by Logan Sanderson

Created on: May 15, 2009   Last Updated: May 18, 2009

When attempting to compress a video to a smaller size, whether it be for easy distribution, or to reduce disk space usage, you must ask yourself a few questions:

1) How much quality am I willing to sacrifice to make this video smaller?

2) How much time do I have to compress this video?

3) What kind of audience will be watching this video?

The video format you choose depends on the answers to these three questions.

In contrast to lossless compression formats used for file archives, like ZIP, video compression is lossy. When you compress a video, some amount of quality is lost. However, some video compression algorithms are better than others, and can compress video with less loss for the same file size; but these algorithms are usually slower. Another factor to consider is support, as some formats may not be playable without additional software.

H.264/MPEG-4 AVC is a popular, high-quality, and widely supported format. H.264 format can be played in QuickTime player as well as many other popular video players (such as VLC or Media Player Classic) as long as the user has the necessary decoders installed. At lower bitrates, the H.264 codec can be used in iPods and PSPs (with some special parameters). H.264 is usually combined with the AAC audio codec. The downside is, that x264 is one of the slowest encoders.

XviD/DivX is also popular and has quality similar to H.264. XviD is much faster than H.264, but is less supported. Generally, most portable media players will not play XviD. However, most software video players than can play H.264 will also be able to play XviD and DivX. XviD may be combined with the MP3 audio format.

Windows Media Video is another popular codec mainly because it is packaged with Microsoft Windows. WMV has decent quality, but not as good as XviD or H.264. The advantage of WMV is that users of Microsoft Windows will not need any special software to play videos encoded in WMV format. The WMV format is always accompanied by the Windows Meida Audio format (WMA).

MPEG-1 and MPEG-2 formats are older and, despite the fact that they are very fast and well supported, their file sizes are generally much larger than the three codecs mentioned above. MPEG-2 is useful for DVDs or video editing; but not as useful for storage or transport. MPEG-2 videos will usually be combined with MP2 audio compression.

Now, you must decide how much you would like to compress the video. Higher bitrates yield better quality, but also larger file

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