AV-delay is a major issue in broadcast environment, AV-delays are the reason for Lip Sync errors. That is, movement of lips in the video and the corresponding audio do not match to each other, therefore too much lip-sync error can annoy the audience. AV-delay is measured in various ways e.g. the EBU has published a test pattern 3305 as can be seen in the illustration on the cover page of this application note. Unfortunately frame synchronizing leads coercively to AV-delays as described in this application note. AV-delay is inherent to the task of synchronizing. LYNX Technik AG resolved this issue by introducing a good compromise for compensating the perceptible AV-delay as described in the following chapters.
More on this topic in the Aplication Note.