Low latency streaming with multiple clients

Completed

Permanently deleted user

July 13, 2021 20:49

We are trying to figure out how to fit Nx Witness into our system, and have been told this is the best place to ask.

We have a system where the real-time camera stream (a few seconds latency) for multiple cameras could be viewed at any time from multiple web browser/client locations. A conservative estimate is that any camera stream could be viewed by 20+ client browsers at any given time.

The default settings for the HLS stream has a significant amount of latency, and the webm transcoding appears limited in connection count. Given the requirements, what is the best method for real-time streaming using the Nx Witness? Could some issues be mitigated through certain hardware specs?

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  Anton Babinov

  • Network Optix team

  July 14, 2021 11:23 Edited

  Hello Andrew,

  We have a system where the real-time camera stream (a few seconds latency) for multiple cameras could be viewed at any time from multiple web browser/client locations. A conservative estimate is that any camera stream could be viewed by 20+ client browsers at any given time.

  What about the location of the client browsers? Are they going to be connected locally or over the internet? What are the requirements for video quality? 

  The default settings for the HLS stream has a significant amount of latency, and the webm transcoding appears limited in connection count.

  HLS is efficient for saving bandwidth, but significant delay is part of its design. I'd recommend using HTTP progressive streaming if you want minimum delay. Check HTTP Streaming section in our API reference.

  webm transcoding limit can be increased via advanced settings in web admin interface. There is also possibility to request stream "as is" without the transcoding. Main purpose of the transcoding is to downscale the stream to save internet bandwidth. In addition, transcoding is required when video encoding profile from camera isn't supported by web-browser, but this can be solved by changed video codec parameters in camera or VMS.

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  Permanently deleted user

  July 14, 2021 18:21

  Hi Anton, thanks for the quick reply.

  What about the location of the client browsers? Are they going to be connected locally or over the internet? What are the requirements for video quality? 

  All client browsers will be within a local network, no access from the internet. For the live stream, the video quality will max out at 1280x720, 15 FPS, using H264 encoding. This is what is sent out through the cameras RTSP streams into Nx Witness.

  There is also possibility to request stream "as is" without the transcoding

  Is this done using the same HTTP Streaming API?

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  Anton Babinov

  • Network Optix team

  July 15, 2021 06:50

  All client browsers will be within a local network, no access from the internet. For the live stream, the video quality will max out at 1280x720, 15 FPS, using H264 encoding. This is what is sent out through the cameras RTSP streams into Nx Witness.

  In that case you should be fine without video transcoding.

  Is this done using the same HTTP Streaming API?

  Yes, you can request video with requests like:

  /media/<cameraId>.mkv
  /media/<cameraId>.mp4

  This way transcoding won't be performed.

   

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