A system extracts, from uncoded video data, coding parameters that
correspond substantially to coding parameters used in a coding operation
that was previously performed on the video data. The system generates a
histogram for at least one AC frequency band in the uncoded video data and
calculates a correlation function for the histogram. A maximum value of
the correlation function is then identified, and a coding parameter for
the at least one AC frequency band is determined using the maximum value
of the correlation function.