Understanding video technologies
- 3. PAL, SECAM, NTSC • Analogue television color encoding system used for broadcasting. • Varies in different countries: • These are NOT COMPATIBLE with each other. (This is why you need to choose your region before playing some DVDs)
- 4. Phase Alternating Line (PAL) • 625 lines • 25 frames per second(with the exception of Pal-M in Brazil. Pal-M is very similar to NTSC) • Parts of south America, Europe, Middle East, north and east Africa, most of Asia, Australia and New Zealand use PAL. • Has a frequency of 4.4 MHz.
- 5. National Television System Committee (NTSC) • 525 lines • 29.97 interlaced frames per second • Japan, south Korea, north America, and parts of south America use NTSC • Has a frequency of 3.5 MHz.
- 6. Sequential Colour with Memory (SECAM) • Also 625 lines • Russia, Mongolia, Madagascar, and west Africa use SECAM • Has frequencies of 4.4 and 4.2 MHz (alternating).
- 8. Standards conversion • Process of changing one analogue TV system to another (e.g. NTSC to PAL and vice versa) allowing content made from a different country to be viewed in different countries.
- 9. ASPECT RATIO
- 10. What is an aspect ratio? • The aspect ratio is a way to measure a size of a image, video or film. It can vary in length and width depending on what screen it is shown on / how far a projector is away from a screen however a ratio Is kept. • Five of the most common ratios are: - 4:3 - 3:2 - 16:9 - 1.85:1 - 2.39:1
- 11. Problems • Most film cameras will record in a wide screen aspect ratio (1.37:1) and old television aspect ratios were 4:3. This meant that the movie could not be viewed as it is filmed as to fit it on the screen would mean to cut off a significant amount of the movie off. • One solution to this was the ‘pan and scan’ where either the camera or the post production editing made the film move sideways for the audience watching on the television to see what was in the rest of the frame. • A more modern solution was letterboxing where instead of trying to fill the whole screen of the television with the film, they would place the film in the middle of the screen with blank space (black) showing on the top and bottom.
- 13. Composite video • Composite video cables are normally either just a single yellow cable (yellow is color code for ‘video’) or accompanied with red and white audio cables. • A composite video cable is made of all the components in a video signal (it’s limited to 480 lines which is standard definition).
- 14. Component video • A component cable separate the luminence and chroma parts of the analogue color signal which allows a better picture. Requires 3 cables color coded as red, blue and green. • A component cable is able to carry a high definition video unlike the composite video cable .
- 15. HDMI AND DVI
- 16. HDMI and DVI • HDMI (High definition multimedia interface) is a DIGITAL composite cable where both image and audio can be transferred. • DVI (Digital video interface) does not transfer audio. • The HDMI is a more preferred choice over DVI as it supports both audio and video, is high definition (1920*1200 max), and supports BluRay – another high quality piece of equipment. • DVI can be analogue or digital. It’s appearance is similar to that of a VGA cable (analogue only) however the prongs inside of the cable are different. The DVI cable also supports up to 1920*1200 but it doesn not support Blu Ray.