working with digital video in the classroom jim demmers georgia tech research institute

Working with Digital Video Working with Digital Video in the Classroomin the Classroom

Jim DemmersJim Demmers

Georgia Tech Research InstituteGeorgia Tech Research Institute

Digital VideoDigital Video

So what is digital video?So what is digital video?• It can be a variety of things:It can be a variety of things:

• A movie on DVDA movie on DVD• A home video stored on tapeA home video stored on tape• A QuickTime movie trailer on the WebA QuickTime movie trailer on the Web

• Digital video is stored as a series of ones and zerosDigital video is stored as a series of ones and zeros

How is it different from analog video?How is it different from analog video?• Capture digital video - digitize analog videoCapture digital video - digitize analog video

• Capturing is akin to copying a computer file - each generation is Capturing is akin to copying a computer file - each generation is virtually identical to the parentvirtually identical to the parent

• Digitizing samples a fluctuating voltage signal at discreet intervals, Digitizing samples a fluctuating voltage signal at discreet intervals, which adds generation losswhich adds generation loss

• As long as the video stays digital it doesn’t lose any integrityAs long as the video stays digital it doesn’t lose any integrity

Video CaptureVideo Capture

Some things you need to know:Some things you need to know:• Types of video signalsTypes of video signals

• Composite, S-Video, Component YUV and RGB, FireWireComposite, S-Video, Component YUV and RGB, FireWire

• Start with the best video source availableStart with the best video source available• VHS - 8mm - Hi-8/S-VHS - Beta SP/MII - DV/DVCPROVHS - 8mm - Hi-8/S-VHS - Beta SP/MII - DV/DVCPRO

• Avoid generation lossAvoid generation loss• Keep your frames cleanKeep your frames clean• Be aware of Gamma differencesBe aware of Gamma differences• Purchase a fast A/V hard drivePurchase a fast A/V hard drive• Keep your capture drive defragmentedKeep your capture drive defragmented


Hard disk storage for videoHard disk storage for video• Ultra ATA vs Ultra2 SCSI drivesUltra ATA vs Ultra2 SCSI drives

• ATA is fast and cheap nowATA is fast and cheap now

• Drive specificationsDrive specifications• sustained transfer speed at least 8 MB/sec sustained transfer speed at least 8 MB/sec • seek time less than 9 msseek time less than 9 ms• spindle speed at least 5400 rpmspindle speed at least 5400 rpm

• How much space do you need for Digital video?How much space do you need for Digital video?• Data transfer rate for DV-format video is 3.6 MB/sec Data transfer rate for DV-format video is 3.6 MB/sec • 3.6MB/sec * 60 sec = 216 MB/min = 13 GB/hour3.6MB/sec * 60 sec = 216 MB/min = 13 GB/hour• Multiply by 5 (for project, render & test files) = 1 GB/minMultiply by 5 (for project, render & test files) = 1 GB/min


Digitizing analog video requires an A/D converter or Digitizing analog video requires an A/D converter or capture cardcapture card

• Good choices in A/D converters are:Good choices in A/D converters are:• Sony DVMC-DA2Sony DVMC-DA2• Dazzle Multimedia’s DV-BridgeDazzle Multimedia’s DV-Bridge• Formac StudioFormac Studio• Power R Director’s CutPower R Director’s Cut

• Good choices in capture cards for the PC are:Good choices in capture cards for the PC are:• Pinnacle Studio DVPinnacle Studio DV• Canopus DV RaptorCanopus DV Raptor

Post ProductionPost Production

Linear vs non-linear editingLinear vs non-linear editing• Linear editing copies shots from one video storage media Linear editing copies shots from one video storage media

to another in sequenceto another in sequence• Non-linear editing uses a computer hard drive as random-Non-linear editing uses a computer hard drive as random-

access storage mediaaccess storage media

Most non-linear editors are also non-destructiveMost non-linear editors are also non-destructive• you can change or delete captured clips without affecting you can change or delete captured clips without affecting

the original source clipthe original source clip

Non-linear editing ToolsNon-linear editing Tools• Premiere (Mac/PC), Final Cut Pro, iMovie (Mac)Premiere (Mac/PC), Final Cut Pro, iMovie (Mac)

Post ProductionPost Production

So what’s it take to put together a good DV capture and editing So what’s it take to put together a good DV capture and editing system?system?

