[streaming] Re: Reliable streaming format for wireless links

[Marshall Eubanks]

You need FEC (forward error correction). How you can get it in VLC is  
another question;
now that 3GPP MBMS and 3GPP2 BCMCS have adopted the Raptor FEC, maybe  
VLC
should support it too.

Regards
Marshall

On Mar 13, 2006, at 10:10 AM, Romuald CARI wrote:

> Niall Donegan a écrit :
>
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>> I'm setting up a server to stream the input from a Hauppauge PVR-150
>> card and it works very nicely here over the wired network. The  
>> command
>> I've using for vlc is:
>>
>> vlc pvr:/dev/video0:norm=pal:size=720x576 -I telnet --sout udp: 
>> 239.0.0.1
>> - --ttl 1
>>
>> which pipes the mpeg2 output straight over vlc.
>>
>> The problem is that when I start to use a wireless link (2x Linksys
>> WAP54G in bridge mode) there is random errors showing up in the video
>> stream.
>>
>> I know the problem is that udp doesn't garrentee packets will get  
>> there
>> which hasn't been a problem on the wired network, but what method or
>> protocol would be more appropriate for multicasting over wireless?
>>
>> Thanks.
>>
>>
>> - --
>> Niall Donegan
>> niall\at\moybella\dot\net
>> Public-Key: http://moybella.net/~niall/public.gpg
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> UDP + Wireless create creepy things.
> The problem is that in UDP broadcast / multicast, packets are send  
> once for all with no transmission check. Wireless protocols can not  
> guarantee that all UDP datagrams will be transmitted properly. The  
> only way to get a "secure" transmission over wireless links, I  
> think, is to establish a TCP connection, using HTTP protocol for  
> example, and to set a huge buffer time on the client side (10  
> seconds maybe). The HTTP protocol, because it uses TCP will handle  
> the errors and resend the data as much as necessary, so you should  
> not see those creepy things in your image. You can not create  
> "secure" multicasting over wireless networks, there is no way to  
> guarantee that yout clients will get all the data.
>
> You could try to reduce the stream bandwidth and create unicast TCP  
> connections to your clients using HTTP, good luck !
>
> Romuald
>
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