COM 597Streaming Media Lecture 3 June 27, 2006
Streaming v. Streaming As we discussed last week, the term “Streaming Media” has become somewhat of a catch-all phrase for digital media distributed over an IP network This is technically inaccurate
Streaming v. Streaming IBM’s definition to delineate the different types of digital media works well Digital media is unstructured content – audio, video, and images – that cannot be stored in a traditional database. The two major segments of digital media are: Media that has “intrinsic value” or in other words value that is inherent to the media itself (e.g. movies, documentaries, and music videos) Media that has “business process value” where the media becomes valuable due to the context in which it is used (e.g. training and corporate communications.)
So for the purpose of this class we will be exploring “Digital Media” over the course of the term. Tonight we will be studying… Streaming Media.
What is a webcast? Webcasts can include audio, video and other data like PowerPoint, animation, and even whiteboard applications Many webcasts also include some form of communication between the audience and the talent or host.
Some advantages of webcasting over traditional broadcasting Lower cost of entry Unlimited spectrum – don’t need a license from the FCC Not limited by geography Can be targeted to a specific audience
Some of the disadvantages of webcasting Smaller audience Incremental cost per viewer Quality
Many business and education enterprises are deploying webcasting as a cost-cutting enterprise for both internal and external communication
What is streaming media and how does it work Webcasting is a specialized application of streaming media technology Streaming enables real-time (or close to it) delivery of media across a network This technology is similar to how the web delivers web pages, with one big difference: Web servers download files, streaming media servers stream files. Downloaded files are displayed after the entire file has been delivered
Streaming files play as they are delivered (this is not progressive download)
For large files the advantage of streaming are: Real time Control/interactivity (real-time presentations) Security (not stored on the hard drive) Live broadcasting
Bandwidth Capacity YMMV
Bandwidth of individual audience members determines how the webcast should be encoded The bandwidth at the site determines how much data can be sent to the distribution servers The aggregated bandwidth used determines the bandwidth charge
Load balancing Streaming media servers receive the incoming stream from an encoder (or encoders) and then may distribute the media to the audience. A server may also send the stream to other servers for load balancing and redundancy Load balancing is where a number of servers are used to distribute a webcast to improve performance and reliability
Protocols To facilitate communication there are standardized protocols used so the servers, players and encoders work properly For example “http” stands for hypertext transfer protocol. “ftp” stands for file transfer protocol “rtsp” stands for real time streaming protocol This is the most common protocol used, but not the only one.
Business Considerations Who is the intended audience for this webcast? What is the purpose of the webcast? What is the need? Is a webcast the most efficient way to distribute the message? Where is the webcast taking place? When is the event? Why? Is there really a need to do this or is it just “cool”? Will the webcast pay for itself with new revenue or through cost savings?
If you have good answers to the previous questions then ask these: Does it have to be live? What are the cost considerations? What is the ROI? Are there legal considerations? Live is always more expensive than recording and archiving it for later use.
What are possible events with time sensitive content? Breaking News Distance Learning Stock Market activities Music Events Sporting Events Community Event
Where are you going to spend your money? Budget will determine both the quality and reliability of a webcast Single or three camera shoot? – Your most exorbitant line item will be your production costs. Bandwidth costs
Where are you going to spend your money? Unlike radio or broadcast television, you must pay for the additional bandwidth required each time someone tunes into your webcast. The prices are astoundingly random based upon what carrier you use. Figure somewhere between $75 and $35 per megabit from network carriers. Shop around before you buy.
How do you know your bandwidth needs? Measured in bits per second (bps) of the information sent concurrently Because these numbers get big fast we use Kbps and Mbps A kilobit is 1024 bits Megabit is 1024 Kilobits (1024x1024) or 1,048,576 bits
How do you know your bandwidth needs? Here is the rub… Data is measured in bytes, not bits. There are 8 bits to a byte A gigabit is 1024 Megabits So…
Let’s say you have a show There are 100 viewers for your webcast They will all watch a 300Kbps stream 300Kbps x 100 = 30000Kbps This number is too unwieldy, so let’s figure out how many Megabits per second
30000 / 1024 = 29.3 Mbps Add about 20% for overhead and you land at: 35Mbps sustained bandwidth
But how long is your show? Let’s say it is 1 hour 35Mbps x 60 seconds per minute x 60 minutes per hour 35x60x60 = 126000 Megabits
But wait, we need bytes, not bits. 126000 / 8 = 15750 Megabytes The number is still too unwieldy so divide by 1024 to get Gigabytes 15750 / 1024 = 15.38 gigabytes
How do you know your bandwidth needs? So when you talk with a content delivery network about prices you can confidently state that you need approximately 35 megabits of concurrent capacity, and you expect to transfer about 16 gigabytes of data.