• A computer with a fast processor and lots of RAMA computer with a fast processor and lots of RAM• 60 to 90 GB of fast hard disc storage60 to 90 GB of fast hard disc storage• A video capture card or native firewireA video capture card or native firewire• A non-linear editing program A non-linear editing program • Recording equipment (VTR/DVCR, CD-R or DVD drive)Recording equipment (VTR/DVCR, CD-R or DVD drive)

And all of this for under $2500And all of this for under $2500

Video CompressionVideo Compression

Why compression?Why compression?• bandwidth and playback limitationsbandwidth and playback limitations

Video compression/decompression requires a codecVideo compression/decompression requires a codec• software/hardware technology that reduces the amount of software/hardware technology that reduces the amount of

information within individual video framesinformation within individual video frames

Factors that effect video compression Factors that effect video compression • bit depth - number of colors displayedbit depth - number of colors displayed• frame size - number of pixels used to store each frameframe size - number of pixels used to store each frame• frame rate - number of video frames captured/played per frame rate - number of video frames captured/played per

secondsecond


3 primary criteria to consider when selecting a codec3 primary criteria to consider when selecting a codec• Compression levelCompression level• Quality of compressed videoQuality of compressed video• Compression/Decompression speedCompression/Decompression speed

It’s during the decompression process that codecs It’s during the decompression process that codecs display their strengths and weaknessesdisplay their strengths and weaknesses

Video compression toolsVideo compression tools• Cleaner 5Cleaner 5• QuickTimeQuickTime

Video Compression

Legacy codecsLegacy codecs• Cinepack (Web/CD-ROM)Cinepack (Web/CD-ROM)• Photo JPEG (Web)Photo JPEG (Web)• Apple Video (CD-ROM)Apple Video (CD-ROM)• Animation (Web/CD-ROM)Animation (Web/CD-ROM)• Graphics (Web/CD-ROM)Graphics (Web/CD-ROM)

Modern codecsModern codecs• Sorenson Video (Web/CD-ROM)Sorenson Video (Web/CD-ROM)• On2 VP3 (Web/CD-ROM)On2 VP3 (Web/CD-ROM)• MPEG-2 (DVD-video)MPEG-2 (DVD-video)• MPEG-4 (Web)MPEG-4 (Web)• Real G2/RealVideo 8/9 (Web)Real G2/RealVideo 8/9 (Web)


Legacy codecsLegacy codecs• Cinepack (Web/CD-ROM)Cinepack (Web/CD-ROM)

• Good for medium quality CD-ROM videoGood for medium quality CD-ROM video• Extremely low CPU requirements - works well on older computersExtremely low CPU requirements - works well on older computers• Built into MS Video for Windows and QuickTimeBuilt into MS Video for Windows and QuickTime• Lower quality than many other codecs at the same data ratesLower quality than many other codecs at the same data rates• Doesn’t produce good results at Web data rates (below 30KBps)Doesn’t produce good results at Web data rates (below 30KBps)

• Photo JPEG (Web)Photo JPEG (Web)• Used for still images & editing and storage of high-quality video filesUsed for still images & editing and storage of high-quality video files• Built into MS Video for Windows and QuickTimeBuilt into MS Video for Windows and QuickTime• Good choice for low-data rate slide show moviesGood choice for low-data rate slide show movies• Not well suited for CD-ROM or higher data ratesNot well suited for CD-ROM or higher data rates• Other codecs are better suited for Web-based videoOther codecs are better suited for Web-based video


