formats, standards and codecs

Anna Helme gave an illuminating workshop detailing the basics of how to compress video content for uploading to the web, in particular focussing on video for video distribution/download sites (rather than compressing video for streaming live).

Video sharing archives and networks have arisen over the past few years. One massive site is http://archive.org. It accepts all genres of video (i guess not porn and snuff tho).

A more activista site is http://ngvision.org with a focus on works dealing with social issues, but thers also some more experimental work there such as the "reality fiction" stuff by the Candida TV crew in Rome.

We learnt about formats, standards and codecs.

Formats refer to types of files, for example a video can be digitosed and then saved as a quicktime .MOV (used on apple mac systems, but readable by all), windows .AVI (pc world), MPEG 1. MPEG 4 and so on. A format is like a wrapper - a header and a footer - wrapped around the video file and tells the player what to play.

Standards are sets of rules, how the video is shaped.

We then visited the http://www.doom9.org site which is an excellent resource for sharing information about various codecs.

Codec is short for compression/decompression. A codec is a piece of code that is used by media authoring softwares like the open source Virtual Dub http://virtualdub.org and proprietary Premiere Pro and Final Cut Pro to reduce the size of the video file. This same codec is then used by the media player on your laptop (like quicktime, windows Media Player, Zooom player etc) to decompress your "squashed" video file, making it visible and audible thru the player.

You need to compress video files because uncompressed they are very big. 4 minutes of uncompressed digital video is about 1 Gig of memory.

Different Codecs have their own advantages and disadvantages. In the workshop we first downloaded Xvid, the open source version of the popular amongst P2P ppl DivX codec, from Xvid http://www.xvid.org/downloads.html

When you install this codec both your video editting programs and your players automatically recognise it -- you don't have to put it manually inside these programs.

We also had a quick look at dyne.org, a site which is run by video geeks and activistas which offers some cool video tools and an opensource video editting system.

http://dyne.org

You can download the dynebolic cd from this site

http://dynebolic.org

which is both a linux boot disk and a swag of tools.

The practical

We took a very cool video satirizing a recruiting ad for the Victorian police force. Anna demonstrated how to firstly capture the video from either a VHS video deck, or a Mini DV camera, using the Vegas Studio software from Sonic Foundry.

We then compressed the captured video in another program, Virtual Dub choosing the Xvid codec to squash the image, and the Ogg Vobis codec to squash the audio. The end result was a 17 Mb file compared to the original which was over 200 Mb. The quality was pretty good, and if we had more time we would have played around with the compression options more in Virtual Dub, with a view to making 2 or 3 versions of the video, smaller than our first version, and compressed with a variety of codecs, in order to give potential viewers/users a greater choice in format and file size, depending on their bandwidth connections to the net and what codecs they have installed on their own media players.

Anna discussed the file naming conventions she uses, which make it apparent in the file name which codecs have been used. This is very handy when making your own compression tests, and also if you are uploading different versions of your video to a video distribution site.

eg reclaimstreets-xvid-ogg.mov and reclaimstreets-cinepak-Qmusic.mov

After compressing the video we went to http://archive.org and went through the steps to upload video.

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Link to Index of Oceania Video ImcOceaniaVideo

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-- DollYoko - 18 Jul 2004

• early bonny pirate & video maker: