Methods, computer code products, devices, modules, systems, and encoders are disclosed which are configured to use an adaptive lag search window for determining a lag estimate for a current frame of information in an audio encoding system. The system can determine if the lag estimate is reliable and if not a new search window can be selected and a new lag estimate can be calculated based on the new search window. An adaptive threshold can be compared to the cross correlation for a lag estimate in order to determine whether the lag estimate is reliable. The system can also determine if an encoding gain is likely to be achieved using the prediction and if not, the computationally expensive time-to-frequency transformation can be avoided.