Channel service tools are useful when you want to stream multiple videos at the same time and enable the clients to change channel (i.e. switching from one stream to another) easily without typing IP addresses, but just using the interface and selecting a channel number.
The channel service tool that you will use depends on your network :
mini VideoLAN
Channel Server (miniVLCS)
;
VLAN server
(either the VLAN Server or the mini VLAN
Server), and if your router cannot filter between VLANs, you will use a
VLAN bridge
in order for the clients to be able to communicate
with all the other machines when watching a stream.
miniVLCS
, but this is so dirty that you shouldn't even think about it !
Warning : the network tools that will be presented in this section have been tested only under Linux. We cannot guarantee they will work with other operating systems.
If your network supports multicast, you will use the mini VideoLAN
Channel Server (miniVLCS)
as your channel tool. This program sends
the parameters the VideoLan Clients need in order to receive the
streams.
Download the file miniVLCS-0.1.2.tar.gz
from the
Network download page.
Then uncompress the archive and build the program :
% tar xvzf miniVLCS-0.1.2.tar.gz
% cd miniVLCS-0.1.2
% make
It creates an executable program named vlcs
.
Edit the configuration file vlcs.conf
.
The first line corresponds to channel 0, the second line corresponds to channel 1, the third line to channel 2, and so on.
In each line, put what you would type on the command line of vlc
,
except for the first line I: nostream
. It means that you don't
stream anything in channel 0.
For example, if you have two multicast stream :
vlcs.conf
file would be :
I: nostream
udp:@239.255.12.42
udp:@239.255.12.43
As normal user, do :
% ./vlcs
You must restart vlcs every time you change the configuration file
vlcs.conf
.
vlc
configuration
The simplest solution is to use the interface of vlc : click on "Net", select "Channel server", write its IP address or DNS name.
Then, you see a new section "Network Channel" on the interface.
Select the desired channel and click on Go!
.
If your network doesn't support multicast but supports VLANs, you will use a VLAN server. If your network supports multicast, you will certainly NOT want to use this solution, because it is far more complex to set up and far more dangerous for the stability of your network. The VLAN solution has been tested on "our" previous network (the network of the student residence of the Ecole Centrale Paris) and worked well. But we now have a new network which supports multicast, so the VLAN solution is not tested nor developed any longer.
In order to explain the VLAN solution, I will take the example of our previous network. This network had :
As an MPEG stream needs a bandwith between 4 to 9 Mbit/s, we could send multiple streams on our 155 Mbit/s backbone, but each student had a 10 Mbit/s connection and therefore could only receive one stream at the same time. It was out of the question to send the stream to machines that didn't want to receive it.
So the idea was to broadcast each stream in a VLAN, different from the regular VLAN. In order for a student to change channel, we needed to change his machine of VLAN. This was the job of the VLAN Server. The VLAN Server received the requests of the VideoLAN Clients and changed the machines of VLAN by sending SNMP requests to the switches.
We had the following VLAN configuration :
The VLAN Server has a big database with the correspondence between the MAC addresses of the clients Ethernet network cards and the couple (switch, port) where the client machine is connected. The VLAN Server can fill up his database and update-it automatically by sending regularly SNMP requests to the switches.
Let's take the following scenario as an example :
vlc
on its
machine and select channel 1. When he clicks on "Go!", his computer
sends a request to the VLAN Server. This requests contains the MAC
address of his Ethernet card and the number of the channel that he wants
to watch.
vlc
displays it.
vlc
, his machine sends another request to
the VLAN Server asking to be put back to the regular VLAN (i.e. VLAN 2).
The VLAN Server receives the request and put the port back to VLAN 2.
There is another problem : we want the machines in VLAN 3, 4 and 5
to be able to communicate with all the other machines. If you have a
good router, you can configure it so as to let the different VLANs
communicate but without letting the streams broadcasted by vls
in a VLAN
go to the other VLANs. But if you have a bad router like our old router,
you need to develop another solution, called VLANbridge. The idea of the
VLANbridge is to have a machine under Linux connected to all the VLANs.
This machine is configured so as to let the different VLANs communicate,
but it prevents the streams broadcasted by vls
in a VLAN go to the other
VLANs.
First, the VideoLAN team developed a VLAN Server and a VLANbridge in C language. When a computer asked to go to channel 1, it sent a request to the VLANserver. The VLANserver received this request, put the port of the switch on which the computer was connecter in VLAN 3, and transmitted this information to the VLANbridge so that the computer was "bridged" with the other VLANs. The advantage of this solution was that the computer hosting the VLAN Server could be a pretty modest machine. But the VLAN Server was quite complex (all his database was written from scratch in C language !), it segfaulted too often, there was regularly MAC addresses missinig in its database, and there was sometimes some problem of communicaction with the VLANbridge.
Then, in year 2001, the VideoLAN team started to develop a new set of tools for the VLAN solution.
Marc Ariberti and Boris DorХs developped a new VLANbridge, called
vlb-linux
. The idea was that the VLANbridge sould learn the
changes by itself, and didn't need to communicate with the VLAN Server.
They developed a patch for the bridge module of the Linux kernel, so as
to serve the needs of VideoLAN. You just have to tell to the VLANbridge
the MAC addresses of the vls
, and it automatically learn which machine
is in which VLAN, and enable the VLANs to communicate but it firewalls
the packets that have the source MAC address of a vls
.
Marc Ariberti and Christophe Massiot developed a new VLAN Server, called
mini VLAN Server
. The idea was to use a PostgreSQL database
instead of the "hand-made" database of the VLAN Server. The mini VLAN
Server is written in PHP (for the heart and all the requests to the SQL
database) and C (for the reception of the requests from the VideoLAN
Clients). It is more reliable, it never segfault, but it needs a decent
machine (we used a 300Mhz Pentium with 128Mo de RAM for a network
of 1000 machines). The mini VLAN Server cannot be used with the old
VLANbridge.
Eventually, if your network doesn't support multicast, we advise you
to use the mini VLAN Server
. And if you router cannot make
the VLANs communicate with filtering functions (in order to stop the
streams broadcasted to go from a VLAN to another), we advise you to use
vlb-linux
.
The installation of the mini VLAN Server
is not explained
here because it is quite complex and we think that most of you have a
network with multicast support. You can download it from the
Network download page. The "tarball" contains an "INSTALL" file with
instructions in French. If you want to use the mini VLAN Server and
don't understand French, you can ask for help in the mailing-list
vlcs@videolan.org
.
You can download this version of the VLANbridge from the Network download page. The "tarball" contains an file "vlanbridge-help" with detailled explainations in English of the idea behind the VLANbridge and, at the end, the instructions to install and configure this version of the VLANbridge.
vlc
configuration
The simplest solution is to use the interface of vlc : click on "Net", select "Channel server", write its IP address or DNS name.
Then, you see a new section "Network Channel" on the interface.
Select the desired channel and click on Go!
.
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