Cutting Out the Noise - A Practical Guide to Video and Audio Compression - page 589

3. Live with it.
4. Re-record the program at a later date.
5. Re-orient your antenna to receive from a different transmitter.

36.4.8 Dropouts

A dropout occurs when there is a momentary loss of signal. How it appears on the screen
depends on whether it is an analog or digital effect. Blocks of randomly placed checker
patterns and lines indicate a digital dropout. Streaks or dots of white or black affecting
only one horizontal line at a time indicate an analog dropout (Figure 36-9).

Figure 36-9 Analog signal dropouts.

Solution?

1. Apply a dropout compensator.
2. Apply a median convolution filter.
3. Blur in the horizontal axis only.
4. Use a threshold filter to identify the white dots, select them, and reduce their
brightness.

36.4.9 Appliance Noise

This is caused by noise generated by home appliances breaking through via the mains cir-
cuits. If it is there in the recording, you can't do much about it. Filters that work with track-
ing and dropouts might help. For noise caused by washing machines, lawn mowers, and
hair dryers (Figure 36-10), the correct solution is the obvious one: Turn off the appliance
while ingesting video from your VCR.
If the problem is caused by your neighbor mowing the lawn, then either wait for the
mowing to stop or ask your neighbor (politely) to avoid doing this at critical times
when you want to record or ingest some footage. Moving to a remote location is another