Switched Digital Video (SDV) - The Benefits

Telco and cable operators are recognizing numerous benefits of SDV and getting more attractive to deploying it. Prior to SDV, the digital video broadcasting started with satellite DTH (Direct To Home) which gave to the cable industry the ability to provide a mixed of analog and MPEG-2 digital services as follows:

• 70 to 90 analog 6 MHz channels


• 8 to 10 MPEG-2 simulcast standard definition (SD) 6 MHz QAM channels


• 8 to 10 high definition (HD) 6 MHz QAM channels


• 4 to 6 video-on-demand (VOD) 6 MHz QAM channels


• 1 to 2 high-speed data (HSD) and voice-over-IP (VoIP) channels

With DTH the badwidth is wasted and, with the exception of the premium channels, the MPEG-2 standard definition (SD) programs are predominantly simulcast analog channels. The MPEG-2 High Defination (HD) content consists of between 15 to 30 HD programs and is also, in large part, duplicating the SD content. Worse, MPEG-2 HD content is a bandwidth hog, where only two to three programs can be put in one 6 MHz QAM channel, so there is limited space to add more HD content.

SDV optimizes the bandwithd and uses 50 to 75 percent less bandwidth as compared to traditional broadcast model. For broadcast services, all services go to all homes all the time, regardless of whether anyone is watching those services. The SDV provides dynamic switching of digital services hence the cable operators are able to broadcast only the programs that are requested by the subscribers. Niche programs switched at service group level instead of broadcast to all subscribers. Unwatched digital tier programs will no longer waste valuable bandwidth.

They can monitor the channel programming and determine if a requested program is already being watched. If so, the requested program is placed into the group of the realted viewers. If there is no one watching a show, then the operator removes that show from the list of broadcast which creates more bandwidth for other programs.

The SDV can be desinged to be intgelligent to determine which video format the subscriber's reciever is capable of and based on this data broadcasts the best format to subscriber. For example, the oprerator can determine whether to send MPEG2 or MPEG4 based on the subscriber's set-top-box capability.

MPEG4 format is twice as faster as MPEG2 and provides High Defination (HD). Of course the subscribers want to see all program in HD. This will force the cable operators to provide MPEG4 capable set-top-boxes to the subscribers. Mirgrating from MPEG2 to MPEG4 can cost billions of dollars and has to be done in phases. The SDV can provide efficient mechanism to cable operators to migrate from MPEG2 to MPEG4 in phases. Also see SDV Architecture for more info.

The following lists benefits SDV can offer cable operators.

SDV Benefits:

• Bandwidth optimizmation. More HD Services. More Digital Simulcast.


• Provides ability to monitor channel programming effectively.


• Provides ability to transmit the best format to the subscribes.


• Delivers the requested content to subscribers in real-time.


• Provides efficeint mechanism for migrating from MPEG2 to MPEG4.


• Facilitates the creation of new services.


• More International & Special Interest Content


• Boosts total number of channels available.


• Enables market-specfic niche, including high definition programming.


• Increases the level of concurrent video on demand (VOD) sessions being served to various nodes.


• Provides methods for advanced targeted ad-insertion solutions.


• Frees up bandwidth for data delivery. Increased high speed data [internet / VoIP] via DOCSIS 3.0 channel bonding

About me:

bruce atlasi is a professional computer engineer, skilled in telecomm and datacomm technologies and architecture. He has diverse working experience with many telecomm start-ups and fortune 100 companies, including Cisco Systems, IBM, and Siemens. He regularly blogs on About Telecomm site.