As technology advances, powerful processors, bigger hard drives, and faster internet connection speed, many people may think that compression would be out of date. This is a totaling wrong and a myth. Compare to text, word document, audio and video files take much larger space, and cost much more bandwidth all together. Without compression and appropriate encoding and decoding, enjoying streaming video and audio without stuck would be impossible and would cost you a lot of money on extra storage and bandwidth.
Generally Speaking, there are two ways of compression, one is compression with loss, and the other is lossless compression.

About Loss Compression:

Loss compression literally means that compress the video or audio file with some damages on the original data. This kind of compression would delete the redundant information for ever, meaning that not all the data of the original file can be saved. This does not mean that loss compression can not produce quality video and audio. Appropriate compression with loss can also produce video and audio that are nearly indistinguishable from the original files with human eye and ear.

About Lossless Compression:

Lossless Compression does not mean that the file is compressed without damage of data at all. This is “Lossless” is a relative definition to loss compression. Lossless compression reduces the audio and video file size by only 50-60%. Uncompressed AVI files are of huge size and will take a lot of storage. Compression of AVI or AVI Codecs greatly reduces the file size without damaging the quality of video. AVI’s popularity and extensibility depend on the fact that you can freely select different video and audio codecs. With AVI, you can just switch to a better codec. The Windows Media format (WMV) also uses codecs, but fewer of them and the selection process is hidden from the user. You just have to select an appropriate profile and the profile will automatically select a codec. While the process of making an AVI file lets you choose among up to dozens of different codecs, you face the challenge of selecting the right codec. Video Converter enables you to control the frame rate, the video resolution and the key frame rate, and to choose the audio and video compressors when creating AVI files. If you have a bunch of DVDs and want to convert DVD to AVI for further editing, you can try Pavtube DVD Ripper.
Many AVI compressors, tailored for different needs, have been designed. For our purpose, the key things to know are the quality of the video playback and the compression ratio for each codec. Which compressor to choose depends on the intended use of the file and the desired output quality? Many codecs can be downloaded directly from the Internet.

CINEPAK:

This is file format that wraps a Cinepak video bitstream with other data chunks, e.g., audio. Multiple versions of Cinepak exist, including SuperMac, Radius, and Compression Technologies; this document does not distinguish between them. Used as a middle-state format (often used as the video source when producing lower-resolution streaming versions); also used as a final-state format for enduser delivery.

MICROSOFT MPEG-4 VIDEO:

MPEG is a standard defined by the Moving Pictures Experts Group. There are many codecs complying with the MPEG 4 standard, including ones from leading manufacturers like Apple, Ligos, DivX, etc. The Microsoft MPEG-4 codec gives high quality compressions, is easy to use and enjoys good compatibility.

MICROSOFT VIDEO 1:

This is a popular codec bundled with all versions of Windows. Microsoft Video 1 provides excellent video quality and reasonable compression ratio.

AVI MJPEG

This is a video adaptation of the JPEG standard for images. It is ideal for editing and video capture. Many editing systems are built around MJPEG. One major advantage is that compression is fast and can be carried out in real time. However, there are many implementations of MJPEG, raising compatibility issues among videos compressed by different systems.
DivX:

This MPEG-4 compliant codec provides high quality compression. The codec boasts offers support for multiple languages, good visual quality, speed and compression. However, users have reported synchronization issues. Users have also reported compatibility problems amongst files compressed using different versions of DivX.

Xvid

XviD is a MPEG-4 compliant video codec designed to compress and decompress digital video. It is designed as an Open Source alternative to DivX.


Related Article: How to Convert DVD to AVI

2009 - 02 -16