Organisation of tests on component codecs for digital television transmission

Describes the way in which the tests were organised and discusses its relevance to the task in hand and indeed to other assessments in which equipment is developed and subjective tests held in widely separated laboratories. The candidate codecs were being developed in several laboratories around the world. Fortunately, however, 4:2:2 digital tape recorders (D1 format) had become available, fitted with the Rec. 656 parallel interfaces that were also required as inputs to and outputs from the candidate codecs. It was thus possible to test the codecs without moving them from the sites at which they had been developed by playing D1-recorded material into them and recording the output