Set-top box and digital TV

The term set-top box (STB) is widely used for consumer electronic devices capable to receive video content according to DVB standard and display it on TV. The development of IP networks and broadband/ADSL made possible to deliver a video content of good quality and to appear IPTV set-top boxes.

Digital TV standards

Digital television uses a bunch of DVB (Digital Video Broadcast) standards. Depending on signal source they are divided into the following:

  • DVB-S — digital video broadcast by satellite
  • DVB-S2 — digital video broadcast by satellite, standard updated on 2004
  • DVB-SH — digital video broadcast by satellite for portable and mobile devices
  • DVB-C — digital video broadcast by cable
  • DVB-T — digital video broadcast, terrestrial television
  • DVB-T2 — digital video broadcast, terrestrial television, standard updated on 2008
  • DVB-H — digital video broadcast, terrestrial television for portable and mobile devices
DVB standard Modulation type
DVB-S QPSK, 8-PSK, 16-QAM
DVB-S2 QPSK, 8-PSK, 16APSK, 32APSK
DVB-C 16-QAM, 32-QAM, 64-QAM, 128-QAM, 256-QAM
DVB-T 16-QAM, 64-QAM in combination with COFDM, hierarchical modulation support
DVB-T2 QPSK, 16-QAM, 64-QAM, 256-QAM
 

STB classification

All set-top boxes can be divided into four major groups depending on source of digital TV signal:

  • STB for terrestrial digital video broadcast (DVB-T)
  • STB for satellite digital video broadcast (DVB-S)
  • STB for cable digital video broadcast (DVB-C)
  • IPTV set-top boxes receiving video streams via IP network (Ethernet or Wi-Fi)

Set-top boxes with MPEG-2 transport stream support are quite widespread in Europe and USA. However in Russia it is planned to step right into MPEG-4 (H.264), which provides better compression ratio comparing to MPEG-2.

Typical STB architecture is shown on Pic.1


Usually, STB consists of:

  • Frontend which includes tuner and DVB demodulator. Frontend receives a raw signal from antenna or cable. The signal is converted by frontend into transport MPEG stream. There is also Digital Satellite Equipment Control (DiSEqC) module in case of satellite antenna setup
  • Conditional Access – CA. Conditional access module or smartcard slot performs real-time decoding of encrypted transport stream
  • Demuxer filters incoming DVB stream and splits a transport stream into video and audio parts. Transport stream can contain some special streams like teletext or subtitles
  • Separated video and audio streams are directed to corresponding decoders
 

 

Overview of processor (system on chip) producers for STB

Being oriented to the mass-production consumer electronics, STB chipset manufacturers are forced to integrate more peripherals in a chip and to produce lower cost single chip solutions for BOM reduction and cutting price of a final STB device. Usually, the chip inside STB consists of 3 or more cores: a general purpose application processor and additional DSP-like cores dedicated to audio and video decoding.

Let's give a short overview of major semiconductor companies which produce processors (system-on-chip) for set-top boxes:

STMicroelectronics

ST is a top semiconductor player for STB chipsets. Currently the company's portfolio has the following processors:

  • STi5100 — low cost interactive set-top box decoder
  • STi5188 — low cost free-to-air satellite set-top box decoder
  • STi5105 — low cost SD decoder for MPEG-2
  • STi5107 — low cost interactive set-top box decoder
  • STi5200 — low cost SDTV set-top box decoder for H.264/AVC and MPEG-2
  • STi5205 — high performance advanced SD decoder for set-top box
  • STi5300 — high performance set-top box decoder
  • STi5516 — low cost set-top box decoder
  • STi5517 — low cost set-top box decoder
  • STi7141 — HD decoder for interactive digital cable set-top box
  • STi7101 — low cost HDTV set-top box decoder for H.264
  • STi7105 — low cost advanced HD decoding IC for STB and iDTV
  • STi7108 — low cost advanced HD decoding IC for STB and iDTV
  • STi7167 — low cost H.264 decoder with integrated DVB-T/DVB-C demodulator for 'zapper' boxes
  • STi7710 — single-chip low cost high definition set-top box decoder
  • STi7200 — triple display, HDTV set-top box, dual decoder for H.264 and VC-1

All ST's processor family is using ST40 core architecture for general purpose processor (200-450Mhz) which is a variant of SH4 architecture. Video and audio decoding blocks are of proprietary architecture codenamed ST231. There are many development kits from vendor with Linux, WinCE and custom RTOS support - OS21 and additional software components named OSPlus.

