A helpful guide for Digital and Internet Video Producers

A Multi-part series of articles
By Lorraine Grula - Internet Video Gal

Part 3 - The H26L Series of Codecs

Internet video intimidates lots of folks because there’s so much technical jargon it’s like an alien language.  Fear not video enthusiasts! 

The video experts at http://videoproductiontips.com have compiled this helpful guide to help you wade through it all.  This is the third in a multi part series that explains all the technical mumbo-jumbo you need to know in order to enjoy producing, sharing and watching Internet video files.

In this article, we’re going to talk about the H.26L series of codecs developed jointly in a partnership of the Video Coding Experts Group, (VCEG) and MPEG, the Motion Picture Experts Group. MPEG)  Those two groups based the H.26L series on earlier developmental work from the International Telecommunications Union based in Geneva, Switzerland.  

The current version of the series, H.264, is an important element of many software applications.  It is not a file format unto itself.

H.261 was the first version designed for transmission of video over Integrated Services Digital Network (ISDN) lines on which data rates are multiples of 64 kbit/s.

H.261 was considered a break-through technology.  The basic processing unit of the design is called a macroblock, and H.261 was the first standard in which the macroblock concept appeared.

One advantage of H.261 was an effective post-processing technique that became a key element called the de-blocking filtering. This reduced the appearance of annoying block-shaped artifacts caused when motion is compressed.   Such block-like pixilations are probably familiar to almost everyone who has watched digital video.

Deblocking filtering has since become an integral part of the most recent standard, H.264 (although even when using H.264, additional post-processing is still allowed and can enhance visual quality if performed well).

H.261 has become essentially obsolete, although it is still used as a backward-compatibility mode in some video conferencing systems and for some types of internet video.

H.263 is the second in this series designed by the ITU-T.  H.263 came in 1996 as a low-bitrate compressed format for video conferencing and internet transmission.  

The next enhanced codec developed by this consortium is the H.264 standard, also known as AVC and MPEG-4 part 10.   It was completed in May 2003.  This version is the most up-to-date and H.264 provides a significant improvement beyond H.263.   Most new videoconferencing products now include H.264 but remain compatible with H.263 and H.261. 

This is the end of part 3 of this guide to digital video file formats.

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