![]() Often, the transition section allows background video and one or more keyers to be transitioned separately or in any combination with one push of the "auto" button.Ī Blackmagic Design ATEM 1 M/E broadcast switcher (fourth from top of rack), rack-mounted with other equipment in a typical live production environment. For this, the transition section can be switched from program mode to key mode. ![]() Usually, a key is turned on and off the same way a transition is. Note that instead of the key bus, other video sources can be selected for the fill signal, but the key bus is usually the most convenient method for selecting a key fill. chrominance, luminance, pattern (the internal pattern generator is used) or split (an additional video signal similar to an alpha channel is used) and can be selected in the keying section of the mixer. The digital on-screen graphic image that will be seen in the program is called the fill, while the mask used to cut the key's translucence is called the source. Here, one signal can be selected for keying over the program (or background) bus. A mixer can have more than one key bus, but often they share only one set of buttons. Common transitions include dissolves (similar to an audio cross fade) and pattern wipes.Ī third bus used for compositing is the key bus. The type of transition used can be selected in the transition section. Another button, usually labeled "cut" or "take", swaps the preview signal to the program signal instantaneously. Instead of moving the lever by hand, a button (commonly labeled "mix", "auto" or "auto trans") can be used, which performs the transition over a user-defined period of time. Note that in a flip-flop mixer, the position of the main transition lever does not indicate which bus is active, since the program bus is always the active or hot bus. ![]() This lever, similar to an audio fader, is used to transition between two buses. Both the preview and program bus usually have their own video monitors displaying the video selected in their respective buses.Īnother main feature of a vision mixer is the transition lever, also called a T-bar or Fader Bar. Some switchers allow the operator to switch between these two modes. These mixers are called flip-flop mixers, since the selected source of the preview and program buses can be exchanged. Most modern mixers, however, have one bus that is always the program bus, the second main bus being the preview (sometimes called preset) bus. Older video mixers had two equivalent buses (called the A and B bus such a mixer is known as an A/B mixer), and one of these buses could be selected as the main out (or program) bus. On the panel, a bus is represented by a row of buttons pressing one of those buttons selects the video signal in that bus. ![]() The most basic part of a vision mixer is a bus, which is a signal path consisting of multiple video inputs that feeds a single output. These are often used for VJing, presentations, and small multi-camera productions. There were a number of consumer video switchers with composite video or S-Video. Older professional mixers worked with composite video, analog signal inputs. They are used in live television, such as outside broadcasts, with video tape recording (VTR) and video servers for linear video editing, even though the use of vision mixers in video editing has been largely supplanted by computer based Non-linear editing systems (NLE). Most vision mixers are targeted at the professional market, with newer analog models having component video connections and digital ones using serial digital interface (SDI) or SMPTE 2110. Vision mixers may include Digital Video Effects (DVE) and still store functionality. Additionally, most vision mixers can perform keying operations (called mattes in this context) and generate color signals. Besides hard cuts ( switching directly between two input signals), mixers can also generate a variety of transitions, from simple dissolves to pattern wipes. ![]()
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