How Live Streaming works
Category: Live Streaming  
Level 3’s Live Streaming platform provides support only for Adobe Flash format. Although Level 3 can provide signal acquisition and encoding services as part of a larger holistic solution, the scope of this document strictly deals with the CDN streaming services capability.
Flash Media Services
The Level 3 streaming platform uses the Flash Media Server 3.0.1 application, which ensures compatibility with the H.264 codec. From a Live Flash streaming codec standpoint, customers may elect to use either On2’s VP6 codec or the new MPEG-4 based H.264 codec. Most customers will opt to use either the On2 Flix software, available for a nominal fee directly from On2, or Adobe’s Flash Media Encoder, which is freely available for commercial use.
Flash Media – High Level Workflow Process for Live Push-Based Streaming
Step 1: Customer Pushes Content to Level 3 Flash Publishing Point
The customer pushes the live event via their Flash Media Encoder to a Level 3 Flash Publishing Point. Level 3 will provide a URL where the end user can push the stream to and subsequently an URL which the customer can embed into their Flash player distributed to their end users.
Step 2: End User Requests Live Flash Stream
End users are directed to the closest available Level 3 edge Flash streaming server by way of the provided Level 3 stream link.
Step 3: Level 3 Flash Server Subscribes to Live Feed
The Level 3 edge Flash Media Server (FMS) will subscribe to the Level 3 FMS Publishing Point server used to acquire the live signal feed. If the edge server is already subscribed to the live feed, it will not have to re-subscribe to the live feed.
Step 4: Deliver the Live Flash Stream
Once the Level 3 edge FMS receives enough information to fill its buffer, it in turn will begin playback to the end user within the customer’s Flash player.
Multipoint Publishing
The Level 3 Live Flash streaming service has been designed to pull the live feed from the customer’s Flash Media Server- also known as Multipoint Publishing. Adobe’s Flash Media Development server is available free of charge from Adobe and can be commercially be used to support live signal acquisition. Under this scenario, the Flash Media Server Developer server can be used as a local Flash Publishing Point. The benefit of using Multipoint Publishing is that it provides the customer flexibility and scalability to their streaming application. As with the live Windows Media workflow, the customer’s Flash Media Server must be available to Level 3 on an publicly available IP address.
Currently, Level 3 does not allow customers to deploy any customer specific server-side code on the Level 3 Flash streaming servers nor inject any data messages into the outbound stream. Sometimes, customers will want to insert information into the Flash stream to support advertising, tracking beacons, or SWF interactivity. By using Multipoint Publishing, it allows the customer to insert custom information into the live Flash data feed. For these reasons, Level 3 strongly recommends Multipoint Publishing as the main method of live Flash signal acquisition.
Flash Multipoint Publishing Streaming – Live Streaming Workflow
Step 1: Customer Pushes Content to Internal Flash Media Server
The customer pushes the live event via their Flash Media Encoder to a local Flash Media Server machine. The customer’s Flash Media Server must be exposed via a publicly addressable IP address.
Step 2: Level 3 Acquires Live Signal Feed
Level 3’s streaming service will acquire the live Flash feed by initiating a pull from our Flash Media Server(s). In the case where there is a primary and a backup feed, Level 3 will use disparate server locations to ensure diversity. Level 3 will provide the customer with a URL which the customer can embed into their SWF file where end users can retrieve the live stream feed from the Level 3 streaming network.
Step 3: End User Requests Live Flash Stream
End users are directed to the closest available Level 3 edge Flash streaming server by way of the Level 3 provided stream link.
Step 4: Level 3 Flash Server Subscribes to Live Feed
The Level 3 edge Flash Media Server (FMS) will subscribe to the Level 3 FMS Publishing Point server used to acquire the live signal feed. If the edge server is already subscribed to the live feed, it will not have to re-subscribe to the live feed.
Step 5: Deliver the Live Flash Stream
Once the Level 3 edge FMS receives enough information to fill its buffer, it in turn will begin playback to the end user within the customer’s Flash player.
Flash Media Encoder Publishing (Limited Availability)
Not all customers have the ability or need to establish a Multipoint Publishing workflow. In recognition of this, Level 3 can support a workflow where the customer can directly push their content to a Level 3 FMS Publishing Point without having to stand up their own FMS Publishing Point. Customers using this method of live signal acquisition cannot inject their Flash streams with metadata unless it is done via their Flash encoder. At this time, push-based signal acquisition for Flash is in Limited Availability meaning that we are supporting only a limited number of Flash Publishing Points. Please consult your account representative if you wish to explore using this ingest option.
Flash Media – High Level Workflow Process for Live Push-Based Streaming
Step 1: Customer Pushes Content to Level 3 Flash Publishing Point
The customer pushes the live event via their Flash Media Encoder to a Level 3 Flash Publishing Point. Level 3 will provide a URL where the end user can push the stream to and subsequently an URL which the customer can embed into their Flash player distributed to their end users.
Step 2: End User Requests Live Flash Stream
End users are directed to the closest available Level 3 edge Flash streaming server by way of the provided Level 3 stream link.
Step 3: Level 3 Flash Server Subscribes to Live Feed
The Level 3 edge Flash Media Server (FMS) will subscribe to the Level 3 FMS Publishing Point server used to acquire the live signal feed. If the edge server is already subscribed to the live feed, it will not have to re-subscribe to the live feed.
Step 4: Deliver the Live Flash Stream
Once the Level 3 edge FMS receives enough information to fill its buffer, it in turn will begin playback to the end user within the customer’s Flash player.
Integrating with Internet Traffic Manager
Level 3 makes use of its Internet Traffic Manager (ITM) to provide global load balancing capabilities across the streaming platform. The fplive.net hostname is simply pointed to resolve to the ITM platform via a CNAME such that it can provide real-time decision logic on which available Level 3 stream cluster is the closest to the end user. Since the fplive.net hostname is nothing more than an abstraction to the streaming IP addresses, this provides Level 3 with some operational efficiencies to add and remove streaming servers into the platform without the customer having to make any modifications to their streaming links.
Some customers may want to obfuscate the fact that Level 3 is powering their streams. In such instances, customers may wish to create their own vanity streaming hostnames and then CNAME that hostname over to the Level 3 provided hostname. As a reminder, you will need to have a specific vanity hostname per format type. W3C best practices dictate that double CNAMEing is not prudent; however, this practice will not affect most end users and is used quite commonly.
e.g.
video.example.com CNAME 1d examplewms.fplive.net
If using a vanity hostname, the customer will still need to use the Content_Location directory path when
constructing their URIs; however, the double CNAME will effectively hide the fact that Level 3 is
powering the streams. The media player will only display the customer’s vanity hostname and not display
the chased hostname to *.fplive.net back to the media player.
NOTE: if an end user were to query the vanity hostname using DIG, the fplive.net domain will be returned in the answer as the nameserver will chase the CNAME in order to return an answer to the end user. Level 3 recommends that customers using their own vanity hostnames use a TTL in their DNS entry of at least 1 day to minimize DNS lookup times for the end user.