A subjective video codec quality analyser (CQA) has been designed and implemented. It was specified to take two video streams as input: the original, uncompressed, stream and the compressed/decompressed stream. The CQA compared the subjective quality of the coded stream with respect to the uncoded one by computing the values of a number of factors designed to assess artefacts that were subjectively important. The values were then combined using a neural network to deliver, as output, a single quality measure that correlated with the subjective assessment of video data.