Creating a Visual Record

• Capturing
•     Disk Space
•     "The Capture": 
•     Transcoding Analog Video to Digital Format using a FireWire Connection
• Editing
•     Why edit?
•     Software Options
• Compressing
•     Why compress?
•     Formats
• Storage

Capturing

Disk Space

Capturing and editing digital video requires a fairly fast (P3-1 GHz / G4-700 MHz processors or faster, with 512MB memory or more) computer with a lot (>40 GB) of hard disk space—one second of video takes about 3.5 MB.  In our experience, a typical 45-minute taping session takes up about 15 GB of space when captured to a hard disk.  (The above specifications are not intended as minimum requirements.  However, working with a less powerful system may be frustratingly slow.)

 The following chart offers more information about space requirements:

(from http://www.dvgear.com/calcharddisksp.html)

Want more info about calculating file size and disk requirements?  Check out Adobe’s site at: http://www.adobe.com/support/techdocs/6076.htm

"The Capture": 

Today, capturing video by using the IEEE 1394 cable (FireWire or iLink) dominates the industry.  This direct digital transfer technology makes capturing video clips easy and FAST.   If your computer does not have built-in FireWire, you can add a FireWire capture card. 

Some popular cards are reviewed here: http://desktopvideo.about.com/library/weekly/aatp_firewire.htm

For additional information about Firewire technology: http://desktopvideo.about.com/cs/firewire/

Though Firewire is now the industry standard in capturing video, analog capture cards can also be used.  For more information about “Getting Video into your Computer: The Not So Easy Way”,  check out  http://desktopvideo.about.com/library/weekly/aa032902a.htm

For more information about popular analog capture cards: http://www.webvideoguys.com/capture.html

Transcoding Analog Video to Digital Format using a FireWire Connection

If you want to convert analog video (VHS, 8mm, Hi8) to a digital format, consider these options:

• Use a digital camcorder equipped with analog line-in recording
• Use a media converter such as the Sony DVMC DA1, or Fastware's DV Playground. 

The media converter and digital camcorder use the same technology and produce identical results. The media converter is less expensive (about $300), but it's only a media converter.  The camcorder option, though more expensive, can  also be used to shoot video.  Our lab uses the Sony Media Converter as our transcoding workhorse, allowing us to keep our cameras available for taping.

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Editing

Why edit?

After video is captured to your hard disk, you may choose to edit your clip(s).  Depending on your specific research purposes, you may decide to

• locate and compile important segments
• rearrange the order of segments
• synchronize different camera views of the same event to show them simultaneously
• add captions, titles
• pretend you're Steven Spielberg and unleash your creative genius

Software Options

Video editors are available in  professional and consumer versions. Generally, the consumer versions are easier to use and less expensive, but also less flexible.

In the professional area, the most popular editor is Adobe Premiere (Windows/Macintosh).  Our lab uses Premiere.  (Note:  Adobe products are available as free trial downloads.) Others in this category include Ulead MediaStudio Pro, inSync Speed Razor, and Apple's Final Cut Pro (Macintosh).

In the consumer area, some of the  leading programs include MGI VideoWave 4, Pinnacle Systems Studio version 7,  and Ulead VideoStudio.

For more information about leading sellers in editing software, check out www.desktopvideo.about.com 

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Compressing

Why compress?

Uncompressed video files are very large.  (One hour of video can take up to 20 GB of hard disk space.)  In order to easily store and disseminate video data, the files must be reduced in size, or compressed.  Video compression can be thought of as the art of throwing away as much data as possible without it being too noticeable.  What comes out after compression isn't identical to what was originally encoded, but today's technology makes it possible to compress files to a manageable size and still maintain high quality images.

Example:  One of our 45-minute tapes takes up approximately 16 GB of hard disk space.  Once compressed to a Realmedia file (sized at 360 x 240), its size is reduced to 150 MB. 

Formats

The four most popular compression formats are Realmedia, Quicktime, Windows Media, and MPEG.  Realmedia, Quicktime, and Windows Media can be used for streaming video, which means that the video can be played while it it being downloaded.  Players for all formats are available as free downloads.

Our lab uses Realmedia because it has good quality and provides the greatest support for SMIL (Synchronized Multimedia Integration Language), which we use for synchronization,  subtitling, and other editing functions.

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Storage

Because of its huge file size, long-term storage of  uncompressed video is impractical for most users.  Once compressed, storage solutions can include dedicated file servers, local hard disks, or CDs. 

In our lab, after we compress video to a Realmedia format (sized at 360 x 240), we can put about 3 hours of video on one CD.  (CD's hold approximately 700 MB of data.) 

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Last revised by Sujai Aug 5,2002

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