2. 08/03/02000 David Bown MSc CBLT/Multimedia 1 Video and DVD

3. 08/03/02000 David Bown MSc CBLT/Multimedia 2 What is DVD? DVD was the first distribution medium designed for digital video. Hence it originally stood for Digital Video Disc. Digital offers dramatic improvements in transmission efficiency compared to analogue video.

4. 08/03/02000 David Bown MSc CBLT/Multimedia 3 Studio Quality Images DVD now stands for Digital Versatile Disc. It offers an optical (and audio) storage medium with enormous capacity and bandwidth compared to CD-ROM. Standard specifications include MPEG-2 video which gives studio quality 740X480 pixel images (VHS tape: 320X240).

5. 08/03/02000 David Bown MSc CBLT/Multimedia 4 Recordable DVD DVD-R Recordable once, read on DVD-ROM. DVD-RAM read and write to 2.6 GB DVD- RAM Disc and read and write once to 3.9 GB DVD-R Discs. DVD-Ram discs readable on DVD-R and DVD-ROM drives.

6. 08/03/02000 David Bown MSc CBLT/Multimedia 5 High Capacity Full length films 133 minutes of MPEG-2. Single layer discs: 4.7 Gbyte. Dual-layer discs: 8.5 Gbyte.

7. 08/03/02000 David Bown MSc CBLT/Multimedia 6 Double-sided DVDs Double-sided dual layer discs with back to back bonding. By combining with Dual layer a massive capacity of 17 Gbytes can be obtained.

8. 08/03/02000 David Bown MSc CBLT/Multimedia 7 Data Storage on DVD Like CD-ROMs data is recorded in spiral of tiny pits.

9. 08/03/02000 David Bown MSc CBLT/Multimedia 8 Capacity Gains over CD-ROM DVDs obtain significantly more capacity by: Shorter wavelength laser; Smaller pits (0.4 micrometers v 1.1 on CD- ROMS) Denser track pitch (0.74 micrometers v 1.6 on CD-ROMS) Increased efficiency in channel encoding.

10. 08/03/02000 David Bown MSc CBLT/Multimedia 9 Construction of DVD

11. 08/03/02000 David Bown MSc CBLT/Multimedia 10 Variable Bit Rate Average bit rate for DVD is 4.7 mbs. But the rate varies between >3 to 10.07mbs. This enables high quality images to be generated from complex scenes.

12. 08/03/02000 David Bown MSc CBLT/Multimedia 11 MPEGs (Moving Pictures Expert Group) Video standard for DVD, MPEG uses three types of video frame: I-Frames contains all spatial info of video frame. These are used as the “hooks”, every scene change requires a new I-Frame. B-Frames (Highest compression). P-Frames.

13. 08/03/02000 David Bown MSc CBLT/Multimedia 12 MPEG Advantages Universal compatibility: Universal compatibility: MPEG files are system independent. Greater compression ratios Greater compression ratios than any other format (up to 200:1). Highest quality Highest quality compression does not lead to sacrifice in quality. MPEG delivers broadcast quality video.

14. 08/03/02000 David Bown MSc CBLT/Multimedia 13 Advantages of DVD Added features over Video tape. Immediate scene access. There are more than 5,600 movie and music videos currently available. Same size as CD but can store an entire film. DVD offers superior picture and sound.

15. 08/03/02000 David Bown MSc CBLT/Multimedia 14 Future of DVD? DVD or Sony’s Phase-Change Rewritables (PCR) disc or NEC (Betamax v VHS). Hitachi propose a DVD-RAM disc with phase-change technology that will be retrospective to CD-ROM and DVD-ROM. Blue lasers developed in Japan mean a laser footprint even smaller than DVD can be obtained.

16. 08/03/02000 David Bown MSc CBLT/Multimedia 15 History of Video on the Web Multimedia became commonplace back in 1992 with CD-ROMS. But the Web has low bandwidth and cannot cope easily with moving pictures. TV uses “fat” cable infrastructure, Web uses “thin” telephone infrastructure. Moving images on the Web like “sucking a bowling ball through a garden hose”.

17. 08/03/02000 David Bown MSc CBLT/Multimedia 16 Video Compression Temporal compression: frame by frame. Spatial compression: deletes information common to entire file and defines ‘areas’ rather than pixels. In addition, file size can be reduced by cutting: Colours frame rate audio quality.

18. 08/03/02000 David Bown MSc CBLT/Multimedia 17 Hardware v Software Codecs Hardware codecs are faster and require fewer CPU resources. Delivers high-quality results. But are more expensive. Software codecs are less expensive, e.g. freeware versions. Take long time to analyse and compress.

19. 08/03/02000 David Bown MSc CBLT/Multimedia 18 DV Filmmaking Digital Video (DV) was introduced to U.S. consumers in 1994. Digital Video is a high resolution video format that stores, manipulates and relays data like any other computer data.

20. 08/03/02000 David Bown MSc CBLT/Multimedia 19 Benefits of DV Excellent images, being digital the copy quality is identical to the original. Three separate signals for each colour offering good colour reproduction. Ability to use “Firewires” high speed connections in and out of computers. Portable and relatively inexpensive cameras.

21. 08/03/02000 David Bown MSc CBLT/Multimedia 20 ‘FireWire’ - Wired for Speed A high-speed serial bus cable designed by Apple to provide cheap digital interface. Based on the port found on Nintendo Gameboy. Provides a transfer rate of 50 megabytes/sec (Broadcast quality needs just 3.6) It can link up to 63 devices. Unlike SCSI no device IDs need to be set.

22. 08/03/02000 David Bown MSc CBLT/Multimedia 21 Webmonkey Hints Use a tripod. Use tight close-ups. Use quality resources. Do not shoot very dark or light backgrounds. Capture rate no bigger than 320 x 240 pixels at 10 frames per second.

23. 08/03/02000 David Bown MSc CBLT/Multimedia 22 The End