Working with Digital Video in the Classroom

1
Working with Digital Video in the Classroom

• Jim Demmers
• Georgia Tech Research Institute

2
Digital Video

• So what is digital video?
• It can be a variety of things
• A movie on DVD
• A home video stored on tape
• A QuickTime movie trailer on the Web
• Digital video is stored as a series of ones and
  zeros
• How is it different from analog video?
• Capture digital video - digitize analog video
• Capturing is akin to copying a computer file -
  each generation is virtually identical to the
  parent
• Digitizing samples a fluctuating voltage signal
  at discreet intervals, which adds generation loss
• As long as the video stays digital it doesnt
  lose any integrity

3
Video Capture

• Some things you need to know
• Types of video signals
• Composite, S-Video, Component YUV and RGB,
  FireWire
• Start with the best video source available
• VHS - 8mm - Hi-8/S-VHS - Beta SP/MII - DV/DVCPRO
• Avoid generation loss
• Keep your frames clean
• Be aware of Gamma differences
• Purchase a fast A/V hard drive
• Keep your capture drive defragmented

4
Video Capture

• Hard disk storage for video
• Ultra ATA vs Ultra2 SCSI drives
• ATA is fast and cheap now
• Drive specifications
• sustained transfer speed at least 8 MB/sec
• seek time less than 9 ms
• spindle speed at least 5400 rpm
• How much space do you need for Digital video?
• Data transfer rate for DV-format video is 3.6
  MB/sec
• 3.6MB/sec 60 sec 216 MB/min 13 GB/hour
• Multiply by 5 (for project, render test files)
  1 GB/min

5
Video Capture

• Digitizing analog video requires an A/D converter
  or capture card
• Good choices in A/D converters are
• Sony DVMC-DA2
• Dazzle Multimedias DV-Bridge
• Formac Studio
• Power R Directors Cut
• Good choices in capture cards for the PC are
• Pinnacle Studio DV
• Canopus DV Raptor

6
Post Production

• Linear vs non-linear editing
• Linear editing copies shots from one video
  storage media to another in sequence
• Non-linear editing uses a computer hard drive as
  random-access storage media
• Most non-linear editors are also non-destructive
• you can change or delete captured clips without
  affecting the original source clip
• Non-linear editing Tools
• Premiere (Mac/PC), Final Cut Pro, iMovie (Mac)

7
Post Production

• So whats it take to put together a good DV
  capture and editing system?
• A computer with a fast processor and lots of RAM
• 60 to 90 GB of fast hard disc storage
• A video capture card or native firewire
• A non-linear editing program
• Recording equipment (VTR/DVCR, CD-R or DVD drive)
• And all of this for under 2500

8
Video Compression

• Why compression?
• bandwidth and playback limitations
• Video compression/decompression requires a codec
• software/hardware technology that reduces the
  amount of information within individual video
  frames
• Factors that effect video compression
• bit depth - number of colors displayed
• frame size - number of pixels used to store each
  frame
• frame rate - number of video frames
  captured/played per second

9
Video Compression

• 3 primary criteria to consider when selecting a
  codec
• Compression level
• Quality of compressed video
• Compression/Decompression speed
• Its during the decompression process that codecs
  display their strengths and weaknesses
• Video compression tools
• Cleaner 5
• QuickTime

10
Video Compression

• Legacy codecs
• Cinepack (Web/CD-ROM)
• Photo JPEG (Web)
• Apple Video (CD-ROM)
• Animation (Web/CD-ROM)
• Graphics (Web/CD-ROM)
• Modern codecs
• Sorenson Video (Web/CD-ROM)
• On2 VP3 (Web/CD-ROM)
• MPEG-2 (DVD-video)
• MPEG-4 (Web)
• Real G2/RealVideo 8/9 (Web)

11
Video Compression

• Legacy codecs
• Cinepack (Web/CD-ROM)
• Good for medium quality CD-ROM video
• Extremely low CPU requirements - works well on
  older computers
• Built into MS Video for Windows and QuickTime
• Lower quality than many other codecs at the same
  data rates
• Doesnt produce good results at Web data rates
  (below 30KBps)
• Photo JPEG (Web)
• Used for still images editing and storage of
  high-quality video files
• Built into MS Video for Windows and QuickTime
• Good choice for low-data rate slide show movies
• Not well suited for CD-ROM or higher data rates
• Other codecs are better suited for Web-based
  video

