Because of the limitations of the vinyl format, the ability to manipulate loudness was also limited. Attempts to achieve extreme loudness could render the medium unplayable. Digital media such as CDs remove these restrictions and as a result, increasing loudness levels have been a more severe issue in the CD era. Modern computer-based digital audio effects processing allows mastering engineers to have greater direct control over the loudness of a song: for example, a "brick wall" limiter can look ahead at an upcoming signal to limit its level.