 

NXP Semiconductors

This Dutch chipmaker company become an active player in STB chipsets (especially for DVB-T) after acquisition of STB business from Connexant. However, in October of 2009, NXP refocused on automotive IC business and sold its set-top box and digital TV assets to USA based Trident Microsystems.

  • Nexperia PNX8735 — low cost HD set-top-box decoder
  • Nexperia PNX8732 — low cost SD set-top-box decoder
 

Fujitsu

  • MB86H01 SmartMPEG-M — SD multi-standard decoder for STBs and PVRs
  • MB86H60 — HD multi-standard decoder, highly integrated SoC for HDTV receivers

Low-end MB86H01 part uses ARC Tangent-A4 200Mhz core for its general purpose processor, while high-end MB86H60 part uses ARM11 core at 320MHz. MPEG2, H.264 Video decoder and audio decoder processor have proprietary internal Fujitsu architecture. FAMOS - proprietary real time operating system for multi-standard MPEG decoding is available from Fujitsu with reference design kit.

Recently, Fujitsu has updated its H.264/MPEG-2 HDTV Decoder offering with MB86H61 (an improved version of MB86H60):

  • MB86H610 Standard version of Free-To-Air STB/PVR including support for CI+
  • MB86H611 Embedded CAS version for PayTV applications
  • MB86H615 Shrunk version with reduced features set and QFP256 package
  • MB86H618 Extended temperature version, AEC-Q100 compliant
 

Renesas Electronics

This is a product line from NEC Electronics before merger in April 2010.

  • EMMA2 set-top box decoder family
 

Broadcom

Broadcom — middle cost processors for IPTV set-top boxes.

  • CM7038 Dual High Definition Digital Video System-on-Chip Solution for Cable, Satellite and DTV
  • BCM7043 HD/SD AVC/MPEG Video/Audio Encoder and Transcoder/Transcaler/Transrater
  • BCM7115 Single-Chip Cable Set-Top Box with PVR
  • BCM7118 Single-Chip Digital Cable Set-Top Box with DOCSIS® 2.0 and Channel Bonding
  • BCM7309 Single-Chip Back-End Set-Top Decoder
  • BCM7400 Dual AVC/MPEG-2/VC-1 HD Digital Video Decoder for Satellite, IP and Cable
  • BCM7403 Multiformat HD Digital Video/Audio SoC for Satellite, IP and Cable DVR STBs with Watch-and-Record DVR
  • BCM7404 AVC/MPEG-2/MPEG-4/DivX®/VC-1 HD Digital Video SoC for Satellite, IP and Cable
  • BCM7405 Multiformat HD Digital Video/Audio SoC for Satellite, IP and Cable STBs with Picture-in-Picture
  • BCM7410 HD Multiformat STB SoC with MoCA® Integrated for Low-Cost Gateway or Client STB Decoder
  • BCM7420 Dual HD Multiformat STB SoC with MoCA® Integrated Whole-Home Media Center Gateway System
  • BCM7452 AVC/MPEG-2/VC-1 HD Decode/SD Display SoC Solution for DVRs
 

Sigma Designs

Sigma Designs — middle cost processors for IPTV set-top boxes.

  • EM8620L family provides highly-integrated solutions for products requiring standard-definition and high-definition MPEG-4.10 (H.264), SMPTE 421M (VC-1), WMV9, MPEG-4.2 and MPEG-2 decoding
  • SMP8630 family provides highly-integrated solutions for products requiring high-definition MPEG-4.10 (H.264), SMPTE 421M (VC-1), WMV9, MPEG-4.2 and MPEG-2 decoding
  • SMP8640 family provides highly-integrated solutions for products requiring high-definition MPEG-4.10 (H.264), SMPTE 421M (VC-1), AVS, WMV9, MPEG-4.2 and MPEG-2 decoding
  • SMP8650 family provides highly-integrated solutions for products requiring high-definition MPEG-4.10 (H.264), SMPTE 421M (VC-1), AVS, WMV9, MPEG-4.2 and MPEG-2 decoding
 

NationalChip

NationalChip - a strong player on China and Asian markets, which has a set-top box IC portfolio for standard definition and MPEG2 video decoding:

  • GX1xxx – demodulator IC series (DVB-T, DVB-S, DVB-C, DTMB+DVB-C, ABS-C)
  • GX3xxx, GX2xxx – video post-processing and MPEG2 decoder IC series
  • GX6xxx – demodulator, video post processing, MPEG2 decoder System-on-Chip series
 

ALi Corporation

This is another Asian manufacturer:

  • M3501 – DVB-S/DVB-S2 demodulator IC
  • M3602 – HD, MPEG-2, H.264 set-top box SoC
  • M3381 – SD, MPEG-2, H.264 set-top box SoC
 

 

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