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Inside Cablevision's 'RS-DVR'

Cablevision is playing for keeps with its controversial 'Remote Storage' DVR

Jeff Baumgartner

April 11, 2007

6 Min Read
Inside Cablevision's 'RS-DVR'

Now that Cablevision Systems Corp. (NYSE: CVC) has appealed a judge's decision that its "Remote Storage-Digital Video Recorder" (RS-DVR) infringes on studio and programmer copyrights, it's clear now more than ever that the New York-based MSO is playing for keeps. (See Net DVR Still Appealing for Cablevision.)

The fight is over whether there are separate ownership rules when content is stored on a service provider's storage system delivering the content through a networked DVR, rather than the user's own equipment. Cablevision once again will take the old Sony Betamax decision to task, contending that the RS-DVR should be protected in the same way that an in-home DVR is today. Cablevision argues that its RS-DVR is no different than an in-home DVR, because if 1,000 customers tap the RS-DVR to record a specific program, the system is designed to make 1,000 individual copies. Further, each copy is accessible only to the customer who made the original recording request.

If Cablevision's appeal is successful, it could serve to define how other cable operators move ahead with their own network-DVR services. Likewise, a successful appeal could be a boon for more than a handful of vendors that are linked to Cablevision's RS-DVR project.

Privately, some observers believed Cablevision's motive with the RS-DVR was to get programmers to the negotiation table to carve out network DVR deals -- akin to the axiom that it is easier to ask forgiveness than it is to obtain permission.

But that argument becomes a tougher sell when one considers the technical groundwork Cablevision had already completed on the project. Much of that detail is copiously outlined in a 38-page decision handed down on March 22 by U.S. District Court Judge Denny Chin, who ruled that Cablevision's RS-DVR would violate the copyrights of a raft of plaintiffs, including Disney, Paramount Pictures, Twentieth Century Fox, CNN, and NBC.

A look through the decision clearly indicates that Cablevision had taken the necessary technical steps to deploy the RS-DVR, though it stopped short of doing so, agreeing to mothball the project pending the judge's decision.

Now that this innovative and controversial service appears to be back in play, here, according to the judge's decision, is a brief synopsis of how the platform would work and the roles some vendors played in its creation.

Getting started
The service originates at the "BarcoNet" (Scientific Atlanta bought BarcoNet in late 2001), a closed circuit network that receives Cablevision's linear programming. That programming, called the aggregated programming stream (APS), comprises packets of data, with each packet tagged with a program identifier (PID).

The system then splits the APS into two streams, the second of which is piped to the BigBand Networks Inc. (Nasdaq: BBND) Broadband Multimedia Router (BMR). There, the BMR "clamps" the stream, converting the variable bit rate (VBR) stream into a constant bit rate (CBR) stream. (Note: the CableLabs CBR spec for standard-definition VOD streams is 3.75 Mbit/s; the CableLabs "safe harbor" bit rate for HD-VOD is 15 Mbit/s.)

During the clamping process, portions of the program are sent to the BMR's buffer memory. The BMR then encapsulates the information by converting the APS into a number of single program streams and placing packets in those streams into larger packets called User Datagram Protocol (UDP) packets. Each UDP packet is assigned a port number that identifies the TV channel to which it belongs.

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Straight through the heart
Then the "heart of the RS-DVR" (the primary server) takes over. In this case, Cablevision had selected servers from Arroyo Video Solutions, which is now part of Cisco Systems Inc. (Nasdaq: CSCO). (See Cisco Snatches VOD Vendor Arroyo.)

The BMR sends streams into these servers, where programming is recorded and stored for later playback. According to court documents, each Arroyo/Cisco server can service up to 96 Cablevision customers. The MSO, according to the decision, had initially determined that each RS-DVR customer would get 80 gigabytes of storage, but later decided to double it to 160 gigabytes.

The Arroyo/Cisco server then reads the streams into the "primary ingest buffer," where content is stored for up to a tenth of a second. The primary ingest is designed to hold 6,000 packets at any one time, equal to about three frames of video.

Recording
Under Cablevision's RS-DVR model, customers can set recordings by selecting a program from the interactive program guide (to set advanced recordings) or by simply pressing the "record" button on the remote control (to record a show already in progress).

Record commands are relayed to the ADS server at the headend, where the system verifies that the customer is authorized to receive the program to be recorded. The system will send an error message if a customer tries to record an HBO program but the customer does not subscribe to the service.

If recording is approved, the ADS queries the Oracle Production Server (OPRD), which maintains a list of programs that the customer has requested for recording. An asset ID is then assigned by another server, dubbed the "Asset Management and Publishing System (AMP)."

Once the ADS has the asset ID for a program, it communicates that data to a Vitria Technology Inc. (Nasdaq: VITR) server. That server, in turn, aggregates recording requests and relays the information to the Arroyo/Cisco server.

Then something very important to Cablevision's argument in the case happens.

When it's time to record a program pre-selected by customers, the Vitria server sends a unified list of all of those requests to the ingest element of the Arroyo/Cisco server. A copy of the program is then made for each customer who requested the program to be recorded. If 1,000 customers requested to record an episode of HBO's The Wire, 1,000 separate copies of that episode are made. Further, each copy is "uniquely associated by identifiers with the set-top of the requesting customer," as described by the ruling's description of the RS-DVR architecture.

Once a copy is made, the customer will find it ready for playback on the set-top's IPG.

Playback
Here, the set-top communicates with yet another server, the Enterprise Session Resource Manager (eSRM), which manages the playback process and ensures that the playback command is indeed valid. This component also reserves the necessary bandwidth on the cable system. (For more on this emerging technology, see Camiant Puts Video Policy Gear Into Play .)

The Arroyo/Cisco server locates the copy of the program associated with the customer and delivers it to the "streaming buffer." From there, a Ciena Corp. (NYSE: CIEN) switch routes the stream to the QAM serving that particular customer.

It's at this point that the customer can watch the recorded program and can move around the asset using trick modes (pause, fast-forward, rewind, etc.).

Or, at least, that's the theory.

— Jeff Baumgartner, Site Editor, Cable Digital News

About the Author(s)

Jeff Baumgartner

Senior Editor, Light Reading

Jeff Baumgartner is a Senior Editor for Light Reading and is responsible for the day-to-day news coverage and analysis of the cable and video sectors. Follow him on X and LinkedIn.

Baumgartner also served as Site Editor for Light Reading Cable from 2007-2013. In between his two stints at Light Reading, he led tech coverage for Multichannel News and was a regular contributor to Broadcasting + Cable. Baumgartner was named to the 2018 class of the Cable TV Pioneers.

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