The bit rate required of a recorder mated to a video camera or functioning in the origination, post-production, or distribution is generally greater than the concurrent bit rate, real-time because of the error correction designed into the recording format. This “overhead” may increase the bit rate, sometimes by as much as one-third, and frequently sets a practical limit in systems design. Examples in the following table are intended only to clarify the definition. They indicate the range of some systems currently considered and a first estimate of their challenges.