1. DVDRip（Divx）
DVDRip is media format, with DVD video hige quality compressed by using Divx technology, while of DVD audio compressed by MP3 or AC3, and then to combines audio and video as AVI(audio video interleaved), at last adding subtitle documents to form the new Divx format. It has a quite samll volume around hundreds MB, which is very convenient to collect.

2. RMVB
RMVB format is upgraded from RM films. VB means VBR, short for variable bit rate. It is different from the original way of using average compress. Based on the average compress rate, VB has made the best usage of Bit rate resource, which compresses the filem volume in the most limitation on by sacrificing little film quality that makes it close to DVD quality perfectly.
Compared with DVDRip, RMVB has much more advantages. Firstly, the volume of RMVB is only 300MB-450MB (to calculate in the standard of 90 minutes film) but of good A&V effect. On the contrary, DVDRIP need 700MB or even more. Secondly, RMVB has lots of advantages, like with built-in subtitle, without support of external software, low occupation in display system and so on. All these make it become the mainstream format in the nowadays network films. 

3. MKV
MKV is to be considered as future mainstream media format. Actually it is a new multimedia seal format, to be named as multimedia container as well. It is different from DIVX and Xvid video coding format as well as MP3 and Ogg audio coding format. MKV just provide shell’s “combination” and “seal” format for these audio and video. In another word, it is a container format. The ordinary AVI, VOD, MPGE and RM formats are also this type. But they are either out-dated in structure or not open enough. All these reasons facilitate the birth of multimedia container like MKV.
The main character of MKV is to contain many different kinds of coding video, audio and subtitle stream, or even of much closed Real Media and QuickTime media. It’s a huge media container. But the shortcomings are with much occupation, high in rate so it is not satisfactory to display online. 

4、AVI
AVI is the usually called DVD version, with volume of a film around 700M-1.5G. However, it is the best quality film with all kinds of options of DVD, except high definition ones.Basically when the newest movie is on, there will be its AVI format on internet in 3 month. 


1080i

1080i means that the resolution of the picture is 1920 vertical pixels by 1080 horizontal pixels and i stands for interlaced scanning. Interlaced scanning is based on the principle that the screen shows every odd line at one scan of the screen and then all the even lines in a second scan.

1080p

1080p means that the resolution of the picture is 1,920 vertical pixels by 1,080 horizontal pixels and p stands again for progressive scanning. This format works on the same principle as 720p; the only difference is that in this type there are more pixels and the resolution is better.

720p

720p means that the resolution of the picture is 1,280 vertical pixels by 720 horizontal pixels and p stands for progressive scanning. Progressive scanning offers a smoother picture as 720 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second. 



Bandwidth

Bandwidth, in general, means amount of information that can be carried in a given time period (usually a second). More exactly, it is a range of frequencies used for transmitting picture and sound information from transmitter to your TV. Federal Communications Commission (FCC) has allocated 6 MHz for TV broadcasters for each channel. 

Bit Rate

Bit rate is measured as "bits per second" (bps) and refers to the rate at which the data is transmitted. For Digital TV, the maximum possible bit rate within the bandwidth is 19.4 Mbps while SDTV has a lower bit rate. The higher the bit rate, the more data is processed which usually results to higher picture resolution or better sound quality. 

Codec

Codec is a short term for “Coder-decoder.” This device is used to convert analog video and audio signals into digital format, and vice verse, it can also convert received digital signals into an analog format.

Dolby Digital (Dolby AC-3)

Dolby Digital, also called Digital 5.1 or AC-3, is a five-channel surround sound system which delivers CD-quality digital audio and provides five channels of full frequency for front left, front right, center, surround left and surround right speakers, plus one channel for LFE (low frequency effect) subwoofer. It is the official audio standard for Digital TV and HDTV. 

16:9
16:9 is aspect ratio of movie screen and widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height. 

4:3
4:3 is aspect ratio of traditional squarish National Television Systems Committee (NTSC) TV screens; it stands for four arbitrary units of width for every three arbitrary units of height. 

DTV (Digital Television)

DTV stands for Digital Television. It refers to all digital television formats and standards established by the Advanced Television Systems Committee (ATSC). Two basic DTV standards are HDTV (high-definition television) and SDTV (standard-definition television) 

EDTV (Enhanced-Definition Television)

EDTV stands for Enhanced Definition Television. The picture quality of EDTV is superior to that of standard analog TV (480i) but not as good as HDTV (1080i or 720p). EDTV displays the picture at a resolution of 852x480 (480p) lines in either 4:3 or 16:9 aspect ratios and it includes Dolby Digital sound system.

LCD (Liquid Crystal Display)

LCD stands for Liquid Crystal Displays. It refers to a flat panel technology which uses liquid crystals sandwiched between two glass plates for example in laptop computers, other small portable displays and also in televisions. Wide-screen HDTVs are available with displays of adequate resolution up to about 37 inches. 

