synchronized with each other.
Black and burst, also known as bi-level sync and black burst, is an analogue signal used in broadcasting. It is a composite video signal with a black picture. It is a reference signal to synchronise video equipment, in order to have them output video signals with the same timing. This allows seamless switching between two video signals.
A pulse-cross is the representation of normally invisible portions of an analog video signal on a studio screen for error analysis.
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