Safety Track

Recorders and cameras offering dual-channel recording can capture one microphone twice, with the second channel set around ten or twelve decibels lower. The loud version is the one you use. If somebody shouts and the main channel distorts, you drop to the safety, lift it in the edit, and the moment survives with slightly more noise and no clipping. It costs nothing beyond a spare channel, which is why event coverage, interviews and any one-take situation lean on it heavily. Two limits are worth knowing. The safety only protects against level, so a badly placed microphone ruins both copies equally. And a recorder with a single input cannot produce one at all.