NTSC (National Television Systems Committee)

NTSC or National Television Systems Committee is the organization that develops technical standards for black-and-white television and color television. The term is also used to refer to the video-transmission standard used in the western hemisphere, Japan, and other Asian countries. NTSC established the 525-line (480 visible) analog broadcast TV standard. It is supposed to be soon replaced by digital broadcast standards.

Pixel

Pixel comes from the words “picture element” and it refers to the smallest element in a television picture. Pixels are single displayable video dots from which the overall picture is made up. 

Plasma Displays (PDP)

Plasma display is created by thousands of tiny tubes filled by ionized gas in a plasma state. Ionized gas is very light and flat panel TVs made by this technique can be even hanged on the wall! Plasma displays offer excellent resolution and color and they are the most suitable for the home theatre. 

Resolution

Resolution reflects the density of lines, and dots per line which make up a visual image. It is measured by the number of pixels displayed. The level of resolution directly affects picture quality. Usually the higher number of lines and dots means also sharper and more detailed picture. Analog TV has a little over 200,000 color pixels while HDTV, with 1080 vertical pixels and 1920 horizontal ones, has more than 2 million pixels creating the image. 

SDTV (Standard-Definition Television)

SDTV stands for Standard Definition Television. The SDTV picture, having either in 4:3 or 16:9 aspect ratios, is better and of higher quality than the one of NTSC, however, it does not reach the quality and resolution of HDTV. SDTV is based on 480 lines of vertical resolution and in both interlaced and progressively scanned formats. 

Flat-panel TV

Flat-panel TV typically displays picture using gas plasma or LCD technology and is only a few inches thick. 

Front-projection TV

Front-projection TV comprises 2 parts – a separate front projector (usually placed on a table or ceiling-mounted) and a reflective screen (or simply a wall). The projector is placed at one end of the room, the screen is at the other end, and the speakers may be placed wherever they will provide you good sound experience. The picture can be rather large but remember – the larger the picture, the more visible the pixels or scan lines and the darker the image.

HDTV (High-Definition Television)

HDTV stands for High Definition Television. This highest-resolution subset of Digital Television offers filmlike picture quality with impressive surround sound. With twice the vertical and horizontal picture resolution, the picture of HDTV is approximately twice as sharp as that of NTSC. HDTV has widescreen aspect ratio of 16:9 and Dolby Digital sound system. Currently used HDTV formats - 1080i and 720p both offer reduced motion artifacts like ghosting and dot crawl. 

Set-top Box (STB)

Set-top box is responsible for receiving, converting and sending the picture and sound of the broadcast to the associated television. If your HDTV-ready TV has no built-in HDTV tuner you must connect it to a compatible HDTV STB first. Until then it will not receive and display digital television programs. 

Widescreen                                                                           

Widescreen TV is the television with 16:9 aspect ratio. 16:9 is the aspect ratio of movie screen and widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height.

IEEE 802.11

In 1997, the Institute of Electrical and Electronics Engineers (IEEE) created the first WLAN standard. They called it 802.11 after the name of the group formed to oversee its development. Unfortunately, 802.11 only supported a maximum network bandwidth of 2 Mbps - too slow for most applications. For this reason, ordinary 802.11 wireless products are no longer manufactured.

IEEE 802.11b

802.11b uses the same unregulated radio signaling frequency (2.4 GHz) as the original 802.11 standard. Vendors often prefer using these frequencies to lower their production costs. Being unregulated, 802.11b gear can incur interference from microwave ovens, cordless phones, and other appliances using the same 2.4 GHz range. However, by installing 802.11b gear a reasonable distance from other appliances, interference can easily be avoided.

• Pros of 802.11b - lowest cost; signal range is good and not easily obstructed
• Cons of 802.11b - slowest maximum speed; home appliances may interfere on the unregulated frequency band

IEEE 802.11a

802.11a supports bandwidth up to 54 Mbps and signals in a regulated frequency spectrum around 5 GHz. This higher frequency compared to 802.11b shortens the range of 802.11a networks. The higher frequency also means 802.11a signals have more difficulty penetrating walls and other obstructions.

Because 802.11a and 802.11b utilize different frequencies, the two technologies are incompatible with each other. Some vendors offer hybrid 802.11a/b network gear, but these products merely implement the two standards side by side (each connected devices must use one or the other).

• Pros of 802.11a - fast maximum speed; regulated frequencies prevent signal interference from other devices
• Cons of 802.11a - highest cost; shorter range signal that is more easily obstructed

IEEE 802.11g

• Pros of 802.11g - fast maximum speed; signal range is good and not easily obstructed
• Cons of 802.11g - costs more than 802.11b; appliances may interfere on the unregulated signal frequency

IEEE 802.11n

When this standard is finalized, 802.11n connections should support data rates of over 100 Mbps. 802.11n also offers somewhat better range over earlier Wi-Fi standards due to its increased signal intensity. 802.11n equipment will be backward compatible with 802.11g gear.

• Pros of 802.11n - fastest maximum speed and best signal range; more resistant to signal interference from outside sources
• Cons of 802.11n - standard is not yet finalized; costs more than 802.11g; the use of multiple signals may greatly interfere with nearby 802.11b/g based networks.