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How do I compress a video file for the web?
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Last Updated
2nd of September, 2008

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Video Compression

Uncompressed video files are too large to be used on the web. For example, standard uncompressed NTSC video (720 x 480) has a data rate of about 27 Mb / second. At this rate, 46 seconds of video would fill an entire Advanced Hosting account, and if it we viewed about one time per day, use your entire mothly data transfer. A T1 offers a data transfer rate of 1.5 Mb / second and the fastest broadband providers off downstream speeds of up to 8 Mb / second, neither of which come close to the 27 Mb / second transfer rate required for uncompressed video.

Video Compression vs. Video Encoding

In order to deploy video on the web, we need to compress it. To make it readable by our browsers, it will also be encoded into a format that a browser plugin can read. The algorithm used to compress the video (or audio) is provided by a CODEC, or COMpressor/DECompressor. Most high-quality CODECS available today will produce high-quality video while cutting the file-size by more than 1/10th its original size. Usually we will also reduce the width / height of the video file to further reduce its file size (for example from 720 X 480 to 320 x 240 pixels). Bear in mind that the CODEC (used for compression) and encoding (defines which types of players can play the media file) are separate. For example, a media file can be compressed using the Sorenson Video 3 in either Quicktime of Flash format. If I encode the file using Quicktime, a user without the Quicktime application will be unable to play the media file, even if they have the Sorenson Video 3 CODEC installed on their computer.

Proprietary CODECS

In addition to encryption, CODECS can also provide protection and encryption. For example, MPEG-2 (used to compress DVDs) also provides encryption and write-protection. The viewer has an MPEG-2 CODEC installed that allows them to view the video, but not to edit it. The Sorenson Video 3 CODEC adds a Media Key feature that can protect the file from being viewed without access to a media key.

Compressing your Video Files

If you are using a video editing program, you will have several options of encodings and CODECS to use when you render the video. If you are looking for a wider variety of options in terms of video compression and encoding, you could look at some of the following stand-alone applications:

1. Sorenson Squeeze - Video Compression / Encoding software with support for multiple CODECS and Flash (.swf and .flv), Quicktime, Windows Media, and Real encodings

2. Flash Video Encoder - Support for Flash-based video encoding only (.swf and .flv).

3. Quicktime Pro - Support for Quicktime encoding only. You must purchase the Pro version to encode / compress video. The free Quicktime download is only a player.

4. Windows Media Encoder - Support for Windows Media encoding only (but free for licensed Windows users.

5. Real Media Producer - Support for Real Media encoding only.

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