BASIC TECHNICS OF THE IMAGE

“BROADCASTING SYSTEMS”

WHAT IS BROADCASTING?

Broadcast television systems are encoding or formatting standards for the transmission and reception of terrestrial television* signals. There are three main analog television systems in current use around the world:  NTSC, PAL, and SECAM. 

* Terrestrial television is a mode of television broadcasting which does not involve satellite transmission or cables typically using radio waves through transmitting and receiving antennas or television antenna aerials.

PAL SYSTEM

PAL, short for Phase Alternating Line, is an analogue television color encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM.

PAL was developed by Walter Bruch at Telefunken in Germany. The format was unveiled in 1963, with the first broadcasts beginning in the United Kingdom and West Germany in 1967 the one BBC channel which had been the first UK TV service to introduce "625-lines" in 1964.

SD ( Standart Resolution ) PAL’s ratio by pixel is 720(w) 576(h). 720

576

PAL Broadcasting System uses 25 frame per second. It is very near to cinematographic recording system. The aspect ratio of the PAL System is 4:3. But only for SD, the ratio can be changable to 16:9 with the aid of cache.

4:3 16:9

CACHE

CACHE

“576i” is a standard-definition video mode used informer PAL and SECAM countries. In digital applications it is usually referred to as "576i"; in analogue contexts it is often called "625 lines"

NTSC System

NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, parts of South America (except Brazil, Argentina, Uruguay, and French Guiana), Myanmar, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories.

There is a large difference in frame rate between film, which runs at approximately 24.0 frames per second, and the NTSC standard, which runs at approximately 30 (29.97) frames per second.

Unlike the 576i video formats, this difference cannot be overcome by a simple speed-up.

SD ( Standart Resolution ) NTSC’s ratio by pixel is 720(w) 480(h).

720

480

In digital applications it is usually referred to as “480i"; in analogue contexts it is often called “525 lines"

What Does “i” Mean? The “i” is a short of the word “interlace” Since the interlaced signal contains the two fields of a

video frame captured at two different times, it enhances motion perception to the viewer.

Interlaced scan refers to one of two common methods for "painting" a video image on an electronic display screen (the other being progressive scan) by scanning or displaying each line or row of pixels. This technique uses two fields to create a frame. One field contains all the odd lines in the image, the other contains all the even lines of the image. A PAL-based television set display, for example, scans 50 fields every second (25 odd and 25 even). The two sets of 25 fields work together to create a full frame every 1/25 of a second (or 25 frames per second), but with interlacing create a new half frame every 1/50 of a second (or 50 frames per second).

VTR head

PAL uses 625 Tvline for making one picture. When the VCR Head turns, first head write 312 TVline then, other head which is situated 180 degree, write last 313 Tvline. At the end, 625 makes a interlaced picture. So in one field there are 2 4 6 8 10 …. 312 Tvlines, in other field there are 1 3 5 7 9…313 Tvlines.

HD (High Definition) HD video can be thought of as the third

generation of video technology. Analog video was the first, offering instantaneous playback of recorded images. Next came digital video, which emulated the analog video process in the form of digital data, opening up the possibilities of non-linear editing. HD video represents another paradigm shift. Not only is HD "larger" than older forms of video (in resolution, screen size, digital and file size), but as we will see, it is uniquely "flexible," with more technical variables.

So what is HD?

Hi-definition video is more than just a name to indicate an image has higher resolution than previous video forms, rather HD is a specific technical specification that all major hardware manufacturers and software developers have agreed upon for the future of film, TV, video and broadcasting.

The HD specification dictates a number of areas of the HD format but most particularly and importantly it specifies the frame size and dimensions of the image. Existing Standard Definition (SD) has fixed dimensions of 720 pixels wide x 576 pixels high for PAL and 720x480 for NTSC. The HD spec allows for two different HD frame sizes; a smaller 1280x720 and a larger 1920x1080. The larger of these being nearly three times the size of SD.

There is 3 leading HD subformats:Full HD 1920 X 1080HDV 1440 X 1080

1280 X 720These pixel aspects is constant for PAL and NTSC. The nature aspect ratio for HD Systems is 16:9.Most common indication of Full HD is “1080i/p” or HDV is “720p”.

A Full HD frame is bigger and more qualified 5 times than a SD frame.

1920 X 1080 =  2,073,600 pixel

720 X 576 = 414,720 pixel

2.073.600 / 414.720 = 5

Cinematic System A normal speed of cinematic system

is 24 frame/second. There is no other system as PAL SECAM or NTSC.

You can change the frame rate speed. There is 4 types of film stocks.

8mm Amateur16mm Semi Professional35mm Professional70 mm IMax

How a cinematic camera works?

Basic operation: When the shutter inside the camera is open, the film is illuminated. When the shutter is completely covering the film gate, the film strip is being moved one frame further by one or two claws which advance the film by engaging and pulling it through the perforations.

How We Convert Film Systems to Eachothers Telecine is a word combined by Television and Cinema Telecine is the process of transferring motion

picture film into video and is performed in a color suite.

Telecine enables a motion picture, captured originally on film stock, to be viewed with standard video equipment, such as television sets, video cassette recorders (VCR) or computers. This allows film producers, television producers and film distributors working in the film industry to release their products on video and allows producers to use video production equipment to complete their filmmaking projects.

However, the difference in frame rates between film (generally 24 frames/s) and television (30 or 25 frames/s) meant that simply playing a film into a television camera would result in flickering when the film frame was changed in mid-field of the TV frame.

NTSC: pulldown 3:2 PAL: pulldown 2:2

ANY QUESTION?