Windows 8 low latency video streaming

 

My game is based on Flash and uses RTMP to deliver live video to players. Video should be streamed from single location to many clients, not between clients. It's essential requirement that end-to-end video stream should have very low latency, less than 0.5s.

Using many tweaks on server and client, I was able to achieve approx. 0.2s latency with RTMP and Adobe Live Media Encoder in case of loopback network interface.

Now the problem is to port the project to Windows 8 store app. Natively Windows 8 offers smooth streaming extensions for IIS + http://playerframework.codeplex.com/ for player + video encoder compatible with live smooth streaming. As of encoder, now I tested only Microsoft Expression Encoder 4 that supports live smooth streaming. Despite using msRealTime property on player side, the latency is huge and I was unable to make it less than 6-10 seconds by tweaking the encoder. Different sources state that smooth [live] streaming is not a choice for low-latency video streaming scenarios, and it seems that with Expression Encoder 4 it's impossible to achieve low latency with any combination of settings. There are hardware video encoders which support smooth streaming, like ones from envivio or digital rapids, however:

  • They are expensive
  • I'm not sure at all if they can significantly improve latency on encoder side, compared to Expression Encoder
  • Even if they can eliminate encoder's time, can the rest of smooth streaming (IIS side) support required speed.

    • Questions:

  • What technology could be used to stream to Win8 clients with subsecond latency, if any?
  • Do you know players compatible with win8 or easily portable to win8 which support rtmp?

    • Addition. Live translation of Build 2012 uses Rtmp and Smooth Streaming in Desktop mode. In Metro mode, it uses RTMP and Flash Player for Metro.

    I can confirm that Smooth Streaming will not be your technology of choice here. Under the very best scenario with perfect conditions, the best you're going to get is a few seconds (absolute minimum latency would be the chunk length itself, even if everything else had 0 latency.)

    I think most likely RTSP/RTMP or something similar using UDP is your best bet. I would be looking at Video Conferencing technologies more than wide audience streaming technologies. If I remember correctly there are a few .NET components out there to handle RTSP H.264 meant for video conferencing - if I can find them later I will post here.

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