Usage Logs and Metrics They will vary based on the CDN you chose How many watched How long they watched Where they were from
Rights Do you have rights to the images and music used in the webcast? Do you have rights to the graphics and video used? How likely are you going to be sued? Do you have releases from all people and locations used in the webcast? Do you have a labor union to deal with either on site or licensed material?
So how are webcasts produced? The process is essentially the same as producing a program for broadcast, except the signal is sent to a streaming encoding solution instead of a broadcast tower or cable system. The same approach of good audio and video engineering applies to both. Crap in equals crap out.
The difference between an on demand streaming file and a webcast is there is no room for error. It is live so you need to have it tested and working prior to the event. Because it is a real-time event, it will affect every phase of production.
This includes: Planning – justifying costs, location, tools, crew Production Encoding Authoring – connecting the audience to the webcast via a link on a web page Distribution – securing an infrastructure that is robust for your needs Remember: If you have not planned it right your webcast can grind to a halt. This can be a career-ending move. Be certain you have not only created a plan, but you have redundancy in place in case of failure
Where do we start? Step one: Plan – 95% of the work happens before the event Step two: Plan some more Step three: Check out your location – do you have power? How do you connect to the web? What are the acoustics like? Who are your points of contact? Step four: Change your plans
Where do we start? Spend a significant amount of time planning Do a site check Acquire and test all the equipment necessary for the webcast Acquire and test all the encoding hardware necessary, bring extra Examine and test your streaming server architecture – any license issues with the number of streams you expect to distribute simultaneously? Do a body count – do you have enough of the right people in the right jobs? Test connectivity on site BEFORE the webcast This includes testing the broadcast equipment, load-testing the server, test the links on the website
Where do we start? Bottom line: Take the time to plan Keep it simple Bring two of everything Be kind Start early
Business considerations As discussed earlier: Who is your audience? Do you really NEED to do a webcast? Is there a better solution? How much might it cost? What is the return?
Production Considerations Do it yourself or outsourcing Which parts? How do you find a partner? Production Partner Distribution partner Marketing partner Ask to see examples of their work
Some nasty questions to ask a potential encoding partner Do they know how to set up redundant encoders? Have they had experience bonding ISDN lines and knowing how to force them to dial long distance? Do they know how to remix the audio and switch between multiple video inputs? Do they know how to work with the camera technicians to have the video shot in a way that works best for a webcast? Will they advise you on what backgrounds and colors work best for streaming media? From “Hands-On Guide to Webcasting”
Pricing and Providers Entering into an agreement with a CDN (Content Deleivery Network) is not unlike buying a car There is lots of smoke and mirrors and no one can agree on what to call the same service from provider to provider
Two primary charge models for webcasting distribution: RSVP Model – charged based on the number of simultaneous streams used at any one given time. Usually a reserved number of streams Throughput model – charged based on the total amount of data delivered over the network during the course of the event.
The factors common to any charging model would be: Length of the event Time of the event Number of formats Number and size of bit rates Geographic distribution
Additional fees may include: Some sort of registration to authenticate a user Pay Per View Late notice or last minute event
Who to talk to about a CDN Solution Limelight Networks (www.limelightnetworks.com) Akamai (www.akamai.com) Mirror Image (www.mirror-image.com) SAVVIS (www.savvis.com) VitalStream (www.vitalstream.com) For Small Business PlayStream (www.playstream.com) For Financial Business Thompson (www.thompson.com) ON24 (www.on24.com)
Equipment and crew What is your video source (type and fps of video feed)? What is your audio source? Are you renting the gear? Purchasing it? Are you hiring a 3rd party company to produce the video feed?
Some of the gear you will need: Microphones (Lav, handheld, shotgun, spares) Cables of many types Camera Audio mixer Video switcher if multi-camera Distribution Amps (so you can split your feeds) Isolating transformers and humbuckers Batteries Encoding computers Monitors Communication system (for crew and back to broadcast operations center)