12
Video Compression

• Legacy codecs (cont.)
• Apple Video (CD-ROM)
• Very fast codec but with low quality playback
• Rapid compression makes it appropriate for
  testing edits
• Built into QuickTime
• Generally better suited for CD-ROM than for
  Web-based video
• Plays well on lower-end machines

13
Video Compression

• Legacy codecs (cont.)
• Animation (Web/CD-ROM)
• Best suited for two-dimensional animation and
  computer generated (synthetic) video content
• Built into QuickTime
• As a lossless codec it doesnt introduce any
  noise into the video signal
• Produces large files when quality set to 100

14
Video Compression

• Legacy codecs (cont.)
• Graphics (Web/CD-ROM)
• Similar in function to the Animation codec but
  only generates 8-bit images (256 colors)
• Generally produces files about 1/2 the size of
  the Animation codec
• Playback requires somewhat higher CPU
  requirements than Animation codec
• Built into QuickTime

15
Video Compression

• Modern codecs
• Sorenson Video (Web/CD-ROM)
• Built into QuickTime
• Enables variable bit rate (VBR) encoding
• Host of configurable features in the pro-version
• Low data-rates make it superior for the Web
• CD-ROM playback requires 100 Mhz machine
• Web playback requires Pentium or PowerMac

16
Video Compression

• Modern codecs (cont.)
• On2 VP3 (Web/CD-ROM)
• Recently developed open source codec
• Built into QuickTime and soon to be integrated
  into RealPlayer
• Enables clear 320x240 video that can be expanded
  to a full-screen 640x480 resolution
• Low data-rates make it superior for both the Web
  and CD-ROM
• Low CPU demands on the playback computer
• Outperforms the Sorenson codec

17
Video Compression

• Modern codecs (cont.)
• MPEG-2 (DVD-video)
• Standard for broadcast-quality digitally encoded
  video
• Primarily used for DVDs
• Excellent quality at high data rates (300 - 1000
  KBps)
• Playback currently requires special hardware
• Not appropriate for use over networks connections

18
Video Compression

• Modern codecs (cont.)
• MPEG-4 (Web)
• Currently under development for delivering
  interactive multimedia across networks
• Based on the QuickTime file format and optimized
  for delivery of video at Internet data rates
• To be implemented in both MS NetShow and
  QuickTime 6

19
Video Compression

• Modern codecs (cont.)
• Real G2 (Web)
• First modern video codec for the RealPlayer
• Creates a good looking image on high-end machines
  while playing adequately on low-end systems
• Can be used with or without special server
  software
• Video can be viewed with a free client
  application or plug-in

20
Video Compression

• Modern codecs (cont.)
• RealVideo 8 (Web)
• Part of the RealMedia architecture designed to
  support live and on-demand audio and video over
  the Web
• Offers very good performance with lower data
  rates and motion intensive video
• Final version of RealMedia will support
  animations, MIDI, text, images, vector graphics
  and presentations

21
Video Compression

• Modern codecs (cont.)
• RealVideo 9 (Web)
• Just released today for Wintel machines
• Provides 30 improvement over RealVideo 8 and 50
  over RealVideo G2
• Same quality at 1/2 the bit rate of MPEG-4
• 1/2 screen playback at dialup rates (56Kbps), VHS
  quality at broadband (160 Kbps), and near DVD
  quality at LAN (500 Kbps) rates

22
Output Options

• Many options - Tape, Web, CD or DVD
• Dump-to-tape is good for classroom viewing
• Web, CD and DVD require compression
• Web-based streaming and progressive download
• Discreets Cleaner 5 (Mac/PC)
• QuickTime Pro (Mac/PC)
• Be sure and flatten Mac movies so they can play
  on a PC
• Burning CDs (650 MB)
• Roxios Toast (Mac/PC)
• Apples built-in Disc Burner
• DVD authoring (4.5 GB)
• Apples iDVD or DVD Studio Pro
• Sonic Solutions DVDit (PC)

23
Resources on the Web

• Codec Central
• http//www.siggraph.org/education/materials/Hyper
  Graph/video/codecs/Default.htm
• 2-Pop The Digital Filmmaker's Resource Site
• http//www.2-pop.com
• Adobe Digital Video Tutorials
• http//www.adobe.com/motion/tips/main.html
• Digital Video Tutorial
• http//www.huntfor.com/photography/tutorials/digi
  tvideo.htm
• Creating Video on the Macintosh
• http//www.apple.com/creative/video/workflow/
• iMovie Support Page
• http//www.info.apple.com/usen/imovie/

24
Contact Information

• Jim Demmers
• 404-894-8056
• jim.demmers_at_gtri.gatech.edu