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In this article:
- What is Digital Video
- Image capture formats
- Advantages of Digital Video
- Digital Video Storage Formats
What is Digital Video
A video recording system that makes use of a digital representation of a video signal instead of an analog representation is called digital video. It is typical of digital video recordings to be stored on commonly available tape and then be distributed in the form of optical discs such as CDs and DVDs later on. However, there exists devices, such as camcorders, that are capable of recording directly on optical media such as DVDs. The Digital8 camcorders are even capable of recording such video onto the conventional analog tapes by way of special encoding techniques. Apart from this, the JVC Everio G camcorders now have the facility to record digital video directly on a hard disk. At present, digital video has seen resolutions as high as 33 mega pixels (7680 X 4320) under test conditions and it is expected to improve further. There exist various formats for encoding and storage of digital video, some of the popular ones being MPEG-1, MPEG-2, MPEG-4, Digital8, MiniDV, HD-DVD and Blu-ray Discs
Image Capture Formats
Video cameras come in two flavors when it comes to image capturing. A video camera may either capture images as interlaced or by way of a progressive scan. These are explained below:
- Interlaced image capture
Interlaced image capture represents the images as a set of alternating lines, quite similar to weaving cloth. The odd-numbered are scanned first followed by the even-numbered lines. This process is done again and again until the whole capture is completed. Each set of odd and even-numbered lines are referred to as ‘field’. A frame is made with the help of the fields. This is done by pairing two fields together, one of them being odd-numbered and the other one being even-numbered.
- Progressive scan image capture
Under the progressive scan technique, the images are scanned per frame, that is, each frame is recorded as a separate, distinct entity. Thus, the two fields of lines may remain the same or equal in two or more frames. This explains the phenomena of a video looking as something which is ‘hyper-real’, as a different image is captured by the camera 60 times per second.
Advantages of Digital Video
Digital video has some distinct advantages over the conventional analog video. These are explained below:
- Quality
Digital video has a very high quality of recording and most importantly, this quality does not fall no matter how many times the video is copied. This is typical of all digital recording, video or audio, and hence is a very big advantage since analog video lost quality after each copy.
- Easier Processing and Editing
Since digital video is stored in a digital format, it is easier to edit and process it as need be. Often, a non-linear editing station or NLE is used for this purpose which is specifically built for digital video and audio editing only. As an added plus, they have the ability of importing data from analog as well as digital sources with no loss of quality in the latter case. Digital video can even be edited on personal computers. However, this requires advanced hardware and software, that is, a high-end system, which has a huge amount of RAM and hard disk space.
- Lower Costs
The biggest advantage of digital video is its low cost. As compared to the conventional 35mm film tape, digital video is very cheap, especially when purchased in bulk. Also, since digital video can be viewed without transferring it to film, it saves expenses on additional tapes to view the video after each edit and detect errors in it. Also, digital video can be easily distributed on optical media and more importantly, over the Internet.
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