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      Digital TV  
 

Digital TV (DTV) offers not only better audio and video quality but also, enhances the TV viewing experience. High definition video, surround sound audio, multiple audio/subtitle language selection for a program, interactive TV etc. are the few features of DTV. Traditionally,TV is presented mainly via 3 mediums, Terrestrial, Cable and Satellite and so is the DTV. There are standardization bodies which are responsible for defining, standardizing and recommending the DTV broadcast. For example,DVB, ATSC, Opencable, ISDB etc...

All the standardization bodies will ensure the DTV transmission (broadcasters) and DTV reception (DTV manufacturers) agree to a common standard and are compatible.

 
      DVB (Digital Video Broadcast)  
 

DVB is the forum consisting of broadcasters, CE manufacturers, Network operators, Government institutes and others. DVB as a group set the standard guidelines and recommendations for DTV broadcast and reception. DVB defines audio, video, subtitle, teletext, service information, RF modulation etc. standards and recommendations for terrestrial, cable and satellite modes of DTV transmission and reception.

 
      DTV standards and specifications  
 

MPEG-2 Transport Streams

DVB based DTV broadcasts mainly use MPEG audio and video encoding standards. However, other compression standards are also provisioned to be used. For content delivery, i.e. Digital TV (audio- video), Digital Radio services etc. DVB uses MPEG-2 transport streams (MPEG-2; ISO/IEC 13818-1 System Standard).

MPEG- 2 System (ISO/IEC 13181-1) standard defines bit-stream syntax for compressed audio and video content for storing purposes i.e. program streams and for broadcasting purposes i.e. transport streams. Program streams syntax is optimized for error free conditions while, transport stream syntax is designed for handling erroneous conditions. DVD-Video discs use MPEG-2 program stream syntax for storing compressed AV content. DVB uses transport streams syntax which are designed for error resilience. The beauty of the MPEG-2 system standard is that it is very generic and future proof. Standard has bit stream syntax with some of the syntax fields left reserved or unused, considering future feature requests that might arise. So, it can easily meet the demands for new features that might arise in the future years.

Finally in summary, considering DTV broadcasts,
MPEG-2 standards defines audio and video compression and delivery mechanism. DVB standards set the additional rules and recommendation for DTV broadcast based on MPEG standards.

Why can’t we use MPEG directly why do we need DVB on top of it?
As MPEG is generic standard and gives wide range of options, DVB uses part of the MPEG standards. Also, DVB extends and add its own additional requirements needed for DTV broadcasts, like defines, teletext, subtitles, RF broadcast etc. Basically, DVB uses audio and video compression and multiplexing (transport stream) part from MPEG standards. Also, defines and uses reserved/undefined fields in MPEG-2 system standard bit stream syntax for its own defined features.

 

 
  Standards Standards and Specifications:
MPEG
  • H.262 / ISO/IEC 13818-2
  • H.264 / ISO/IEC 14496-10
  • SMPTE 421M
  • ISO/IEC 11172-3
  • ISO/IEC 13818-3
  • ISO/IEC 14496-3
DVB
  • TS 101 154
  • TS 102 154
  • TS 102 005
  • TS 102 366
  • TS 102 114
 
      Digital Terrestrial Television (DTT) - DVB-T in Europe  
 

A country which adopts DVB for DTT considers  its own features list which they are going to adopt from huge list of DVB features. These are known as country specific requirements. For Ex: UK has D-Book defining DTT in UK. Italy has DGTVi D-Book. E-Book defines and recommends how DTT to be in EU.

 
  DTT in EU  
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