COM 597 Streaming Media Class 5 July 19, 2007. Multicast v. Unicasting Streaming media may be...

COM 597Streaming Media

Class 5July 19, 2007

Multicast v. UnicastingStreaming media may be delivered in three ways

• Unicast: A server delivers a stream to each individual user. On-demand is always Unicast.

• Broadcast: A single stream is delivered to many users simultaneously, with each user having his/her own connection to the server

• Multicast: A single stream is broadcast on a network using a special multicast IP address. When viewers join, their players are instructed to grab packets of the broadcast on the network. Multicast is only used for live and simulated live delivery

What is "Simulated Live"?

• A stream of prerecorded content presented as if it is live.

• http://www.wolfgangsvault.com/

• Most webcasts are delivered via unicast delivery. One user --- One stream

• In a broadcast situation you have a large number of people all watching the same stream. Using traditional Unicast model, each user is sent an individual and unique stream. That puts a big load on the network and the servers. Multicast allows multiple users to tap into one stream.

• Multicast is more efficient because only one stream is

sent out across a multicast-enabled network.

Here is how it works

To get the media a media player simply tunes into a particular IP address that has the stream. The local router sends each media player a copy of the stream. The nice part is the stream only has to traverse the distance from the router to the server, not around the world or across the country.

Here is how it works

• Multicast routers can send copies of the stream to other multicast routers, which can then multicast the stream on a local network

• Multicast will only work if both the server and client are multicast enabled.

• All three of the major platforms support multicasting

Multicast pitfalls• One of the pitfalls of multicasting on the internet is all the

routers on the path must be multicast enabled. That is why you might need to rely on a CDN

• This is principally because many of the folks controlling different networks don’t want stray multicast content on their networks.

• Both Real and WindowsMedia support protocol rollover, where viewers who can’t get the multicast are connected to the stream via unicast.

http://www.ipmulticast.com/

Other Protocols to be aware ofWeb Acronym Name Use

UDP User Datagram Protocol Sending data in a continuous stream

RTP Realtime Transport Protocol when streaming media servers build packets of data and send them to the media player, the RTP instructs the server how to reconstruct these packets. This is used specifically with RTSP

RTCP Real Time Control Protocol RTCP packets work with RTP packets to check delivery. It is a way to check service quality

MMS Microsoft Media Services A proprietary streaming protocol, just like RTSP. Both Real and MS support MMS. Most Windows Media Metafiles have MMS as the irst three letters of the streaming URL

1-2-3 Smile!

• SMIL stands for Synchronized Multimedia Integration Language

• W3C developed it for Multimedia on the Internet (Now SMIL 2.1)

• It is used for displaying concurrent data – interactivity, layout, timing

How does SMIL work?

• An author can specify multiple data types and different regions in the UI

• Streams can be combined, re-used, and moved around in time and space

• This gives a developer both freedom and flexibility

Lets say you were creating a sports show

• At the bottom you can stream a text stream of recent scores. It will render as high quality graphics

• Thumbnails of additional information

• Logo of your show in the corner

• Streaming media

What is SMIL

• SMIL is simple XML-based mark-up language

• SMIL files are simple text looking an awful lot like HTML

• SMIL can be played back on a variety of players, but are not universal

SMIL Coding Concepts

• When creating SMIL presentations you need to think about your layout in layers

• Not just for design but also for coding• SMIL works not just in X & Y axis, but also on

the Z axis (index) This is how you manage layer order

SMIL Coding Concepts

• A SMIL document is similar in structure to an HTML document

• Like HTML there is a <head> section and a <body> section

• The <head> section contains layout and metadata information.

• The <body> section contains the timing information

Stream Synchronizing in SMIL

• Clips can be grouped so that they play back in parallel or in sequence.

• These groups can be nested (groups within groups)

• When you use timing attributes you can specify timing relative to the presentation timeline or the clip's internal timeline

Where are you likely to see it?

• SMIL is being implemented on handheld and mobile devices

• Multimedia Messaging Service (sometimes referred to as Mini-Me SMS) is a video and picture equivalent of SMS also predominantly used in mobile media.