Legacy codecs (cont.)Legacy codecs (cont.)• Apple Video (CD-ROM)Apple Video (CD-ROM)

• Very fast codec but with low quality playbackVery fast codec but with low quality playback• Rapid compression makes it appropriate for testing editsRapid compression makes it appropriate for testing edits• Built into QuickTimeBuilt into QuickTime• Generally better suited for CD-ROM than for Web-based videoGenerally better suited for CD-ROM than for Web-based video• Plays well on lower-end machinesPlays well on lower-end machines


Legacy codecs (cont.)Legacy codecs (cont.)• Animation (Web/CD-ROM)Animation (Web/CD-ROM)

• Best suited for two-dimensional animation and computer generated Best suited for two-dimensional animation and computer generated (synthetic) video content(synthetic) video content

• Built into QuickTimeBuilt into QuickTime• As a lossless codec it doesn’t introduce any noise into the video As a lossless codec it doesn’t introduce any noise into the video

signalsignal• Produces large files when quality set to 100%Produces large files when quality set to 100%


Legacy codecs (cont.)Legacy codecs (cont.)• Graphics (Web/CD-ROM)Graphics (Web/CD-ROM)

• Similar in function to the Animation codec but only generates 8-bit Similar in function to the Animation codec but only generates 8-bit images (256 colors)images (256 colors)

• Generally produces files about 1/2 the size of the Animation codec Generally produces files about 1/2 the size of the Animation codec • Playback requires somewhat higher CPU requirements than Playback requires somewhat higher CPU requirements than

Animation codecAnimation codec• Built into QuickTimeBuilt into QuickTime


Modern codecsModern codecs• Sorenson Video (Web/CD-ROM)Sorenson Video (Web/CD-ROM)

• Built into QuickTimeBuilt into QuickTime• Enables variable bit rate (VBR) encodingEnables variable bit rate (VBR) encoding• Host of configurable features in the pro-versionHost of configurable features in the pro-version• Low data-rates make it superior for the WebLow data-rates make it superior for the Web• CD-ROM playback requires 100 Mhz + machineCD-ROM playback requires 100 Mhz + machine• Web playback requires Pentium or PowerMacWeb playback requires Pentium or PowerMac


Modern codecs (cont.)Modern codecs (cont.)• On2 VP3 (Web/CD-ROM)On2 VP3 (Web/CD-ROM)

• Recently developed open source codecRecently developed open source codec• Built into QuickTime and soon to be integrated into RealPlayerBuilt into QuickTime and soon to be integrated into RealPlayer• Enables clear 320x240 video that can be expanded to a full-screen Enables clear 320x240 video that can be expanded to a full-screen

640x480 resolution640x480 resolution• Low data-rates make it superior for both the Web and CD-ROMLow data-rates make it superior for both the Web and CD-ROM• Low CPU demands on the playback computerLow CPU demands on the playback computer• Outperforms the Sorenson codecOutperforms the Sorenson codec


Modern codecs (cont.)Modern codecs (cont.)• MPEG-2 (DVD-video)MPEG-2 (DVD-video)

• Standard for broadcast-quality digitally encoded videoStandard for broadcast-quality digitally encoded video• Primarily used for DVDsPrimarily used for DVDs• Excellent quality at high data rates (300 - 1000 KBps)Excellent quality at high data rates (300 - 1000 KBps)• Playback currently requires special hardwarePlayback currently requires special hardware• Not appropriate for use over networks connectionsNot appropriate for use over networks connections


Modern codecs (cont.)Modern codecs (cont.)• MPEG-4 (Web)MPEG-4 (Web)

• Currently under development for delivering interactive multimedia Currently under development for delivering interactive multimedia across networksacross networks

• Based on the QuickTime file format and optimized for delivery of Based on the QuickTime file format and optimized for delivery of video at Internet data ratesvideo at Internet data rates

• To be implemented in both MS NetShow and QuickTime 6To be implemented in both MS NetShow and QuickTime 6


