Re: Broadcast Protocols
Re: Broadcast Protocols
- Subject: Re: Broadcast Protocols
- From: Gordon Apple <email@hidden>
- Date: Fri, 21 Sep 2012 22:07:17 -0500
- Thread-topic: Broadcast Protocols
Title: Re: Broadcast Protocols
On 9/21/12 4:09 PM, "Jens Alfke" <email@hidden> wrote:
“Um, how did we confirm that? What we said is that for true multicast you need to use UDP, and that multicast packets are more expensive than regular packets.
Two possibilities:
(1) Use multicast, send UDP packets, and verify that you’re not sending at a high enough rate that it causes problems.
(2) Advertise your service over Bonjour, then open individual TCP streams to every client that connects.”
Well, I gathered that it wasn’t going to be easy. I was hoping for a simple solution, like just connect to a WiFi router and let it handle it. But, again, WiFi capacity will choke on the number of connections at some point if you have individual streams. If we use TCP, one weak receiver could further choke the throughput. Might work for a demo or small group. Whatever we do, it should involve only software in the source computer, plus a (hopefully) inexpensive WiFi router and video display in the receivers (laptops or iDevices).
I’m going to have to find out how much built-in support we have for doing UDP multicast. Last time I asked here about UDP, I was basically told to forget it, that everything was going to be TCP.
“That sounds like kind of a big feature to add right before beta, in my opinion. Networking is hard, and real-time is hard.”
This is one of those projects that will probably never be “finished”, although at some point it has to be frozen and put out there. I’ve been lobbying for including streaming video components in AVFoundation. Although our primary output will be HD video of the presentation screen, we also want to include other data.
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