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

Giovanni giluong at libero.it
Mon Apr 2 10:08:49 CEST 2007


Hi David,
I studied these documents but I have still no idea of how to decode the ESG BiM encoded. In your link there are only DVB-H specification and I'm not a technician of this... Is possible to have anything simpler to understand how to solve my trouble?

Thank you

Giovanni


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

>From      : "david may" david.may10 at ntlworld.com
To          : "Giovanni" giluong at libero.it
Cc          : 
Date      : Sat, 31 Mar 2007 04:49:10 +0100
Subject : Re[3]: [linux-dvb] DVB-H and dvbnet / MAC-broadcast address







Hello Giovanni,

Friday, March 30, 2007, 4:17:20 PM, you wrote:

> 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



> ---------------------------------------------------

> ---------- 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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a silly question but are there no hints in the pdfs here
http://www.dvb-h.org/technology.htm

-- 
Best regards,
 david                            mailto:david.may10 at ntlworld.com




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