Sony NS3100, DVP-NS9100ES manual MH ｚ-Sampling Analog-Filter

samples. 8X oversampling inserts seven additional samples. And 16X oversampling inserts fifteen additional samples.

The benefit is this: in the process of generating additional samples, oversampling shifts the aliasing noise up in frequency, opening up substantial room between the video signal and the noise. With more room, we can relax the design of the analog filter, which can be far milder in slope, and far more effective at optimizing both the picture detail and the picture clarity.

27 MHｚ-Sampling
	Analog-Filter
Video	Noise	Noise	Noise	Noise	Noise	Noise	Noise	Noise
Signal
	27	54		108				216
54 MHｚ-Sampling

Video	Noise	Noise	Noise	Noise
Signal
27	54	108		216
108 MHｚ-Sampling
Video		Noise		Noise
Signal
27	54	108		216
216 MHｚ-Sampling
Video				Noise
Signal
27	54	108		216

These diagrams show interlaced video and the need for oversampling. At 27 MHz sampling (top), the design of the filter (red curve) must be extremely steep to avoid cutting into the video detail (blue) or passing some of the noise (pink). At 54 MHz (second from top), the filter is somewhat better. And at 108 MHz (third from top), the filter becomes better still. Oversampling at 216 MHz (bottom) leads to a far more effective analog low-pass filter. This enables the Sony® ES Series DVD players to deliver all the picture detail, without degrading the clarity of the image with noise.

Oversampling, which is useful for interlaced video, becomes indispensable for progressive scanning video. Because progressive scanning outputs twice as many horizontal lines per second, progressive playback effectively doubles channel bandwidth to 13.5 MHz and doubles sampling frequency to 27 MHz. Players need a minimum of 27 MHz sampling in order to output a progressive signal.

ES DVD Players 2005, Version 4.0 Page 20