SharpRTSP to WebRTC

This is a proof of concept bridge in between RTSP and WebRTC implemented in C#. It can take any H264/H265 RTSP stream and feed it through WebRTC to the web browser. It does not perform any video transcoding which makes it lightweight and portable. It does support audio transcoding from AAC to Opus, all implemented in netstandard and NET8 without any native dependencies.

What can it do?

• Re-stream H264/H265 RTSP from any source to the web browser
• Stream aggregation - there is only a single session in between the gateway and the RTSP source, no matter how many users are watching the stream
• Transcode AAC audio to Opus with a small latency in audio

Compatibility

Because no video transcoding is being performed, the web browsers must support decoding of the source video codecs in WebRTC.

H264

This should be supported by the majority of web browsers as it is among the codecs required by WebRTC. There might be an exception for Firefox on Android according to this: https://developer.mozilla.org/en-US/docs/Web/Media/Formats/WebRTC_codecs.

H265

Although most of the web browsers today support H265 video decoding, it does not mean H265 will also work in WebRTC. As of April 2025, H265 in WebRTC is supported in the latest releases of Safari. It is also supported in Chrome Canary 136+.

Samples

RTSPtoWebRTCGateway

There is a sample ASP.NET Core app that demonstrates the functionality on multiple live streams. To change the default configuration, just modify the appsettings.json:

"Cameras": [
    {
      "Name": "name1",
      "Url": "rtsp://url1",
      "UserName": "MyUserName",
      "Password": "MyPassword"
    },
    {
      "Name": "name2",
      "Url": "rtsp://url2",
      "UserName": null,
      "Password": null
    }
  ]

Minimal example

In Startup.cs, add the following piece of code to register the RTSPtoWebRTCProxyService:

builder.Services.AddSingleton<RTSPtoWebRTCProxyService>();

Then (optionally) add the configuration of streams from appsettings.json:

builder.Services.Configure<List<CameraConfiguration>>(builder.Configuration.GetSection("Cameras"));

Implement a minimal WebRTC signalling controller, for instance:

[ApiController]
[Route("api/[controller]")]
public class WebRTCController : ControllerBase
{
    private readonly IList<CameraConfiguration> _cameras;
    private readonly RTSPtoWebRTCProxyService _webRTCServer;

    public WebRTCController(IOptions<List<CameraConfiguration>> cameras, RTSPtoWebRTCProxyService webRTCServer)
    {
        _cameras = cameras.Value;
        _webRTCServer = webRTCServer;
    }

    [HttpGet]
    [Route("getcameras")]
    public IActionResult GetCameras()
    {
        return Ok(_cameras.Select(x => x.Name).ToList());
    }

    [HttpGet]
    [Route("getoffer")]
    public async Task<IActionResult> GetOffer(string id, string name)
    {
        return Ok(await _webRTCServer.GetOfferAsync(id, camera.Url, camera.UserName, camera.Password, camera.StartPort, camera.EndPort));
    }

    [HttpPost]
    [Route("setanswer")]
    public IActionResult SetAnswer(string id, [FromBody] RTCSessionDescriptionInit answer)
    {
        _webRTCServer.SetAnswer(id, answer);
        return Ok();
    }

    [HttpPost]
    [Route("addicecandidate")]
    public IActionResult AddIceCandidate(string id, [FromBody] RTCIceCandidateInit iceCandidate)
    {
        _webRTCServer.AddIceCandidate(id, iceCandidate);
        return Ok();
    }
}

Finally, for the WebRTC viewer you can refer to src/rtsptowebrtc.client/src/CameraViewer.jsx.

Hosting on a public IP address

It is recommended to use a TURN server such as https://github.com/coturn/coturn when hosting this project on the Internet. To host this project on a public IP address without using a TURN server, you will have to configure port ranges (StartPort, EndPort) for each camera in appsettings.json. Then you have to configure port forwarding of all the ports in the configured port ranges to this server + port forwarding for the web application. In some cases, you might also want to configure your server public IP address to be included in the ICE candidates. You can use PublicIPv4 and PublicIPv6 in appsettings.json for this purpose.

Credits

• sipsorcery - WebRTC implementation in netstandard which has made this project possible https://github.com/sipsorcery-org/sipsorcery
• SharpRTSP - RTSP client https://github.com/ngraziano/SharpRTSP
• concentus - Opus codec implementation https://github.com/lostromb/concentus