Cisco Explorer 8300 Guía de usuario descargar pdf (Pagina 46)

HDTV SECTION (CONTINUED)

The two HDTV formats :

720p 720 lines of horizontal resolution and progressive scan

1080i 1080 lines of horizontal resolution and interlaced scan

Q Which is better, 720p or 1080i? How do these compare with DVDs or the traditional digital terminal format?

A Progressive scan provides superior results compared to interlaced scan, the main difference being that interlaced scan’s

alternating lines are more readily visible to the naked eye.

While a 720p image contains fewer pixels than a 1080i image, it also can be refreshed more quickly, making it the better

choice for programs featuring a lot of movement, such as sports broadcasts.

To compare: both SDTV and DVD images use 480 horizontal lines with interlaced scan (480i). So-called progressive scan

DVD players provide images in 480p format, resulting in better picture quality.

What’s the resolution on Vidéotron’s HD channels? Can I choose the resolution of the signal I receive?

A Television stations decide which format a program will be broadcast in - although this doesn’t mean all of a station’s

programs will necessarily be broadcast in the same format.

It’s important to make the distinction between the image resolution you receive from a station, and the format your tele-

vision displays it in. For example: if a station broadcasts a program at 480i and you have a 1080i TV, it will convert the

image to a uniform 1080 onscreen lines by filling in the missing pixels. The program’s "real" resolution, however, stays

unchanged at 480i.

Q Can I record an HD program using my VCR?

A Some Vidéotron HD terminals let you record HD programs on your VCR. Of course, the VCR will have to decrease the

resolution in order to record it, so the recording will be in standard format. To preserve image resolution when recording

an HD program, it is suggested you use Vidéotron’s 8010 HD PVR.

Q I’ve noticed several captioning options in my HD terminal’s General Settings, such as font size and colour. Why are my

captions always in black and white?

A Make sure the Captioning Options in your General Settings are set to Personalized. Custom font size and colour are only

available for programs broadcast using the new digital captioning standard, EIA-708B. Programs broadcast using the old

captioning standard, 608, do support captions, but only in black and white. A program’s captioning standard is decided by

the television station.

Q What does an HDTV’s "native format" refer to?

A As you know, digital television programs can be broadcast in a variety of formats (480i, 480p, 720p, 1080i, etc.)—but TVs

are designed and built to display images in only one of these formats. This format is the TV’s native format. This is why

HDTVs must be equipped to convert the formats of the programs they receive.

HDTVs are often classified according to their native formats. Today’s models are designed to display images at either 720p

or 1080i. If an LCD TV with a native format of 720p receives a signal from a television station at 480i, it converts it to its

native format: 720p. To do this, it "fills in" the incoming image’s missing pixels, bringing it up to its display capacity. The

resulting image will always be in the same format: your TV’s native format.

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Cisco Explorer 8300 Guía de usuario Pagina 46