Audio synchronization Analog audio is difficult to handle. There
are frequency response problems, distortion problems (harmonic
and intermodulation), noise problems, and wow and flutter. Then
there is the signal level monitoring with two opposing concepts:
the VU meter and the PPM. Not surprisingly, analog video is also
difficult to handle. There are linear distortion problems (poor
frequency response, chrominance to luminance delay and gain
inequality to name a few), nonlinear distortion problems
(including luminance nonlinearity, differential gain and
differential phase) and noise problems. In the NTSC world,
picture information is transmitted in a synchronized manner.
Each picture requires precisely the same amount of time to be
transmitted. The analog audio accompanying the NTSC video signal
is continuous, and, like the analog video, is transmitted in
real time. Early television production had no lip-sync problems.
They started appearing with the use of video frame
synchronizers. These devices introduce a