 This widespread problem is another factor contributing to the demand for devices that defeat Macrovision.The signal has also been known to confuse home theater line doublers (devices for improving the quality of video for large projection TVs) and some high-end television comb filters.In addition, Macrovision confuses many upconverters (devices that convert a video signal to a higher resolution), causing them to shut down and refuse to play Macrovision content.