Tuesday, December 19, 2006

Some things about video codecs

First it was all raw videos. 1 bitmap (image) per frame in the video. But all these bitmaps were stored in the same file.

The people realized there should be an efficient way to store the videos. Some different codecs (coding-decoding standards) were suggested but ultimately Motion Picture Experts Group (MPEG) came to govern the field with their MPEG-I codec (standard VCD).

The frame dimensional limitations (only 352x240 pixels) raised the need for better codecs and there came MPEG-II (640x480 or 720x480 pixels) and introduced us DVDs.

But the file-size was a problem and now different parties came in to the play and broke the monopoly of MPEG. Each such codec supported customizable resolution and drastically reduced the file-size due to high-compression algorithms they used.

Microsoft - WMV/ASF (Windows Media Video)
Apple - MOV (Quicktime Movies)
Vivo Active - VIV
Macromedia - FLV (Flash Video)
and MKV, FLC, etc.

To face this challange MPEG came up with a new codec MPEG-IV (.mp4/ .avi). Yet they could not get back the position they once held due to the popularization of a new codec called DivX.

Following the same nation as DivX some other codecs popped-up with slight differences in the compression algorithms for audio and video. H263, H263+, H264 and MSmpeg4 to name few.

DivX is a proprietor who sells the codec support (not the codec, but the converters etc.) Recently a group of programmers broke from this company and started their own codec based on DivX but offers it completely free. It is spelled reversing the letter order of DivX and called XviD.

Almost all these new high compression video formats carry the extension ".avi" and it is ery difficult to find the exact codec they use without using a "codec info-finder".


Follow these links for more info.
DivX - http://www.divx.com
XviD - http://www.xvid.org/


Due to the hassles caused by so many codecs, many people usually go for a codec-suit and stop worrying about the actual codec a video file needs. These codec-suits install all the required codecs and employs a codec-manager to select the appropriate codecs to play different videos.

I would recommend on K-Lite codec pack as it has a good coverage of codecs. Please visit http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm

There is a good FREE tool that will enable you to convert any popular video format to any other popular video format. Please see http://www.erightsoft.com/SUPER.html. The download link is at the bottom, it will take some time to find it.

You can use this tool to convert your videos to DivX format. One good thing is it supports batch processing.