[OpenWrt-Devel] DVB tuners

[Dirk Neukirchen]

On 14.05.2015 16:22, Charlie Smurthwaite wrote:
> Hi,
> 
> I am looking into set-top-box applications and wondered if you guys were aware of any devices with DVB functionality. I'm particularly interested in whether there are any Linux SoC devices with interfaces capable of handling multiple DVB tuners.
> 
> I would guess this could be handles using USB interfaces, but hoped there might be exampled of better ways to achieve it.
> 
> Thanks in advance,
> 
> Charlie
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> 

There are a "ton" of DVB capable SoC devices - ARM, MIPS or x86 that could potentially run OpenWrt or that
might be capable of running vanilla/upstream Kernel so porting to *almost* upstream OpenWrt is less painful.
(if you want tu run OpenWrt - you might run "normal" Linux or you have to stick with ancient vendor Linux)

Afaik black box DVB->IPTV boxes are also available targetting private (Inverto SatIP LNB, "Cable IP" from AVM)
users (up to normal broadcast use-case/multi-residential use-case). just to keep in mind as alternative

However dealing or developing in that area can get really painful because many 
hardware vendors willingly break their products to disable normal consumer features.
(Hollywood Studio guidelines or consumer features)

This is from some research + experiments running Linux DVB receivers.

"classic" Linux DVB SoC solutions from
- MIPS platform: VU+ (VU Plus), Dreambox Hardware having up to 4x integrated tuners
- ARM platform: Coolstream  up to 4 integrated tuners
- SH4 platform  (dont know)
have at least some Open Source projects & developers attached (Neutrino, Enigma, tuxbox projects)
but sometimes horribly old vendor Kernels.

DVB Set-Top boxes became "outdated" for some ppl in place of integrated TV (silently removing features due to DRM) OR new
streaming / Set-Top Box + USB solutions like:

- (SigmaDesign) Popcornhour boxes (some SDK were available
because there were some community packages but I remember this as very closed
from vendor barely providing any useful info on public sites)
"Maker" hardware like:
- (broadcom) Raspberry PI with kodi,OpenElec or OpenEmbedded/Yocto
- (Amlogic) S805 (Odroid-C1) S812 (several chinese vendors) (4x USB 2.0)
Experimenting/Flashing might be easier and faster because SD-Card boots.
Some modern distros like Archlinux for aarch64 can run on these too.

Main potential problems are:
- poor Network/IO performance (USB attached Ethernet, 10/100Mbit only) of "classic" DVB SoC
- reason for poor IO is hardware acceleration & default bit rate limits (CDROM,DVD speed, BluRay bitrate) 
or "common broadcast practise" (<3Mbit/s SD, <10Mbit/s HD for example)

- slow general purpose CPU (Hardware codecs on most devices) (classic DVB)
- USB attached tuners have issues like potential dropouts and electrical bus / ESD problems
- design compromise: RF frequency chip design affects sound I/O (different but similar problem
is the 2.4GHz and USB3 interference)

Notice that DigitialDevices offers miniPCIe DVB with multiple tuners
and there were IEEE1394 DVB tuners ("FireDTV") that were chainable on market.
APU 1D4 or next gen Soekris 68xx Atom "SoC" might be interesting.


PS: Most facts are from public info / reviews / "Prosumer" perspective only 
Since testing gets really expensive when looking at multi tuner/DVB solutions 
or embedded boards that might be capable or good solutions for "embedded" / small HTPC.
http://www.cnx-software.com/ seems to list/post about every obscure embedded "china" hardware
and often does multimedia hardware too.
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