FIG. 6A is an illustration of the longest common subsequence identified within the pair of media signals of FIG. 4A. FIG. 6B is an illustration of the longest common subsequence identified within the pair of media signals of FIG. 4B. As shown in FIG. 6A, a diagonal of black squares indicates an unbroken longest common subsequence (because the reference and target signals are the same). However, in FIG. 6B, two frames have been removed from the target signal (what were originally the sixth and seventh frames), resulting in a discontinuity. The longest common subsequence is therefore frames 1-5 and 8-10 from the reference video signal. As described earlier, once the longest common subsequence is identified, contiguous subsequences may be tokenized and used to determine a set of edits describing the differences between the two signals. For example, the reference video signal in FIG. 6B could be represented by the string “ABC”, where the token “A” represents frames 1-5, the token “B” represents frames 6-7, and the token “C” represents frames 8-10. The target video signal could be represented, therefore, by the string “AC”, where the token “A” corresponds to frames 1-5 and the token “C” corresponds to frames 6-8. The edit distance between the strings “ABC” and “AC” is 1, the corresponding edit being the deletion of “B”. Thus, the set of edits is the deletion of “B”.