[linux-dvb] Re: Frontend IP based

[Ralph Metzler <rjkm@metzlerbros.de>]

jp writes:
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 > IMHO For a LAN, RTP isn't worth it.
 > In fact we mcast TS over UDP for 3 router hops with no problems.
 > I think we've got customers doing even more than that.
 > 
 > I've never seen RTP make any improvement to traffic.
 > There must be instances where it makes sense perhaps unicasting over the
 > interweb. But not on small multicast networks.
 > 
 > Thomas Sailer wrote:
 > | On Thu, 2004-12-16 at 10:54 +0100, Marcus Metzler wrote:
 > |
 > |
 > |>Just to clarify what you are talking about. You mean a frontend where
 > |>the data does not come from the tuner but via the network card, right?
 > |>Would you use RTP or some other protocol?
 > |
 > |
 > | I thought about building some hardware that just encapsulates TS packets
 > | into UDP frames. This can be done with a small FPGA and an ethernet PHY
 > | chip, so this is simple. VideoLAN seems to be able to do this too.
 > |
 > | I don't see what RTP buys you. It's certainly more complex.


I think the original question was only to clarify if IP over DVB or
DVB over IP was meant.

Anyways, regarding RTP, it has the advantage to provide time-stamps. 
Of course most cards do not deliver time stamps for the incoming TS
packets (but some do). So, most RTP servers programs derive the 
time from the PCR and interpolation which kind of defeats their purpose.
Playback usually still works fine with this kind of streams if enough
buffering and other syncing tricks are used.


Ralph