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I'm looking for a way to stream audio over the Internet with low latency (preferably less than one second) between one client and one server. Here's the desired setup:

  1. PC at an arbitrary location receives sound input through its sound card
  2. PC broadcasts audio over the Internet to server at central location
  3. Server at central location outputs audio through its sound card. The audio should ideally be output through the server's sound card less than 1 second after it entered the PC.

Currently, we're connecting to IceCast on the server to accomplish this. However, despite a lot of effort we have been unable to bring the latency below 6 seconds, which is too much for our purposes.

Is it possible to set up something purely in software that allows me to get a latency of under one second? If not, is there hardware that can do this? I googled a bit, but found mostly stuff that assumes you're on a LAN (like anything Dante related) or low-quality VoIP stuff.

haroba
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  • Why is the one second latency important? – Michael Hampton Apr 13 '15 at 16:02
  • The setup is for a radio station. Imagine communicating with a remote studio with a delay of 6 seconds. – haroba Apr 13 '15 at 16:05
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    Have you actually measured the end-to-end latency of your path over the internet? – longneck Apr 13 '15 at 16:11
  • The actual network latency between the PC and the server is < 10 ms. I'm pretty sure the audio delay comes from buffering and is pretty much inherent to using IceCast. According to other posts on using IceCast for low-latency applications I'm lucky to even get as low as 6 seconds. – haroba Apr 13 '15 at 16:13
  • You wouldn't do this at all. You would use Icecast to stream to your listeners, since the delay isn't very important there. But you really need a dedicated line (which you seem to have) -- and industry-specific hardware -- to do this right. (One of my clients is a [TALKERS Heavy Hundred](http://www.talkers.com/heavy-hundred/) talk show, so I know a little about this, but I don't have the exact hardware to hand; I handle the Internet side of the show. If you can describe more of the purpose of the setup I can ask, but you may be better served on a radio industry forum.) – Michael Hampton Apr 13 '15 at 16:18
  • You're right, IceCast isn't built for this use, but since we already use it to stream our channel to our listeners that was the first thing we tried. There are two reasons why we want a setup like this. First, and primarily, we want to be able to broadcast entire shows from external locations like bars or concert venues. Second, we want to be able to have reporters at external locations (again, such as a concert venue) and allow them to communicate with our central studio. In other words, we won't have a dedicated line as the reporter/external studio might be anywhere. – haroba Apr 13 '15 at 16:25
  • For the record, this is college radio, which is why the entire setup might just seem a bit unprofessional. ;) – haroba Apr 13 '15 at 16:30
  • And probably no budget either. Well, for remotes we use a portable console from Alesis (who aren't making them anymore unfortunately) and a [portable codec](http://broadcast.bswusa.com/search?view=list&w=portable+codec) (I don't have its info offhand, and it's old anyway) which can dial in via any POTS telephone line. The audio quality is good enough for talk and many people can't distinguish it from in-studio. Some of these codecs can also use the Internet, which is where you want to be looking. (Though we virtually never have reliable Internet at remotes, a POTS line is always available.) – Michael Hampton Apr 13 '15 at 16:35
  • I'm starting to wonder whether the best solution may be using some sort of standard VoIP software and turning the quality setting to its maximum. We often broadcast from random locations on campus where Internet is almost always available, but phone lines are not. However, we do in fact have a somewhat roomy budget, so if there are professional solutions that do exactly what I'm looking for I'd love to hear about them. – haroba Apr 13 '15 at 16:39
  • The linked page gives quite a few Internet-capable codecs, so I'd go shopping :) – Michael Hampton Apr 13 '15 at 16:41

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