[clug] wireless audio and video

Robert Edwards bob at cs.anu.edu.au
Wed Sep 26 03:26:55 GMT 2007

I think the main issue here is whether you want/need to have the same
material playing at different stations at the same time (ie. "in sync").

Analogue A/V senders solve this, but it is hard to get more than a
couple of simultaneous signals going (and to keep your neighbours out).

Otherwise, multicasting is the correct solution, but not so well
supported in the FOSS world still. More importantly, a wireless Access
Point (WAP) should be multicast aware, automatically propagating multi-
cast channels that wireless clients are actually wanting to receive,
and ceasing to propagate any channels that are no longer required. The
protocols for doing all this exist, but I am not aware of many home or
small office (ie. low-cost) WAPs that implement them.

802.11g, working optimally at 54Mbps (which it rarely does) should, in
theory, be capable of carrying several (up to about six) standard
resolution (digital-TV-quality) channels over multicast (ie. no
acknowledgements required from the receiving stations). 802.11b, again
working optimally at 11Mbps, should be able to carry one multicast
video stream and a couple of multicast 128kbps MP3 or Ogg audio

As for actual kit that will do all this - it might be a question of
roll your own as far as the WAP is concerned and low-cost receiving
stations are generally set up for uPnP, which is not-multicast aware.

But the dream is there (I have it too), so we should be able to do
something eventually to make all this work.


Bob Edwards.

David Tulloh wrote:
> Kim Holburn wrote:
>> I have this dream of having some kind of wireless system that will let 
>> me put at least speakers in different rooms and maybe even screens as 
>> well and route audio from one or more sources to one or more sets of 
>> speakers and possibly the same with video.
>> I'd of course prefer all linux but it wold be essential to integrate 
>> at least one linux server and of course I really wouldn't want to have 
>> to run a windows server at all.
>> Does anyone have any ideas about such a thing?
> I've put some thought into such a thing, there are products that try to 
> meet this market but none of the product I've looked at seemed very good 
> and they are all on the hideously expensive end of the scale.  I have a 
> few ideas on building something like this but I don't have any pressing 
> need for it at the moment.
> Wireless video is still not commonly not done due to bandwidth required.
> Something like the AudioControl set of products let you run sound and 
> video over RJ45 cable, handy if you have that in your house already.
> http://www.wholehouseaudiocontrol.com/product.asp?Product_Id=252633
> David

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