How do I stream video from iPhone acting as a server?

Question

I\'m working on an app for iOS, where one iPhone has to live stream its camera recordings to another iPhone (to keep things simple, both are in the same Wi-Fi network).

Answer 1

1. Sounds OK?

2. Video frames are really big. You're going to have bandwidth problems streaming video from one device to another. You can compress the frames as JPEGs using UIImageJPEGRepresentation from a UIImage, but that's computationally expensive on the "server", and still may not make them small enough to stream well. You can also reduce your frame rate and/or resolution by dropping frames, downsampling the UIImages, and fiddling with the settings in your AVCaptureSession. Alternately, you can send small (5-second) videos, which are hardware-compressed on the server and much easier to handle in bandwidth, but will of course give you a 5-second lag in your stream.

3. If you can require iOS 7, I'd suggest trying MultipeerConnectivity.framework. It's not terribly difficult to set up, and I believe it supports multiple clients. Definitely use UDP rather than TCP if you're going to roll your own networking - this is a textbook application for UDP, and it has lower overhead.

4. Frame by frame, just turn the JPEGs into UIImages and use UIImageView. There's significant computation involved, but I believe you'll still be limited by bandwidth rather than CPU. If you're sending little videos, you can use MPMoviePlayerController. There will probably be little glitches between each video as it "prepares" them for playback, which will also result in requiring 5.5 seconds or so to play each 5-second video. I wouldn't recommend using HTTP Live Streaming unless you can get a real server into the mix somewhere. Or you could use an ffmpeg pipeline -- feed videos in and pop individual frames out -- if you can/want to compile ffmpeg for iOS.

Let me know if you need clarification on any of these points. It's a lot of work but relatively straightforward.

Answer 2

If you need a solution off the shelf, you may try some ready streaming libraries. The one I have experience is angl streaming lib. Works pretty well with RTMP output to Wowza media server.