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COM 597 Streaming Media. Class 7 July 13, 2006. General Notes and Comments. Travis Petershagen, Seattle Podcasting Network Pete Grondal, Mobile Devices, TBA. Profiles. Windows Media Encoder uses Profiles What is a profile and how would I use one? - PowerPoint PPT Presentation
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COM 597Streaming Media
Class 7July 13, 2006
General Notes and Comments
• Travis Petershagen, Seattle Podcasting Network
• Pete Grondal, Mobile Devices, TBA
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
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
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
Which encoding mode to choose?
• CBR? VBR?
• My recommendation:
• Start with VBR
• Then two pass CBR
• Then one pass CBR
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
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.
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
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
Other Buzzwords
Real’s version of the same stuff
• TurboPlay It is their rapid playback and seeking technology
Instant On is QuickTime’s version
More Buzzwords
• URLs on Media Servers
• Mount point – Real and QuickTIme
• Publishing Point – Microsoft Windows Media V9
• Station – Windows Media prior to V9
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
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
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.)
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
You can visit www.3Gpp.org to review what standards have been defined for Mobile
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
More Hardware problems
• Operating systems
• Processing power
• Memory
• Media format compatibility
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)
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.
Workshop
• Creating and implementing profiles in Windows Media