| AVI Format | | | | RM format developed by RealNetworks |
| The AVI format whose full name is "Audio | | | | Corporation is a video format for stream |
| Video Interleaved" is very familiar to | | | | media. It includes RealAudio, RealVideo |
| peoples. This format is widely used in | | | | and RealFlash. To transmit and play |
| daily life, and its video quality is | | | | real-time video files in |
| superior, while there are also many | | | | narrow-bandwidth Internet, Real Media |
| defects such as its large size, which | | | | adopts distinct compress rate according |
| takes too much hard-disk to store. | | | | to the bandwidth. RealVideo is used to |
| In 1992, Microsoft corporation developed | | | | transmit video data. Except being played |
| the AVI video format, which is known by | | | | as a normal video file, it also can be |
| people with Windows3.1. Namely "Audio | | | | used together with RealServer. |
| Video Interleaved", the AVI file | | | | RealEncoder converts real-time video to |
| interleaves video and audio data and | | | | RealMedia Format, which is broadcasted |
| play them together. One of the advantage | | | | by RealServer. You can enjoy the video |
| of AVI file is it can be used and played | | | | when you are downloading it. Not like |
| in different platforms. In another hand, | | | | many other video format, it is not |
| to achieve the good quality, its file | | | | necessary for RM format to download the |
| size is too large. Even worse, there are | | | | whole video file before it can be |
| many different compression standards so | | | | played. |
| that some AVI files can not be played if | | | | Currently, many websites provide |
| the system does not contain a proper | | | | RealVideo files. You can use RealPlayer |
| codec. In order to play a AVI, | | | | or RealOne Player to play videos |
| sometimes, you have to download newer | | | | compressed by RealMedia technology. |
| codec updates and that is very | | | | Another important feature of the format |
| inconvenient. | | | | is video files can be played without |
| MPEG Format | | | | downloading, if you use RealPlayer or |
| The full name of MPEG is ?Moving Picture | | | | RealOne Player. |
| Expert Group?, which is an international | | | | RMVB Format |
| compression standard designed for moving | | | | As the heir of RM format, RMVB format is |
| images. MPEG algorithms compress data to | | | | developed based on RM format. The |
| form small bits that can be easily | | | | advantage is RMVB format abandons |
| transmitted and then decompressed. | | | | Average Bit Rate and use Variable Bit |
| Redundancy between subsequent images and | | | | Rate to compress video data. By Variable |
| previous images is removed while most | | | | Bit Rate technology, quality of video |
| similar parts are preserved to cut down | | | | files is greatly improved while file |
| the file size. Its compression rate can | | | | size of them is acceptable. |
| reach 50:1 and it is a video standard of | | | | DivX Technology |
| good compatible. Currently, MPEG | | | | DivX developed by DivX, Inc. is a |
| includes three compression standards: | | | | popular new video compression |
| MPEG-1, MPEG-2 and MPEG-4. Additional, | | | | technology, which enables users to |
| MPEG-7 and MPEG-21 are being developed. | | | | create and play high-quality videos in a |
| MPEG-4 Format | | | | fast and convenient way. For its |
| MPEG-4 (MP4) is a moving picture | | | | outstanding quality, the DivX codec is |
| compression standard which is used for | | | | one of the most popular MPEG-4 based |
| Internet, broadcast, and on storage | | | | codec. It integrates MPEG-4 and MP3 |
| media. Relative to MPEG-2, MPEG-4 | | | | technology, namely it adopts DivX |
| provides improved quality at a small | | | | technology to compress DVD video data, |
| size. Not only can it be used in narrow | | | | while MP3 or AC3 is used to compress |
| bandwidth but also in wide bandwidth. | | | | Audio. The quality is so superb that |
| Currently, the most compression | | | | there is only a little disparity between |
| technology of MPEG4 are DivX and XviD. | | | | DivX videos and DVDs. Another remarkable |
| Videos processed by DivX or XviD lose a | | | | advantage is compared to DVDs, DivX |
| little quality but the size will be | | | | videos provide the same image quality at |
| reduced greatly. It provides users a | | | | only 1/10 the size. Especially, it is |
| convenient way to store a movie in a | | | | suitable for movie downloads. In a word, |
| common CD-Rom disc, while the quality is | | | | this video format is very popular and |
| better than VCD obviously. | | | | liked by many movie fans. |
| RM Format | | | | |