[linux-dvb] DVB-H and dvbnet / MAC-broadcast address

Giovanni giluong at libero.it
Fri Mar 30 17:17:20 CEST 2007


Hi to everyone


Provided that I managed to receive the ESG bootstrap descriptors, to identify the multicast address the ESG is transmitted on and to receive the IP packets on the corresponding PID, I'm not able to decode the ESG containers carried on it.
The main problem is that the ESG I'm trying to decode is BiM encoded: could someone tell me how decode it or how to address this problem in some other way? 
I mean, if the .sdp files are carried within ESG containers, is it absolutely necessary to decode them or there's some way to identify them and skip the ESG decoding?
Moreover, I've read that .sdp files describing the streaming sessions could be transmitted directly over FLUTE sessions, without being encapsulated into ESG containers... Is this true?
And, in case it were, would the .sdp files directly announced in FLUTE FDT instances?

Thank you 

Giovanni



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---------- Initial Header -----------

>From      : linux-dvb-bounces at linuxtv.org
To          : linux-dvb at linuxtv.org
Cc          : 
Date      : Fri, 30 Mar 2007 14:38:16 +0200
Subject : Re: [linux-dvb] DVB-H and dvbnet / MAC-broadcast address







Dietmar Zlabinger wrote:

> Hi,
>
> I am looking for help on receiving DVB-H.
> I get to the point where the encapsulated IP is attached to a network 
> interface (as dvb0_0 using dvbnet -p <portnr>). At this stage I am 
> able to dump the UDP-packets received using tcpdump. But I am not able 
> to get that IP-multicast into VLC.
>
> I believe the problem is related to the fact that normally 
> IP-multicast uses the Ethernet broadcast address (ff:ff...) while in 
> dvb-h the destination mac is (partly) replaced by the dvb-h time 
> slicing information . Therefore the traffic is only received by the 
> network interface when it is in promiscuous mode (when using tcpdump), 
> but not when a normal program (like vlc) is trying to get multicast 
> frames out of it.
>
> My idea then was to modify dvbnet so that it replaces the "broken" 
> ethernet destination (is contains timeslicing-infos) by "ff:ff" so 
> that it goes through the network interface. But the actual code of 
> dvbnet does actually not handle the received data, the only thing that 
> program does is some ioctl(fd_net).
>
> Any idea who I could get the ethernet-multicast out even when the 
> destination mac is wrong?
> Any idea how I could modify (the kernel) so that I could overwrite the 
> faulty mac?
>
> I could not find any description on how to receive dvb-h on the web. 
> The are some mailing on how to find SDP files, but that was not such a 
> big thing (dvbsnoop  -b <pid> ..).
>
>
> Thanks for help,
>
> Dietmar


premitting that I have very little confidence with networking in general...
if you run
$ ifconfig dvb0_0 ip/mask promisc up
$ route add -net 224.0.0.0/4 dev dvb0_0
you shouldn't need to tamper with the MAC addresses.
You can also use smcrouted to re-route the tuple src_ip->dest_ip from 
dvb0_0 to eth0
(although I find it annoying having to know the source ip).
I ad dvb-h working in both manners.
 
 
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