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Internet Applications Development

Internet Applications Development. Electronic Publications in the Age of Streaming Audio and Video: How to Do It. Renato M.E. Sabbatini, PhD. Editor-in-Chief Intermedic Journal Informática Médica Center for Biomedical Informatics State University of Campinas, Brazil. Adding Audio and Video.

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Internet Applications Development

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  1. Internet Applications Development Electronic Publications in the Age of Streaming Audio and Video: How to Do It

  2. Renato M.E. Sabbatini, PhD Editor-in-Chief Intermedic Journal Informática Médica Center for Biomedical InformaticsState University of Campinas, Brazil

  3. Adding Audio and Video • Can I add audio and video to my Web site or Web-based publication? • How can I achieve optimal combinations of speed and quality? • Which tools are best for creating specific types of multimedia experience? • How audio and video can be presented and served?

  4. Modalities of Audio and Video on the Internet 1. Binary file downloading and local playback • The whole file must be downloaded before playback can start • File occupies disk space in client • Live transmission is not possible • Interactivity is not possible • Impractical except for very small files

  5. Audio Player Plug-Ins

  6. Plug-Ins for Videos Apple QuickTime Windows Media Player

  7. Modalities of Audio and Video on the Internet 2. Streaming audio and video • A continuous flow of digital packets is sent to the client and played as they arrive • Speed is independent of file size • There is no need to store the file in the client • Real time transmission is possible • Interaction is possible

  8. Streaming Media Client Server Sends audio or video files in a continuous stream of small packets Continuous playback of audio and video packets

  9. RealMedia Plug-In Presentation • Video alone or synchronized video and audio

  10. RealMedia Plug-In Presentation • Audio file alone

  11. Streaming Audio and Video • Vivo and RealSystems were the first companies to deliver real-time streaming audio and video over the World Wide Web. • Streams are compressed and encoded from either a preexisting sound file or live audio, using a protocol called codec. • The codecs can output files that are optimized for 14.4 to 56 Kbps modem delivery, or delivery over a higher speed line such as LAN, ISDN or T1.

  12. Sound/Video Acquisition and A/D Conversion How RealMedia Works RealMedia Encoder RealMedia Server RealMedia Player

  13. How RealMedia Works • A RealAudio Server connection is a two-channel, two-way communication system: • The UDP protocol is used for sound-data transmission • The TCP protocol is used to interchange bandwidth and codec data as to communicate pause, fast forward, play, and rewind commands.

  14. RealAudio Features • RealAudio is an open architecture application • The Playback Engine Application Programming Interface (API) provides software developers with direct access to the functionality of the RealAudio Player • It is continually evolving. Latest technology (G2) delivers high quality audio and video with interactive features • Very easy to create and deploy content.

  15. The RealAudio Player • Two versions: a stand-alone program that can also be used as a browser helper application, and a browser plug-in. • The stand-alone application is a fully functional program that you can use to play RealAudio files from any source, including a hard drive, a corporate intranet, or the Web. • Works with any sound and video boards • Free downloading of standard version, there is also a commercial professional version.

  16. Sound Quality and Compression: Example 0ne-minute monaural sound file sampled at 22 kHz • WAV file is 2.6 megabytes; RealAudio, encoded for 6.5Kbps is 42 kilobytes, for ISDN is 296 kilobytes. Compression ratios of 62:1 and 8:1, respectively. • The low-bandwidth file has AM radio quality and is best for speech only, whereas the quality of the high-bandwith approaches CD-ROM quality, adequate for stereo music • A loss correction system minimizes the impact of lost packets. Works well with 2-5 % loss, but works with up to 8% loss.

  17. Digital Editing and Preparation Conversion to Streamed Format Uploading to Server Development Steps Digital Recording of Audio/Video

  18. Digital Editing and Preparation Conversion to Streamed Format Uploading to Server Development Steps WAVAVI Digital Recording of Audio/Video RA

  19. Critical Selection Parameters • Audio codec and bit rate • Video codec and bit rate • Frame rate • Frame size

  20. Some Technical Tips • If you're serving an audience that has a variety of connection speeds, encode the content with several different codecs, one for each speed. • You should budget 3M of RAM plus 60K for each simultaneous user.

  21. Selection of Video Rate • Fixed camera shot with low motion--The frame rate will run between 4 and 10 • Fixed camera shot with some motion--The frame rate may drop toward 2 fps. • Fixed camera shot with high motion--The frame rate drops to about 1 fps. • Zooming camera with low motion--Expect a frame rate of about 2 fps. • Multiple shots, low motion--The frame rate approaches 1 fps. • Multiple shots, high motion--The frame rate drops below 1 fps.

  22. Software for Editing Digital Audio and Video • Adobe Premiere • Creative Multimedia Suite

  23. Choosing the Best Format

  24. Audio Formats

  25. Choosing Video Bit Rates

  26. Inserting Multimedia into the Web page • Call to the external helper applicationA separate window opens up, with all RealPlayer controls, which can be customized by the user • Embedded plug-in calls, with several options for display and playback control, set up by the developer • There is a wizard for selecting the desired combination and generating HTML code

  27. Referencing the File • A RealAudio URL has the format:pnm://server:port#/pathname • pnm:// indicates the file is located on a RealAudio Server system. • Server:Port# is the address of the RealAudio Server. • pathname is the complete directory path and file name. • Example: pnm://audio.realaudio.com/welcome.ra • This pointer is placed into na ASCII file with the extension .ramor .rpm(metafile)

  28. Referencing the File • HREF:<A HREF="pnm://www.epub.org/dream.ram">Patient case</A> • EMBED:<EMBED SRC=" pnm://www.epub.org.br/dream.rpm" WIDTH=300 HEIGHT=134> • RealPlayer Controls and Options:CONTROLS, AUTOSTART, CONSOLE, and NOLABELS

  29. Synchronized Multimedia • Synchronized HTML pages with streaming audio (guided tours, slide shows)

  30. Synchronized Multimedia • Packing audio and PowerPoint slides into a RealMedia file (synchronized audio with slides control: great for slide shows

  31. How RealPresenter Works • Create slide presentation using Microsoft PowerPoint • Using mike and PC´s sound board, narrate the slide show, pressing the ´next slide´ key as you go • PowerPoint will create a set of linked WAV files, one for each slide, with timing • Click on Tools/Create RealMedia and follow the wizard to create .RA file • Create .RAM metafile, upload to server

  32. Other Streaming Solutions • Netscape´s Media Player (LiveAudio) • MPEG 3ISO CD 11172 Moving Pictures Experts Group • XING´s StreamWorksMPEG-based, encoder (WAV, QT, AVI), player • VXTreme, VDONet • Apple QuickTime

  33. The Microsoft Approach • Aims to establish its Active Streaming Format (ASF) as the de facto standard for streaming video. • Has demonstrated a unified multimedia technology called DirectX. • Has developed a streaming video product, NetShow, to challenge RealVideo for market dominance. • NetShow comes with tools that convert existing video files, including AVI and QuickTime movies, to streaming files

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