1. What are some advantages of digital video
- Enhanced learning due to moving pictures are more effective than stills.
- The footage can be updated or changed easily.
- With network capablities, presentations can be distributed easily.
- Digital video adds a whole new dimension to presentations as it can be easily incorporated into computer presentations.
- Since digital videos are basically files, they can be integrated into many databases just like text or numeric fields for useful applications.
- What is meant by frame rate in video
Frame rate, or frame frequency, is the frequency (rate) at which an imaging device produces unique consecutive images called frames.
- Are all videos/movies the same frame rate, explain your answer
No this merely depends on what is being viewed. For example if a sports match were to be viewed it means that the frame rate would be higher because more movement would need to be conveyed through the camera. Whereas with something like an interview movement would not be as much therefore meaning that the frame rate would also be lower therefore not all movies/videos have a frame rate that is the same, they differ.
- What is meant by resolution, how is it measured.
Resolution is the result of the numbe rof pixels or dots used. The more pixel or dots used usually results in a higher resolution thus is higher clarity.
5. What is the colour system called RGB
This type of colour system is most commonly used for computers. The colours we see on the screen are created with light using the additive colour method, thus explaning why the RGB falls into the ADDITIVE COLOUR SYSTEM. Additive colour mixing begins with black and ends with white; as more colour is added, the result is lighter and tends to white.
Here is a spectrum of the RGB colours :
Here is a spectrum of the RGB colours :
The RGB colors are light primaries and colors are created with light. Percentages of red, green, & blue light are used to generate color on a computer screen.
- Explain the video standards PAL, NTSC, and SECAM, what are the main differences between them.
PAL
PAL this is short for Phase Alternating Line. This is the analogue video format most commonly used in television transmission. The name 'Phase Alternating Line' describes the way that part of the colour information on the video signal is reversed in phase with each line, which automatically corrects phase errors in the transmission of the signal. ( As opposed to NTSC recievers which have a tint or hue control to perform the correction manually).
The PAL colour system is usually used with a video format that has 625 lines per fram and a refresh rate of 25 frames per second, like NTSC this is also an interlaced format. Each fram consists of two fields (half-a-frame), each field has half o the lines of a frame. One generally has all the even lines whereas the other has all the odd lines). Fields are transmitted and dispalyed, there are generally 50 fields per seconds.
NTSC
'NTSC' stands for the National Television Standards Committee which sets the analog television standard for United States but has also been adopted by other countries such as Japan. The NTSC format consists of 29.97 interlaced frames of video a second, each consisting of 480 lines of vertical resolution out of a total of 525, the rest is used for other data. NTSC interlaces its scanlines, drawing odd numbered fields in odd numbered fields and even-numbered scalines in even numbered fields, which gives a nearly flicker- free image.
For colour NTSC includes a chrominance subcarrier,whose frequency is not a multiple of the horizontal scan frequency and therefore must be kept synchoronized by transmitting a colourburst signal. The colour burst consists of 8-10 cycles of the unmodulated subcarrier.
SECAM
SECAM stands for Sequential Couleur avec Memoire which is French for "sequential colour with memory". This is an analog television system which uses frequency modulation to encode chrominance information. It is named this because it uses memory to store lines of colour information, in order to eliminate the colour artifacts found on systems using the NTSC standard. This was developed for the same purpose as PAL but uses a different mechnaism to do so.This means that the vertical colour resolution is halved relative to PAL and NTSC.
- French SECAM is used in France and its former colonies
- MESECAM is used in the Middle East
- D-SECAM is used in the Commonwealth of Independent States and Eastern Europe.
- Which standard do we use in
Australia
Majority of the world uses PAL thus explaining why Australia uses the same.
- What is an IEEE 1394 port
IEEE 1394 ports are like USB ports, entry points for devices that you want to connect to your computer. This is done through an IEEE 1394 cable. This type of ports are most commonly used in Video Cameras.
9. Why do digital video cameras use video compression
We need to use compression in digital video because the high bit rates that result from the various types of digital video make their transmission through their intended channels very difficult. Even entertainment video with modest frame rates and dimensions would require bandwidth and storage space fair in excess of that available from CD-ROM. Thus deliering consumer quality video on compact disc would be impossible. Therefore compression is very essential in digital video.
- Describe what a codec is.
A codec is a device or computer program capable of encoding and/or decoding a digital data stream or signal.
11. What is meant by “generation loss”, where does it happen?
Generation loss refers to the loss of quality and potential increase of file size between subsequent copies of data. Anything that reduces the quality of the representation when copying, and would cause further reducation in quality on making a copy of the copy, can be considered a form of generation loss.
Thus, generation loss generally happens when copying a file or when transferring a file.
