[vlc-devel] Re: Broadcasting/multicasting a DVB transponder signal

Benjamin PRACHT bigben+spam at videolan.org
Fri Dec 31 00:14:39 CET 2004

On Thu, Dec 30, 2004, Marius Kjeldahl wrote :
> I'm grabbing signals from a Twinham DVB card from a satellite feed, and 
> it works mostly ok, except that the linux drivers are a bit unstable 
> (sometimes the frontend driver does not load properly and have to be 
> reloaded and it sometimes have to be rmmod/insmod'ed after use).
> I have verified that I get the signals ok from the card by using 
> commands such as:
> $ ./vlc -vvvv dvb: --program 1501 --dvb-frequency 12322000 --dvb-srate 
> 27800000 --dvb-adapter 0 --dvb-modulation 32 --dvb-voltage 18
> which displays the stream from the dvb card just fine. Next I wanted to 
> take all the channels (or at least a few) from the same transponder and 
> multicast it out on the lan. That is (still) a challenge.
> Searching the mailing lists, I found a series of posts with the subject 
> "multicasting full transponder" or something like that, and I used that 
> to create the following test:
> $ ./vlc -vvvv dvb: --dvb-frequency 12322000 --dvb-srate 27800000 
> --dvb-adapter 0 --dvb-modulation 32 --dvb-voltage 18 --dvb-budget-mode 
> --sout-all --ts-es-id-pid --ts-silent --intf dummy --sout \
> "#duplicate{"\
> "dst=std{access=udp,mux=ts,url=}\",select=\"program=1501\","\
> "dst=std{access=udp,mux=ts,url=}\",select=\"program=1502\""\
> "}
> What I'm trying to do is to take two programs from the same transponder 
> (1501 and 1502 - I have verified they display fine individually) and 
> have vlc send it on the network using udp and with portnumbers matching 
> the program.
> I've tried quite a few "tweaks" to get this working, but have not been 
> successful so far. Do anybody see any obvious mistakes?
> I've also tried replacing access=udp with access=file and a filename in 
> the url to rule out network stuff, but the files get no data either 
> (zero size).
> I am not sure whether the "broadcast all channels in a transponder" is 
> actually supposed to work, but posts I've read from this board in the 
> past indicates that it should.
> In case anybody reads this in the future, the modules that need to be 
> loaded to get the Twinhan DST cards up and running are:
> bttv i2c_hw=1
> dvb-bt8xx
> dst
> Verify that a device like /dev/dvb/adapter0/frontend0 exists after 
> loading the drivers. If it does not, try rmmod and reload the drivers. 
> The frontend device should usually appear after a couple of tries. I'm 
> using devfs and have no idea how to verify that the frontend0 device 
> exists if you are not.

Well, I cannot see any obvious issue in your syntax. Could you send us
the complete log ?

Another possibility could be that your dvb card and/or your drivers
don't have support for the "budget-mode", that allows to grap several
programs at the same time. What kind of card is the Twinham card you are
using ? Does it include a MPEG decoder ? Did you find any info on a way
to enable the budget mode in the drivers ?


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