More SMIL Info

• Beginning Chapter 26- 32 in Streaming Media Bible (pp587-697)

RealNetworkshttp://www.realnetworks.com/resources/howto/smil/smilbasics.html

WC3http://www.w3.org/AudioVideo/

Streaming Media Worldhttp://smw.internet.com/smil/smilhome.html

Streaming Bitrate VariationsWeb Acronym Name Use

VBR Variable Bit Rate The encoded rate it is a bit more fluid. Especially with content changes in quality e.g. low-motion talking head v. high motion footage. This is most often used in a non-streaming scenario.

CBR Constant Bit Rate Rate is constant through the file

MBR Multiple Bit Rate The player and server shift among two or more constant bit rates, depending on throughput

Fortune 1000 Companies expectations on Streaming Budgets 2004

• The debate of late is less about platforms and more about how do you make money?

• Business models is the current focus• Better mouse trap?

Issues at hand

• How large does your media library need to be?• What are the licensing issues?• What is Fair Use?• “Inventory leakage” vs.

“Content monetization”• How does this technology enhance the brand?

Generate revenue? Connect with customers? Increase sales? What is the ROI?

• Channel Control

Digital Darwinism

• 1st digital content delivery network in 1996• Sandpiper Networks 1997• FastForward Networks 1997• These were absorbed by other networks• Other once promising companies:

– Razorfish– Scient– Viant– Zephyr

Four Keys to a Profitable Digital Media Business

• Scalability• Security• Intelligence• Quality

• The choices you make around these four issues will make or break your business

Scalability

• Marketshare does not equal profitablity

• Free v. ad revenue supported content– MTV example– Live webcasts expecting the ad revenue would

follow– What is the true cost to reach viewers?

Security

• Digital Rights Management

Intelligence

• You must get accurate, reliable and useful usage and audience intelligence

• You can’t underestimate the importance of constantly measuring the success of your business.– Server logs

• Total megabytes transferred• Views by clip, visitor and time period• Player and version type• Average view duration

Intelligence 2 of 2

– Server logs continued• Maximum number of simultaneous users• Unique users• Most frequent visitors• Storage utilization• Total number of user sessions• Maximum number of simultaneous users per clip• File popularity• Successful requests, failed requests, incomplete file

transfers

Quality

• Garbage in, garbage out• Today’s users expect to give up some quality

in the image when compared to television• The issue is not just encoding choices, but the

entire delivery path. Servers, routers, wiring, and the entire infrastructure must be examined

Four components to a Digital Media Business

• Licensing the technology• Securing the content• Distributing the content• Quality metrics

– Getting the message acrossor

– Getting the consumer to pay

What player do you choose?

Some Examples of Digital Media on the web

• iTunes• MSN• AOL• Yahoo!• YouTube• Google Video• But wait, there is more

What is Brightcove?

Brightcove

• Presenting video on the web is more than just recording, editing and publication

• You need the infrastructure and tools to widely distribute, syndicate, package and monetize video content

Brightcove 1 of 4

With Brightcove:• Create and start using an Internet broadband video

distribution channel, literally in a matter of minutes.

• Your channel maybe a collection of hundreds of videos in different thematic categories, or just one short clip.

• Brightcove supplies the tools and server space• Videos are .flv (Flash Video files)

Brightcove 2 of 4

• You can use canned players or create and modify your own, based on branding needs

• You can create playlists for your users, create RSS feeds and even let others republish your content for that truly viral video experience

• You can offer selected “players” to other sites, in essence syndicating your content, while controlling your drm and distribution

Brightcove 3 of 4

• Brightcove also allows you as a content publisher to earn a revenue from the profit that large channels such as AOL may in the future generate around your video

• For those smaller online video publishers that do not already have an ad sales department, Brightcove has set-up its own advertising network,

Brightcove 4 of 4

• On the minus side, as a content creator you can do all that Brightcove allows only from IE and only from a PC. At least for now. For viewing, all you need is Flash in any browser.

• http://www.brightcove.com/index.cfm• http://video.about.com/• http://www.mediastorm.org/

Additional QuckTime Notes

QuickTime

• The QuickTime Server runs only on Mac Hardware• Apple also offers the Darwin Streaming server and

that will run on Unix and Windows.• The nice part is Apple offers the Server software

for free.• RealServer can stream QT as can Sun’s StorEdge

Media Central

• Blog for Tuesday July 11– Review two of the Brightcove partners and

compare and contrast how they are implementing the technology

• Workshop – demo compression– demo creating a streaming metafile using Catalyst