Modern codecs (cont.)Modern codecs (cont.)• Real G2 (Web)Real G2 (Web)

• First modern video codec for the RealPlayer First modern video codec for the RealPlayer • Creates a good looking image on high-end machines while playing Creates a good looking image on high-end machines while playing

adequately on low-end systemsadequately on low-end systems• Can be used with or without special server softwareCan be used with or without special server software• Video can be viewed with a free client application or plug-inVideo can be viewed with a free client application or plug-in


Modern codecs (cont.)Modern codecs (cont.)• RealVideo 8 (Web)RealVideo 8 (Web)

• Part of the RealMedia architecture designed to support live and on-Part of the RealMedia architecture designed to support live and on-demand audio and video over the Webdemand audio and video over the Web

• Offers very good performance with lower data rates and motion Offers very good performance with lower data rates and motion intensive videointensive video

• Final version of RealMedia will support animations, MIDI, text, Final version of RealMedia will support animations, MIDI, text, images, vector graphics and presentationsimages, vector graphics and presentations


Modern codecs (cont.)Modern codecs (cont.)• RealVideo 9 (Web)RealVideo 9 (Web)

• Just released today for Wintel machinesJust released today for Wintel machines• Provides 30% improvement over RealVideo 8 and 50% over Provides 30% improvement over RealVideo 8 and 50% over

RealVideo G2RealVideo G2• Same quality at 1/2 the bit rate of MPEG-4Same quality at 1/2 the bit rate of MPEG-4• 1/2 screen playback at dialup rates (56Kbps), VHS quality at 1/2 screen playback at dialup rates (56Kbps), VHS quality at

broadband (160+ Kbps), and near DVD quality at LAN (500 Kbps) broadband (160+ Kbps), and near DVD quality at LAN (500 Kbps) ratesrates

Output OptionsOutput Options

Many options - Tape, Web, CD or DVDMany options - Tape, Web, CD or DVD• Dump-to-tape is good for classroom viewingDump-to-tape is good for classroom viewing

• Web, CD and DVD require compressionWeb, CD and DVD require compression

• Web-based streaming and progressive downloadWeb-based streaming and progressive download• Discreet’s Cleaner 5 (Mac/PC)Discreet’s Cleaner 5 (Mac/PC)• QuickTime Pro (Mac/PC)QuickTime Pro (Mac/PC)• Be sure and flatten Mac movies so they can play on a PCBe sure and flatten Mac movies so they can play on a PC

• Burning CDs (650 MB) Burning CDs (650 MB) • Roxio’s Toast (Mac/PC)Roxio’s Toast (Mac/PC)• Apple’s built-in Disc BurnerApple’s built-in Disc Burner

• DVD authoring (4.5 GB)DVD authoring (4.5 GB)• Apple’s iDVD or DVD Studio ProApple’s iDVD or DVD Studio Pro• Sonic Solutions DVDit (PC)Sonic Solutions DVDit (PC)

Resources on the WebResources on the Web

Codec CentralCodec Centralhttp://www.siggraph.org/education/materials/HyperGraph/video/codecs/Default.htm

2-Pop: The Digital Filmmaker's Resource Site2-Pop: The Digital Filmmaker's Resource Sitehttp://www.2-pop.com

Adobe Digital Video TutorialsAdobe Digital Video Tutorialshttp://www.adobe.com/motion/tips/main.html

Digital Video TutorialDigital Video Tutorialhttp://www.huntfor.com/photography/tutorials/digitvideo.htm

Creating Video on the MacintoshCreating Video on the Macintoshhttp://www.apple.com/creative/video/workflow/

iMovie Support PageiMovie Support Pagehttp://www.info.apple.com/usen/imovie/

Contact InformationContact Information

Jim DemmersJim Demmers404-894-8056404-894-8056

[email protected]@gtri.gatech.edu

working with digital video in the classroom jim demmers georgia tech research institute

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