[AG-DEV] Tapping into the video streams

[Andrew Rowley]

Hi,

I have discovered what the problem is.  There is a bug in Java for linux which is caused by IPv6 being enabled.  You can tell java to use IPv4 instead by calling -Djava.net.preferIPv4Stack=true on the java command line.

Also, I have found that vic on linux disables the loopback of multicast packets (using the IP_MULTICAST_LOOP socket option).  Unfortunatly, on linux, this appears to disable the looping of *outgoing* packets rather than incoming packets (on windows, the opposite happens, so the socket that requests the disabling of the loop doesn't receive packets sent by the local host, which makes more sense in my mind).  So any packets sent out by vic will not be looped back to the local machine.  You can resolve this by downloading the vic source and recompiling with this disabled.  The offending lines are in vic/net/net-ip.cpp - on line 482 change c = 0 to c = 1.

Note also that rat doesn't appear to have loopback disabled so it works fine.

Andrew :)

=============================
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-----Original Message-----
From: owner-ag-dev at mcs.anl.gov [mailto:owner-ag-dev at mcs.anl.gov] On Behalf Of lester leong
Sent: 12 November 2007 07:15
To: Andrew.Rowley at manchester.ac.uk
Cc: ag-dev at mcs.anl.gov
Subject: Re: [AG-DEV] Tapping into the video streams

Hi Andrew,

Thats right, I am running on Linux :-)

Cheers
lest

On Nov 9, 2007 9:13 PM, Andrew Rowley <Andrew.Rowley at manchester.ac.uk> wrote:
> Hi,
>
> Funny you should mention this - we seem to be having difficulty with receiving multicast locally on multicast sockets when using Java in linux.  Is this the O/S you are using, or are you using windows?  If windows, it should work.  You may need to call socket.setLoopbackMode(false) to allow packets to loop back locally.
>
> If this is on linux, there may be a bug...
>
> Andrew :)
>
> =============================
> Research Computing Services,
> Manchester Computing,
> Kilburn Building,
> University of Manchester,
> Oxford Road,
> Manchester,
> M13 9PL,
> UK
> Tel: +44(0)161-275 0685
> Email: Andrew.Rowley at manchester.ac.uk
>
>
>
> -----Original Message-----
> From: owner-ag-dev at mcs.anl.gov [mailto:owner-ag-dev at mcs.anl.gov] On Behalf Of lester leong
> Sent: 09 November 2007 12:55
> To: ag-dev at mcs.anl.gov
> Subject: [AG-DEV] Tapping into the video streams
>
> Greetings,
>
> I am new to AG and have been trying to see if I can tap into the rtp
> multicast session using my exising standalone viewer implemented with
> JMF (lets call it myViewer).
>
> If I run AG's VideoProducerService on machineA and use myViewer on
> machineB (with the multicast ip/port), I will be able to view the
> captured feeds on machineB. However, if run everything in one single
> machine, I will fail to receive any video feeds on myViewer. Any idea
> what could be blocking me from receiving my own feeds?
>
>
> Thanks in advance.
>
>
>



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