Digital Display Standards
- Advanced Television System Committee (ATSC) is the digital television supports wide screen aspect ratio of 16:9 with images up to 1920x1080 pixels in size and a number of other image sizes. It boasts of theater quality because it uses Dolby Digital AC-3 format to provide 5.1-channel surround sound.
- Digital Video Broadcasting (DVB) is used mostly in Europe where the standards define the physical layer and data link layer of a distribution system.
- Integrated Services Digital Broadcasting (ISDB) is used in Japan to allow radio and television stations to convert to digital format.
Overscan And Safe Title Area
- Overscan -
common practice in the television industry to broadcast an image larger than will fit on a standard TV screen so that the "edge" of the image seen by a viewer is always bounded by the TV's physical frame, or bezel. - Underscan-
computer monitors display a smaller image on the monitor's picture tube leaving a black border inside the bezel.
Digital Video
There are many considerations to keep in mind when setting up production environment:
- Computer with Fire Wire (IEEE 1394 or i.Link) connection and cables
- Fast processor(s)
- Plenty of RAM
- Second display to allow for more real estate for your editing software
- Audio mixer to adjust sound output from the camcorder
- External speakers
- Television monitor to view your project (if it's for TV)
- Nonlinear editing (NLE) software
Digital Video Compression
- The overwhelming technological bottleneck is overcome using digital video compression schemes or codecs (coders/coders).
- A codec is the algorithm used to compress (code) a video for delivery and then decode it in real-time for fast playback.
- Real-time video compression algorithms such as MPEG, Indeo, JPEG, Cinepak, and Sorenson are available to compress digital video information.
MPEG
- MPEG standards were developed by the Moving Picture Experts Group, which created standards for the digital representation of moving pictures as well as associated audio and other data.
- MPEG-1 could deliver 1.2 Mbps (megabits per second) of video and 250 Kbps (kilobits per second) of two-channel stereo audio using CD-ROM technology.
- MPEG-2 required higher data rates (3 to 15 Mbps) but also delivered higher image resolution, picture quality, interlaced video formats, multiresolution scalability, and multichannel audio features.
- MPEG-4 provides a content-based method for assimilating multimedia elements. It offers indexing, hyperlinking, querying, browsing, uploading, downloading, and deleting functions, which will enable harmonious integration of natural and synthetic audiovisual objects.
- MPEG-7, called the Multimedia Content Description Interface by integrating information about the image, sound, or motion video elements being used in a composition.
- MPEG-21 provides a "Rights Expression Language" standard designed to communicate machine-readable license information and to do so in a secure manner.
Video recording and Tape Formats
Categories of standards and basic technical difference for choosing the best format for multimedia project.
- Composite Analog Video
- Combines the luminance and chroma information from the video signal.
- It produces the lowest quality video and is most susceptible to generation loss, the loss of quality that occurs as you move from original footage to edit master to copy.
- Component Analog Video
- S-Video (Y/C) - color and luminance information are kept on two separate tracks: (Y/C). The result is a definite improvement in picture quality over composite video.
- Three-Channel Component (Y/R/B-Y,Y/U/V) - divided between luminance (Y) and two channels of chroma, but sometimes divided between the Red/Green/Blue primary additive colors.
- Composite Digital
- Recording formats combine the luminance and chroma information, sample the incoming waveforms and encode the information in binary (0/1) digital code.
- Improves color and image resolution, and having the recording in a digital format eliminates
- Component Digital
- D-l is at the pinnacle of NTSC video and is the mastering standard of choice among high-end editing facilities.
- D-5 is a high quality and uncompressed component digital format.
- DV format takes its samples at smaller bit depths (typically 8 bits) and compresses the video, allowing for the use of smaller tape widths.
Shooting and Editing Video
Adding full-screen, full-motion video to your multimedia project. To produce multimedia that is adequate and does its job using consumer-grade video cameras and recording equipment.
- Storyboarding
- Storyboards are like any sequential comic with three or four panels showing a progression of story or information.
- Structure production by writing it down and then engineer a sequential group of drawings showing camera and scene, shooting angles, lighting, action, special effects and how objects move through from start to finish.
- Shooting Platform
- Using a tripod or even placing the camera on a stable platform, such as a rolled-up sweater on the hood of a car, can improve a shot.
- If shoot handheld, try to use a camera with an electronic image stabilization feature for static shots, a "steady-cam" balancing attachment, or use camera moves and a moving subject to mask your lack of steadiness.
- Croma Keys
- Allow choosing a color or range of colors that become transparent, allowing the video image to be seen "through" the computer image.
- A useful tool easily implemented in most digital video editing applications is blue screen, green screen, Ultimatte, or chroma key editing.
- The technology used by a newscast's weather person, who is shot against a blue background that is made invisible when merged with the electronically generated image of the weather map.
- Composition
- When shooting video for playback from CD-ROM or the Web, it is best to avoid wide panoramic shots.
- Consider also the amount of motion in the shot: the more a scene changes from frame to frame, the more "delta" information needs to be transferred from the computer's memory to the screen, and the slower the playback speed will be.
