Large delays (2 minute) with dummynet

From: josh (joshua_at_fuckmicrosoft.com)
Date: 07/16/04

  • Next message: Lev Walkin: "Re: Large delays (2 minute) with dummynet" 
    Date: Fri, 16 Jul 2004 10:09:35 +1000
To: freebsd-net@freebsd.org

    I hope this is the right list to post to.

    I'd like to delay a shoutcast stream by around 2 minutes. This
    shoutcast server is used to broadcast commentary on live games and
    the delay is needed so teams can't gain an advantage by hearing the
    commentary to learn where/what the other team is doing. I've
    checked the shoutcast forums and it seems there's nothing I can do
    to the shoutcast daemon to get this delay. Shoutcast listens on
    tcp/8001 for an input stream, and tcp/8000 for listeners to connect
    to.

    With 100 streams each using 48kbps, how practical is it to put them
    all through a dummynet pipe with a delay of 120000ms? I figure
    that'll require 100 * 48 / 8 * 120 / 1024 = 70MB of buffering in
    dummynet. That's heaps! Is that possible? Is that using mbufs?
    What would have to be tweaked up?

    I guess it'd be better if I could just add the 2mins of delay to
    the input stream so the delay buffer is smaller and fixed, but I
    don't know how the shoutcast protocol would like that or how the
    different TCP implementations would like it. Would ACKs be coming
    back to the shoutcaster 2 minutes late?

    Ideally it'd be best to have all this buffering happen intelligently
    in userland, but I can't find anything to do that. Am I barking up
    the wrong tree by looking at dummynet?

    Cheers,
          Josh
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  • Next message: Lev Walkin: "Re: Large delays (2 minute) with dummynet"