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c#nancyhttpservermjpeg

How can I write an MJPEG server using Nancy?


I have the following:

public sealed class ServerModule : NancyModule
{
    public ServerModule()
    {
        Get["/video"] = o =>
        {
            byte[] img = GetImage("whatever.jpeg");

            return new MjpegResponse(firstImg);
        };
    }

    private sealed class MjpegResponse : Response
    {
        public MjpegResponse(byte[] data)
        {
            this.Headers.Clear();
            this.Headers.Add("Server", "IP Webcam Server 1.5");
            this.Headers.Add("Connection", "close");
            this.Headers.Add("Cache-Control", "no-store, no-cache, must-revalidate, pre-check=0, post-check=0, max-age=0");
            this.Headers.Add("Pragma", "no-cache");
            this.Headers.Add("Expires", "-1");
            this.Headers.Add("Access-Control-Allow-Origin", "*");

            this.ContentType = "multipart/x-mixed-replace;boundary=Ba4oTvQMY8ew04N8dcnM";

            var footer = Encoding.ASCII.GetBytes("\r\n");
            this.Contents = stream =>
            {
                using(var writer = new BinaryWriter(stream))
                {
                  writer.Write(data);
                  writer.Write(footer);
                }
            };
        }
    }
}

The headers match the headers that I am getting from an IPCamera which has a built-in MJPEG server even though Fiddler is showing the correct headers:

HTTP/1.1 200 OK
Cache-Control: no-store, no-cache, must-revalidate, pre-check=0, post-check=0, max-age=0
Pragma: no-cache
Transfer-Encoding: chunked
Content-Type: multipart/x-mixed-replace;boundary=Ba4oTvQMY8ew04N8dcnM
Expires: -1
Server: IP Webcam Server 1.5 Microsoft-HTTPAPI/2.0
Access-Control-Allow-Origin: *
Date: Tue, 24 Nov 2015 21:23:29 GMT
Connection: close

When trying in an MJPEG enabled browser (Firefox) it is unable to stream or show anything. Another thing I have noticed is the Transfer-Encoding: chunked which should not be appearing.

Any ideas?


Solution

  • I think the issue here is quite simple to resolve. After writing to a stream, it point to the end of it. You need to rewind that pointer to the start of the stream before returning with a response:

       stream.Seek(0, SeekOrigin.Begin);