[maemo-developers] How to setup multicast over wifi, 3G, DVB-H ? (pls don't delete - r&d project)

From: Darius Jack dariusjack2006 at yahoo.ie
Date: Tue Nov 6 21:33:59 EET 2007
Thanks Aleksandr for your kind explanation to me.
>From Google I get the like idea - called Wifi Radio
Exactly what I mean but broadcasted locally by local WiFi AP to local wifi clients only.
WiFi Radar 

wifi enabled portabled media player


another media streamer and wifi radio


Last September, Toronto became one of the first major cities where a major radio broadcaster launched a new radio format available not over the old airwaves...but through the Internet to be heard on the new free city WiFi services.

another wifi player
Zing Wi-Fi Radio/MP3 Playerhttp://images.google.com/imgres?imgurl=http://www.ubergizmo.com/photos/2006/6/zing-wi-fi-mp3-player.jpg&imgrefurl=http://www.ubergizmo.com/15/archives/2006/06/zing_wifi_radiomp3_player.html&h=316&w=200&sz=11&hl=en&start=11&sig2=QnpIxp-i0usKDAawJUyYEg&um=1&tbnid=BsqJIcCwOCJ2eM:&tbnh=117&tbnw=74&ei=8bgwR7auNpSS-gKl_9XBBQ&prev=/images%3Fq%3Dwifi%2Bradio%26svnum%3D100%26um%3D1%26hl%3Den%26sa%3DN
more and more and nothing of the kind I mean, i.e.
multicasting, open packet reading vs. server streaming peer-to-peer.

I have already tested TVersity media server in ad-hoc configuration.
Tversity server is streaming and Media Streamer installed on maemo can listen to streams and play audio/video live.
What I need now is to have another wifi-enabled radio/media player to receive
media stream packets and play from a bufor.

So I want second and subsequent clients to read and bufor media stream packets already wifi broadcasted by established ad-hoc wifi network only,
acting as fm not wifi radio, the latter connecting to a server streaming media
to play any stream.
As local channel should be public/open, application like kismet or other packet sniffers can already read, bufor and regenerate media packet streaming
to be played by client's media streamer.

What I need is to know how to remove middle-ware and how selecting multicast broadcasting can help establish open media broadcasting ovr wifi.


Aleksandr Koltsoff <czr at iki.fi> wrote: Hello Darius (and others),

Darius Jack wrote:
> But what I need to establish is open multicast - broadcasting channel for media (TVersity or another streaming back end servwer).
> In ethernet configuration multicast packets from multicat IP range are copied by a router and sent to each respective IP address assigned by DHCP server running at multicast router .

Multicast in ethernet actually works slightly differently. There is a
mapping from the IP-group addresses ("class d") into specific Ethernet
MACs (which have the broadcast bit set, but not all bits are set to
ones, as in broadcast). Stations on the same segment will then filter
those packets which they deem "useful" (based on programs binding for
multicast IP addresses for reception). Routing multicast IP traffic is
an different issue, as is multicast filtering (both require a working
IGMP setup and multicast routing also requires some higher level
multicast routing protocol like PIM). DHCP is not involved (other than
when used as MADCAP server, which is not common in UNIX/Linux world).
IPv6 changes these things slightly as well.

> Multicast over wifi should be configured as an open stream channel like DVB-H/G3 to provide open listen to, access to any device switched to listen to mode , like fm radio , sat tv or the like.

"Wi-Fi" (802.11a/b/g) works as a transparent "ethernet" service. So in
fact, multicasting IP traffic in a wireless 802.11 environment isn't any
different from multicasting in ethernet. A problem which people often
will run with multicast in wireless is encryption (WEP/WPA/CCMP) and
bad/flakey support of access points to do use correct keys for broadcast
and multicast traffic. A lot of the cheaper APs have serious problems
with proper key usage anyway unless one uses shared key WEP. However, in
your case I think it wouldn't be a problem as you seem to want to run a
"public/open" wireless setup.

> So please let me know how to setup media streamer client's application to ignore IPs in packets streamed by server and have to read selected open channel wifi stream , bufor and read in media streamer application.

Not really sure what you're after here. You might start testing your
setup by running the video lan client (vlc) (for streaming and testing
multicast) first, and when your wireless setup seems to work with normal
Linux boxes over wireless, you'll want to find a media client/player for
the Internet Tablets which is capable of receiving unreliable/multicast
streams and start hacking on that (a topic where other people surely can


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