Data Size:
- 1 byte is the smallest unit of measure in computer data
- 8 bytes = 1 bit (for example, 1 bit could be the letter "a"
or the number "2 or part of a color)
- 1024 bytes = 1 KiloByte (KB)
- 1024 KB = 1 MegaByte (MB) (1,048,576 bytes)
- 1024 MB = 1 GigaByte (GB) (1,073,741,824 bytes)
Storage Capacities:
- Floppy disks hold 1.44 MB (that is 1,509,949 bytes!)
- CDs typically hold up to 650 - 700 MB (681,574,400 bytes)
- Hard Drives now range from holding 40 GB (42 billion bytes!)
to 200 GB or greater
Size of Digital Video
and image Files:
- 1 minute of video takes up 216MB of hard drive space
- 4.5-5 minutes of video take up 1GB of hard drive space
- An average Photoshop image is around 1.5MB. The same Photoshop
image as a .jpg is 200KB
| Displays
Ratios: (monitors and televisions) |
- Televisions - standard : 4:3 ratio (Examples of this are 640x480;
320x240; 160x120)
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- Television - HD (high definitions) and motion picture: 16:9
ratio
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Video resolution:
Video resolution is a measure of the ability of a video camera
to reproduce fine detail. The higher the resolution the sharper the picture
will look.
The standard NTSC broadcast TV system can potentially
produce a picture resolution equal to about 300 lines of horizontal resolution.
(This is after it goes through the broadcast process. What you see in
a TV control room can be much higher.) CATV, DVD and satellite transmissions
as viewed on a home receiver can reach 400 lines of resolution.
Three- to four-hundred lines of resolution equal what viewers with 20-20
vision can see when they watch a TV screen at a normal viewing distance.
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Video Formats:
AVI - AVI stands for Audio Video Interleave. It is a
format defined by Microsoft, and is the principal file format used by
Video for Windows. QuickTime 3.0+ and DirectX can also play AVI movies.
Many standard codecs and proprietary codecs can be used to compress AVI
movies.
QuickTime - Because free players are available for virtually
any operating system, QuickTime is the most popular video format in use
today and has recently been selected by the International Standards Organization
as the basis for the future MPEG-4 specification. One of QuickTime's greatest
strengths is its support for multiple data tracks, making possible the
use of multiple video, audio, MIDI, text, and sprite tracks. On Power
Mac computers, the QuickTime MPEG extension also allows for software decompression
of MPEG files.
MPEG (MP3) - There are two different MPEG standards
commonly in use.
- MPEG-1 is used for 352x240, l5fps video running at about 45-350 KB/second
(note, however, that many MPEG decoders are designed to work only at
160 KB/sec and performance may suffer badly otherwise).
- MPEG-2 uses 720x480, 30fps video at 50OK13-2MB/second.
- MPEG- I is best for CD-ROM delivery because of its relatively low
data rate.
- MPEG-2 was originally designed for broadcast quality video delivered
via high bandwidth connections. DVD and DSS satellite television both
use MPEG-2 compression.
Streaming Video Formats
A number of streaming video formats are currently in use for web-based
video, with QuickTime(4) starting to become dominant. Others include:
RealVideo, VDOLive, Vivo, and Streamworks. Since Internet bandwidth varies
so greatly, these systems either drop frames or the entire video track
when bandwidth drops below an acceptable level. They all require proprietary
encoding and decoding software.
Source: http://www.mtholyoke.edu/lits/csit/mellonweb/oldswebtech/aubrey/digvid2.html
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