ABSTRACT
The mix might not exist at all until its automation moves and effects have been rendered. Depending on the complexity of the track and the system being used, this rendering can take anywhere from a few minutes to a bit longer than real-time. The key to all modern psychoacoustic audio data compression is masking, the same phenomenon that powers high-powered noise reduction algorithms. A loud signal will hide a softer one at a similar frequency, even if they don't occur at precisely the same time. The amount of boost is noted so the frames can be restored to their original volume on playback. The algorithm measures how much energy the frame has at different frequencies. The number of frequencies is a trade-off: more bands allow tighter masking, but require sharper filters that respond more slowly. Adaptive Delta Modulation is an early encoding scheme that doesn't rely on masking. Instead, it makes a mathematical assumption.
