[vdr] reel netclient

Georg Acher acher at in.tum.de
Mon Apr 13 16:58:16 CEST 2009


On Mon, Apr 13, 2009 at 04:03:02PM +0200, Matthias Müller wrote:
   
> I have no netceiver to play with and didn't look at the sources. But 
> it's nice to see a real world use for IPv6 in consumer hardware (if you 
> can call the reel boxes consumer hardware, it's probably only for a 
> limited, but sophisticated market.

The client and the also available standalone NetCeiver should bring it more
to the "masses" as the price will be comparable to typical HDTV receivers.

> Does it just use a fixed multicast-address to receive the stream and if 
> yes, how is the communication to the tuner realized? Is this something 
> reel-specific or could this be used to start a unified streaming-concept 
> for vdr based on standards (and using IPv6 to avoid all that ugly IPv4 
> stuff...)

It is a proprietory protocol in the sense as it is no standard. When there
are so many IPTV standards to choose from, why make not a new one? ;-) At
the time we started, DVB-IPTV was not even named and still I think it is so
bloated that it cannot be efficiently used to use cheap hardware as a
server.

However, our protocol uses standard protocols like MLDv2 just with a
different interpretation to make it light-weight and use hardware supported
streaming. In the end, one NetCeiver can stream up to 6 full S2-transponders
(~40MByte/s), only the zapping time increases a bit... Do that with a PC :p

The protocol translates (almost) all DVB specifics to ethernet, so it was no
problem to wrap it back to DVB-API. The multicast address is not static but
contains all relevant reception parameters. The basic communication only
exchanges a few MLDv2-messages (no XML), so it can be processed very fast
and also gains from MLDv2-aware switches. Only tuner capabilities and tuning
states (SNR, lock, ...) are transmitted regularly in a side band via XML on
a specific multicast address. That also allows zero configuration for the
client. We will write a "white paper" about the protocol, currently we just
don't have enough time...

For the client side, the sources will be published as GPL. Currently we use
a closed source daemon with a dvb loopback driver in the kernel, but that
makes it hard to fully use the tuner virtualization and costs some overhead
for small CPUs. Since we already have a native vdr plugin for that, the
network code will be then forced to be GPL anyway ;-)

-- 
         Georg Acher, acher at in.tum.de         
         http://www.lrr.in.tum.de/~acher
         "Oh no, not again !" The bowl of petunias          



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