Web API 从缓冲区流式传输图像

Question

出于某种原因，我无法使下面的代码正常工作。我正在尝试通过 HTTP 将图像流式传输到浏览器。

    [Route("api/v1/camera/live/stream")]
    [HttpGet]
    public HttpResponseMessage GetStream()
    {
        logger.Trace($"GET api/v1/camera/live/stream called");

        var response = Request.CreateResponse();
        response.Content = new PushStreamContent(new Action<Stream, HttpContent, TransportContext>(
            async (stream, content, tansportContext) =>
            {
                try
                {
                    StreamWriter writer = new StreamWriter(stream);

                    while (HttpContext.Current.Response.IsClientConnected)
                    {

                        var image = databuffer.Get<CameraFrame>().LastOrDefault();
                        if (image != null)
                        {
                            MemoryStream ms = new MemoryStream();
                            ms.SetLength(0);
                            ms.WriteTo(BytesOf(databuffer.Get<CameraFrame>().Last().Image));

                            writer.WriteLine("--boundary");
                            writer.WriteLine("Content-Type: image/jpeg");
                            writer.WriteLine($"Content-length: {ms.Length}");
                            writer.WriteLine();
                            writer.Write(ms.GetBuffer());

                            writer.Flush();
                        }

                        await Task.Delay(33);
                    }
                }
                catch (Exception ex)
                {
                    logger.Error($"Streaming error", ex);
                    throw;
                }

                logger.Trace("streaming ended");

            }));
        response.Content.Headers.ContentType =
            MediaTypeHeaderValue.Parse("multipart/x-mixed-replace; boundary=--boundary");
        return response;
    }

    private MemoryStream BytesOf(Bitmap image)
    {
        MemoryStream ms = new MemoryStream();
        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        return ms;
    }

databuffer.Get() 不断地被相机填充位图帧。

当我运行上面的代码都可以正常编译。但是当我使用 chrome 导航到 URL 它不显示图像。

Answer 1

好的，我已经解决了。主要是我没有正确地做流。

[Route("api/v1/camera/live/stream")]
    [HttpGet]
    public HttpResponseMessage GetStream()
    {
        logger.Trace($"GET api/v1/camera/live/stream called");

        var response = Request.CreateResponse(HttpStatusCode.PartialContent);
        response.Content = new PushStreamContent(new Action<Stream, HttpContent, TransportContext>(async (stream, content, tansportContext) =>
        {
            EventHandler<AcquiredDataEventArgs<CameraFrame>> handler = (_, __) => { };
            try
            {
                MjpegWriter writer = new MjpegWriter(stream);
                handler = (s, e) => writer.Write(e.Data.Image.GetJpegStream());

                camera.DataAcquired += handler;
                while (HttpContext.Current.Response.IsClientConnected)
                {
                    await Task.Delay(100);
                }
                camera.DataAcquired -= handler;


            }
            catch (Exception ex)
            {
                logger.Error($"Streaming error", ex);
                throw;
            }
            logger.Trace("streaming ended");

        }));

        response.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/x-mixed-replace; boundary=--boundary");

        return response;
    }

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