Common brands for commercial video mixers are Videonics. These pieces of hardware simply accept multiple video sources and combine them in various ways such as fades, wipes, and a number of other transitions. Another common piece of equipment in the DVJ arsenal is called a switcher. Most digital turntables, whether CD or DVD, have a fader-start capability, in which the cross-fader of the audio or video mixer can tell a player to pause or play. By using these types of switchers (the Pioneer A/V switcher is a very common example), scratching video effects can show the typical back-and-forth motion heard on audio. More-advanced video mixers also have a chroma-key capability, known by most as "green screen" compositing. Currently, Videonics makes a number of mixers that will allow for this effect. VJ artists may play DVD tracks with a certain color that is set as the chroma-key color on the mixer. The mixer will then locate this color on the track and replace it with whatever the VJ has chosen. Many times, he or she will use a camera and camera operator to take live video feeds of the dancing crowd and superimpose them on a video of something else to give a novel effect. A top end mixer option is the Pioneer SVM-1000, which has preview screens, switchers, video FX, and audio FX, all in a four-channel mixer. A standard setup can be the Pioneer DJM-800 with a VSW-1 Switch and a three-screen monitor. This kind of setup must have numerous media discs which must be transported to, or available at, the location. Swapping discs increases the changeover time for videos vs. a computer setup, and there's the possibility of skipping or stopping with scratched or damaged discs.