Com 597 Streaming Media Class 6 July 11, 2006

Packetization To stream a file over the internet you need to break the file down Kilobyte sized chunks These are called packets The audio and video needs to synch up and must be sent fast enough, but not too fast Packets that are lost in transit need to be detected and resent

Packetization cont. The process of breaking the streaming file into chunks is called packetization

Could I have a hint? To speed up the process and reduce the work of servers this is often done ahead of time This is called hinting Hinting adds additional information in the file (a hint track) to tell the media server how to packetize the stream. The hint track not only has data defining what audio and video exist in the file, but also how large a chunk to send over the internet and at what time intervals.

Common Internet File Formats Category One Video container file formats, hierarchical in structure and hold many different kinds of media (Audio, video and text.) This data is synchronized in time.

Common Internet File Formats Category Two Simple raw storage of stream formats This holds the compressed video data without headers or footers They are essentially a live audio-video stream saved to disk

Common Internet File Formats Category Three Play list, index and scripting formats These don’t hold the actual media files These are pointers and commands that indicate where the files are located These files are usually, comparatively small.

Microsoft and Windows Media The standardization of Windows Media technologies by international standards groups generally means the format will not suddenly change. Inertia = stability MS has seen the benefits of non-discriminatory licensing terms with companies Low cost = wide distribution

Windows Media Technology Like Real, there is a family of codecs Video- Windows Media Video 8, Windows Media Video 7, Microsoft MPEG-4 V3 & MPEG-4 V1 Audio- Windows Media Audio V7 & ACELP.net voice codec

Windows Media also supports: Video- VP3, ClearVideo, VDOnet, Vivo video Audio- Voxware MetaSound and MetaVoice, Learnout and Hauspie, MP3, Vivo audio, and all pre-G2 Real Audio and Video codecs Why the Real support? Windows Media started as NetShow, which licensed RealNetworks technology

Microsoft Files AVI (Audio Video Interleaved) Developed in 1992 First real-time playback of video on a PC These can hold most anything. It works on every platform It is not all that great at managing sync It can be quite slow This is because the file index is often located at the end of the file The format has been extended so much that variations wont always play in every player

Microsoft Files ASF (Advanced Streaming Format) This is Microsoft’s proprietary format MS Filed a patent for it in 1998 Released in 2002 One of the dominant formats Fixed a lot of the problems inherent in AVI files It can show up as WMV or WMA Primarily designed to hold synchronized Audio and video

Microsoft Files ASX (Active Streaming Index) Index files that work in the Windows Media system They are metadata pointers The direct a player where to retrieve the actual media files Can be one URL or a long list (playlist) They can be nested

Why choose Windows Media? Consider your audience: Weather you like the Company or not is irrelevant. If you target audience is in the business world then you need to seriously consider Windows media Because WM comes bundled with the Microsoft OS, and because nearly every enterprise corporation runs on a Windows environment, a staggering percentage of the Fortune 1000 businesses will have Windows Media on their employee’s computers. Microsoft is the clear leader in market share in the enterprise space Plus, their server technology incorporates many aspects of DRM quite seamlessly.

File Metrics Measuring Streaming media quality is becoming widely acknowledged as supremely important Three companies currently are the market leaders in measuring the quality of streaming media delivery One of them is Keynote is the global leader in web performance measurement They acquired Streamcheck in 2003 This is an automated service that measures both quality of streams and reliability

How they do it: They measure audio and video streams from multiple locations throughout North America, Japan and Europe They use measurement computers, called “Agents” And Agent will try and connect with your stream about 10 times an hour Once connected they play your stream for about 60 seconds The Agent computers will record: Network Statistics like packet statistics Connection statistics like connection success, bit rate, buffer and re-buffer Server statistics like server type streaming protocol Presentations statistics like frame rate, player errors, metafiles, URLs

Workshop Demo Let me walk you through before your begin

Customizing Your Settings In the compression tap, check the bit rate selections appropriate to your target audience Audio format: you can adjust the amount of bandwidth used by the audio track in your video. If you assign a lower audio rate then you are allocating more bits for the video. An example would be a sporting event file. High fidelity audio is not as important as smooth video. A music video may want more bits for audio because fidelity is more important in this scenario.

Customizing Your Settings In the compression tap, check the bit rate selections appropriate to your target audience Audio format: you can adjust the amount of bandwidth used by the audio track in your video. If you assign a lower audio rate then you are allocating more bits for the video. An example would be a sporting event file. High fidelity audio is not as important as smooth video. A music video may want more bits for audio because fidelity is more important in this scenario.