Communication outline
Com 261 Lesson 02
Video signal color
A video signal color is made up of Red, Green and Blue colors on the spectrum.
Scanning process
1. Interlaced scanning
2. Progressive scanning
Interlaced scanning
1. Frame=field 1+field 2
A field is an odd or even vertical line of video.
2. Refresh rate=the number of frames scanned each second , fps.(每秒钟扫过的frame数)
Progressive scanning
All vertical lines are shown with each scanning cycle.
Aspect ratio (画面长宽比)
1. Width to height of the tv screen
2. Standard TV: 4*3
3. HDTV: 16*9
All digital systems are based on the off/on principle of binary code.
1. On state=1
2. Off state=0
Sampling
1. A number of voltages are taken a different interval. Sampling is basically analyzing the analog video.
2. The higher number of instances at short intervals gives a high sample rate.
3. Higher sampling rate=better images.
4. 在同一个short interval中，sample越多，图像越逼真。
如同每秒16次sample比每秒8次更逼真
Compression 压缩
Compression is the temporary rearranging or eliminating of all data that is not necessary to maintain the quality of video or audio for transport or storage.
1. Lossless compression=dosen’t throw away any info, just rearrange it.
2. Lossy compression=eliminates any info that is redundant (can reduce image quality). 例子：MP4
3. Codecs=compression/decompression systems that change the ways files compressed.
Compression
1. Downloading
The info is packaged out of order and must take time to assemble before you can view or listen to it.
2. Streaming
The info is in order and therefore you can view/listen to the first part of the file while the rest is still being delivered.
Frame rates
1. =the number of frames scanned per second
2. can be changed in digital video
3. Film: 24 fps (realness小)
4. Video: 30fps (realness大)
5. Some cameras can shoot a variety of frame rates.
Flat panel displays
1. LCD Screen (Liquid crystal display)
Uses a thin layer of liquid with crystal molecules that change when
Video signal color
A video signal color is made up of Red, Green and Blue colors on the spectrum.
Scanning process
1. Interlaced scanning
2. Progressive scanning
Interlaced scanning
1. Frame=field 1+field 2
A field is an odd or even vertical line of video.
2. Refresh rate=the number of frames scanned each second , fps.(每秒钟扫过的frame数)
Progressive scanning
All vertical lines are shown with each scanning cycle.
Aspect ratio (画面长宽比)
1. Width to height of the tv screen
2. Standard TV: 4*3
3. HDTV: 16*9
All digital systems are based on the off/on principle of binary code.
1. On state=1
2. Off state=0
Sampling
1. A number of voltages are taken a different interval. Sampling is basically analyzing the analog video.
2. The higher number of instances at short intervals gives a high sample rate.
3. Higher sampling rate=better images.
4. 在同一个short interval中，sample越多，图像越逼真。
如同每秒16次sample比每秒8次更逼真
Compression 压缩
Compression is the temporary rearranging or eliminating of all data that is not necessary to maintain the quality of video or audio for transport or storage.
1. Lossless compression=dosen’t throw away any info, just rearrange it.
2. Lossy compression=eliminates any info that is redundant (can reduce image quality). 例子：MP4
3. Codecs=compression/decompression systems that change the ways files compressed.
Compression
1. Downloading
The info is packaged out of order and must take time to assemble before you can view or listen to it.
2. Streaming
The info is in order and therefore you can view/listen to the first part of the file while the rest is still being delivered.
Frame rates
1. =the number of frames scanned per second
2. can be changed in digital video
3. Film: 24 fps (realness小)
4. Video: 30fps (realness大)
5. Some cameras can shoot a variety of frame rates.
Flat panel displays
1. LCD Screen (Liquid crystal display)
Uses a thin layer of liquid with crystal molecules that change when