Sony DVP-NS999ES - Manual (Page 12)

ES Series DVD-Video/CD/SA-CD Players; Version 3.0 Page 12
MHz). This means that DVD samples the video luminance channel at
13,500,000 Hz (13.5 MHz), as part of the DVD-Video format specification.
Channel Bandwidth Sampling Frequency
CD Audio 20,000 Hz 44,100 Hz
DVD-Video 6,750,000 Hz 13,500,000 Hz
Digital recording systems sample the analog input signal at a specific
rate or frequency at least twice the highest frequency of the channel.
For DVD-Video, the sampling frequency is 13,500,000 times per second
(13.5 MHz).
Nyquist sampling only works properly if the analog output is carefully
filtered of the aliasing noise that the digital process incurs. Fortunately, the
aliasing noise is consistently higher in frequency than the highest video
frequencies we want to recover. The noise appears in clusters at each multiple
of the sampling frequency, plus and minus the video bandwidth. Unfortunately,
the noise is very close to the video frequencies. The player must use a very
steep analog filter, which must be carefully constructed to pass all the video
frequencies and block all the aliasing noise. Normally, even slight errors in the
analog filter could cut the highest video frequencies—degrading picture detail—
or allow some aliasing noise to pass through—degrading picture clarity.
While these requirements are difficult for interlace scanning, progressive
scanning sets even more stringent requirements. 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.
Luminance Channel (Y)
Bandwidth Luminance Channel (Y)
Sampling Frequency
DVD-Video Interlaced
Playback 6.75 MHz 13.5 MHz
DVD-Video Progressive
Playback 13.5 MHz, effective 27 MHz, effective
Progressive scanning effectively doubles both the video bandwidth and
the sampling frequency. While only the luminance (Y) channel is shown
here, this doubling also occurs for the two color difference channels (P
B
and P
R
).