COM 597 Streaming Media

1. COM 597Streaming Media Class 7 July 13, 2006

2. General Notes and Comments • Travis Petershagen, Seattle Podcasting Network • Pete Grondal, Mobile Devices, TBA

3. Profiles • Windows Media Encoder uses Profiles • What is a profile and how would I use one? • A profile determines how files or source groups are encoded • Each profile may include one or many target audiences, along with video and audio codec information • You can save the profile and use it repeatedly

4. Target Audiences • What is the concept of target audiences? • This is the naming convention for their multiple bitrate technology • With it you can select multiple target audiences (bit rates) and weave your different versions into one file

5. Moving Targets • An anomaly with the WindowsMedia version of MBR is the video is encoded with multiple qualities of compression. • But all the video files share only one Audio file • There are not multiple audio files only one so choose wisely • The lowest audience profile will determine your audio settings • All the video target audiences will share a video screen size

6. Which encoding mode to choose? • CBR? VBR? • My recommendation: • Start with VBR • Then two pass CBR • Then one pass CBR

7. Why VBR? • VBR when used on proper content • Long and varied in complexity • Will give you an appreciably better encoded clip given the same file size. • CBR is often using the bits in the wrong places and not having enough available in the difficult spots • The difference can be as high as 2-to-1 • Another way to look at it. If two files have the same quality, the VBR file will often be half the size of a CBR file • If your source is a file and you want to encode with CBR, then two pass is better than one pass

8. Using the frame buffer with CBR • Why use the default of 5 seconds? • If you are streaming a longer file (over say 10 minutes) increasing the buffer to 30 seconds will accomplish many of the same increase in quality that VBR does.

9. Windows .NET • If you are streaming over a server with Windows Media Services in Windows .NET Standard or Enterprise editions you can enable Fast Start • This allows the server to burst data to the players and filling the buffer in a shorter time than indicated, thus starting the file quicker

10. Microsoft Buzzword Translator • Fast Start: Instant on playback • Fast Cache: Download and cache the streaming content • Fast reconnect: Automatically reconnect to a stream if interrupted • Fast Recovery: Use forward error correction

11. Other Buzzwords Real’s version of the same stuff • TurboPlay It is their rapid playback and seeking technology Instant On is QuickTime’s version

12. More Buzzwords • URLs on Media Servers • Mount point – Real and QuickTIme • Publishing Point – Microsoft Windows Media V9 • Station – Windows Media prior to V9

13. A brief introduction to Mobile Media • 3G (3rd Generation) Mobile Networks • Capable of delivering vast quantities of data & multimedia • Target is handheld devices • Mobile networks are evolving from narrowband, circuit-switched networks • These were used primarily for voice and text

14. Brief cont. • New networks are broadband and utilize packet switching • Deliver broad range of internet-like media services • 3G is a real paradigm shift for the telecommunications industry • Once place to look is with the sales of camera phones v. digital still cameras

15. More mobile • Several 3G networks are up and running in Europe and Asia • Phones there can include: • Multiple cameras supporting real-time, person-to-person video calling • Video messaging • Playback of media content (news, sports, music videos, etc.)

16. A few technological challenges • No agreed to standards. Every company has a better mousetrap • It is the Wild West when it comes to competing technologies • As opposed to computing where you can assume either MS or Mac, with 3G it is a crap shoot what technology you will need to support, let alone screen size, color depth frame rate and screen direction (vertical or horizontal) • MPEG4 is the only video format supported by all phones

17. You can visit www.3Gpp.org to review what standards have been defined for Mobile

18. Hardware problems • Hardware variability also represents a significant challenge between mobile devices • Every few months a new crop of phones with new features • Not just screen display size and color quality changes

19. More Hardware problems • Operating systems • Processing power • Memory • Media format compatibility

20. Other technical challenges include: • Physical movement of a user from one network cell to another • Signal strength problems on the edge of a network • User’s proximity to a tower – will effect data flow • Number of devices operating simultaneously on the same cell • Physical speed that a device is traveling through the cell (e.g. car)

21. Blog Assignment for class 8 • Where and how is digital rights management failing. If you can, give a first person account where managing the portability, the delivery or re-use of digital media didn’t go the way you think it should.

22. Workshop • Creating and implementing profiles in Windows Media