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Chapter 19: Using Media and Streaming

Chapter 19: Using Media and Streaming. Understanding the Streaming Process. Streaming media are files that are sent in pieces by a service and played back by a client as the delivery continues. Streamed material can be live or on-demand.

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Chapter 19: Using Media and Streaming

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  1. Chapter 19: Using Mediaand Streaming

  2. Understanding the Streaming Process • Streaming media are files that are sent in pieces by a service and played back by a client as the delivery continues. Streamed material can be live or on-demand. • Live streaming is called progressive streaming or progressive download, while on-demand streaming is from material that is already stored to disk. In order to stream content successfully, the system requires that the network bandwidth be adequate to support the transfer of enough material to support user playback. For cloud computing where the media files are large and the connection is slow, this is a major consideration and potential bottleneck.

  3. When a live stream is sent multicast to 1,000 concurrent users at 500 kbps, the number of megabytes transferred is calculated like this: • MB transferred = Bandwidth x Time x Number of Users • MB transferred = 500 kbps x 3600 s x 1000/(8 x 1,024 x 1024)

  4. The amount of data transferred during streaming can be enormous. Assuming that you have a one-hour video file transferred at 300 kbps and encoded into a window that is 800X600 pixels in size, on-demand streaming would require the following:

  5. Size (MB) = Time (seconds) x bit rate (bps)/(mebibyte), where a mebibyte (MiB) is 8 x 1,024 x 1,024 bits • (3,600 x 300,000 bps)/ 8,388,608 = 128 MiB or about 135 MB/hour • Because 1 kbps is equal to 1,000 bps, in the line above 300 kbs is equal to 300,000 bps. Notice that this calculation uses mebibytes (MiB). A MiB is a measurement of the number of binary bytes in units of 2^20, which is what the prefix mebi- indicates. • A MiB is equal to 2^20 or 1,048,576 bytes.

  6. Protocol in use • A digital audio or video file is partitioned into many small pieces and played back at high speed.Depending upon the nature of the material, playing streamed material can suffer a certain amount of loss of transmitted packets, which is displayed as dropped frames or missing notes without the viewernoticing. This difference between streamed media and transferred media is fundamental in deciding which transfer protocol to use. For transferred media, the entire file must be transmitted with fidelity,thus TCP (Transmission Control Protocol) is the transmission protocol. In a streamed media scenario, fidelity isn't a prerequisite, thus UDP (User Datagram Protocol) is the transmission protocol.

  7. Cloud computing advantages • • Access to large scale storage, which enable the storage of large media files and on-demand media libraries. • Amazon S3, Microsoft Windows Azure Blob Storage, Nirvanix, EMC Atmos Online, Mezo,Google Storage for Developers. Rackspace CloudFiles, and Eucalyptus are examples of some of the large cloud storage systems available to content providers. Some of these systems, such as Microsoft Azure and Google Storage, support the applications developers' position on those SaaS services. • • Access to scalable compute engines and network storage that can serve as the streaming server to large audiences. • • Access to a scalable compute engines that can be useful when you want to performencoding/decoding or transcoding on media files.The company Encoding.com is an example of a transcoding service where you can use an Adobe AIR application to drag and drop files that are encoded right to your desktop. • Access to content delivery networks or edge systems that can push content out to users based on geographical location.

  8. Audio streaming • Audio streaming makes much lower demands on network bandwidth than video streaming does. • An audio file is roughly 500 times smaller than a correspondingly long video file. Therefore, the first streaming services that appeared even before broadband became widely available were audio streaming services. • An early entrant into this area was Real Networks' Real Player technology and its associated protocol suite. There was a time when many content providers required you to use RealAudio technology and the RealPlayer media player. • Two other competing formats appeared that have gotten general acceptance: Windows Media Player and Apple QuickTime. These players play video formats as well as audio formats, and all are available as stand-alone players or as browser plug-ins.

  9. Working with VOIP applications • Voice over IP or VoIP is a set of communication protocols for delivering voice over the Internet. Some of these services have been migrated to the cloud, particularly those services that require the involvement of large number of servers. VoIP uses additional protocols and standards other than audio streaming; these are the most commonly used VoIP standards: • H.323 H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) that defines the protocols to provide audio-visual communication sessions on any packet network. • IP Multimedia Subsystem (IMS)• Media Gateway Control Protocol (MGCP)• Session Initiation Protocol (SIP)• Real-time Transport Protocol (RTP)• Session Description Protocol (SDP) • Skype • Google voice and Google talk

  10. Video Streaming • Video streaming over the Internet has become one of the major broadcast transmission media in a rathershort time. Many trends have come together to help make this transition a reality, including broadbandnetworks, high-capacity commodity disk drives, low-cost computing power, and now cloud computing.Video streaming is one of these technologies that benefits greatly from deployment in the cloud.

  11. Television in cloud • Television is a very important industry. The average American watches five hours of TV a day, and $70 billion a year is spent on advertising. The number of TV watchers dwarfs the 1 billion PC users, andeven the 2 billion cell phone users. Worldwide, there are 4 billion TV watchers.

  12. Streaming video formats • • Firefox 4 (WebM)• Chrome (h.264 supported now, WebM enabled version available via Early Release Channel)• Opera 10.6+ (WebM)• Apple Safari (h.264, version 4+)• Microsoft Internet Explorer 9 (h.264, Platform Preview 3)• Microsoft Internet Explorer 6, 7, or 8 with Google Chrome Frame installedYou should expect HTML5 to be standard in the official release versions of these browsers before 2010ends.

  13. You also can view HTML 5 content in the following media players:• Media Player Classic (http://mpc-hc.sourceforge net/)• Moovida Core (http://www moovida.com/)• VLC (http://www.videolan.org/)• Winamp (http://www.winamp.com/media-player/)• XBMC (http://xbmc.org/)Video formats are only half of the story when it comes to video file formats. The second half of the story is the format for the streaming protocol that encodes the video file. Several of these container formats are in use.The most widely used streaming video file container format is H.264/MPEG-4 Part 10. MPEG-4 Part 10 is also known as MPEG-4 AVC, which stands for Advanced Video Coding.

  14. Youtube

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