HLS(HttpLiveStreaming) vs RTP(Real-time Transport Protocol) on UDP for mobile P2P?

I'm testing Audio/Video P2P connection between mobile devices.

Studying WebRTC, I've noticed NAT traversal(uses STUN server) and UDP-hole-punching is the key to make P2P possible.

On the other hand, I've noticed HLS(HttpLiveStreaming) on iOS devices is very optimized for A/V live streaming, and widely available even with Android4.x(3.x unstable)

So, here is my question if I use HLS for mobile P2P:

a) HLS is a protocol on TCP(HTTP) not UDP, so isn't there a performance drawback?

See: TCP vs UDP on video stream

b) How about NAT traversal? Will it be easier since HLS is HTTP(port:80)? I have read wikipedia http://en.wikipedia.org/wiki/HTTP_Live_Streaming

Since its requests use only standard HTTP transactions, HTTP Live Streaming is capable of traversing any firewall or proxy server that lets through standard HTTP traffic, unlike UDP-based protocols such as RTP. This also allows content to be delivered over widely available CDNs.

c) How about android device compatibility? Is there a lot of problems to invoke StreamingLive distribution?



The reason why firewalls are not an issue for HLS is that it's a client-server protocol where all requests are done via HTTP on port 80. If you are implementing a P2P application, you won't be able to attach it to a port below 1024 unless you have root privileges.

This means that exchanging data via HLS (port 80) won't work for P2P. Unless you have a translation server in the middle, which defeats the purpose of P2P.

Comparing HTTP Live Streaming to P2P video streaming over UDP/RTP is almost like comparing apples and oranges. More like oranges and tangerines... read on.

HTTP Live Streaming was designed as client-server protocol without P2P or NAT traversal consideration. The idea being that the streaming server is already over HTTP/TCP and accessible from the public internet as if it was just an ordinary web server. The key features of HLS is its ability to dynamically switch the bitrate based on how well the client receives the stream. If the client connection to the server hiccups trying to stream down a 1080p video, it can transparently switch to sending a lower bitrate video (and likely switch back to streaming at higher bitrate if network conditions improve). Good example: Netflix.

WebRTC and ICE were designed to stream real time video bidirectionally between devices that might both behind NATs. As such, traversing a NAT through UDP is much easier than TCP. UDP lends itself to real-time (less latency) than TCP. Most video-chat clients (ala Skype) have dynamic bandwidth adjustments built in to their codecs and protocols to achieve something similar to what HLS does.

I suppose you could combine TCP NAT traveral and HLS together. Doing HLS over UDP implies that you build a TCP like reliability layer on top of your UDP stream.

Hope this helps


HTTP Live Streaming

The new trend in streaming is the use of HTTP with protocols that support adaptive bitrates. This is theoretically a bad fit, as HTTP with TCP/IP is designed for reliable delivery rather than keeping up a steady flow, but with the prevalence of high-speed connections these days it doesn't matter so much. Apple's entry is HTTP Live Streaming, aka HLS or Cupertino streaming. It was developed by Apple for iOS and isn't widely supported outside of Apple's products. Long Tail Video provides a testing page to determine whether a browser supports HLS. Its specification is available as an Internet Draft. The draft contains proprietary material, and publishing derivative works is prohibited.

The only playlist format allowed is M3U Extended (.m3u or .m3u8), but the format of the streams is restricted only by the implementation.

I could achieve P2P on top of HLS using WebRTC on a Android with a Mozilla Firefox browser and two others desktop browsers (Chrome and Firefox) on the same swarm.

Here's a screenshot of a presentation that I've made on the University: https://www.dropbox.com/s/zyfgs4o8al9ovd0/Screenshot%202014-07-17%2019.58.15.png

This screenshot was made by acessing http://bem.tv/demo.html.

If you want to know more about, this is my masters project and I'm publishing my advances on http://bem.tv and http://github.com/bemtv.

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