 A MIDI mockup allows the director, or executive producer, to hear the compositions in a setting that approximates their final version, and thus to approve or alter the project before the budget has been committed to record the actual instruments.MIDI mockups first came into wide use in the 1980s, when synthesizer and sampler technology developed to the point where it could create approximate replicas of acoustic instruments.Large film-scoring studios would build systems with dozens of sound modules, all linked to a single sequencer that would play back the MIDI version of the score.