AsfMojo - asp.net MVC / Extract Frame from WMV C# Cache

问题

I am using AsfMojo (in a handler) in my MVC application to extract a bmp from WMV file, it works great on my localhost IIS7, however the image does not show when I publish the application to our hosting service.

the view script:

 <img id="Image1" alt="image"  src="ImageHandler.ashx?img=CT0001.wmv" height="512" width="512" />

The handler script:

       string videoname = System.Web.HttpContext.Current.Server.MapPath("Video/" + sImageFileName);
            if(File.Exists(videoname)) 
                {
                Bitmap bmp = AsfImage.FromFile(videoname).AtOffset(timeOffset);
                bmp.Save(objMemoryStream, ImageFormat.Png);
                byte[] imageContent = new byte[objMemoryStream.Length];
                objMemoryStream.Position = 0;
                objMemoryStream.Read(imageContent, 0, (int)objMemoryStream.Length);
                context.Response.ContentType = "image/jpeg";
                context.Response.BinaryWrite(imageContent);
                context.Response.Cache.SetExpires(DateTime.Now.AddMinutes(5));
                context.Response.Cache.SetMaxAge(TimeSpan.FromMinutes(5));

Here is the error message when I tried to display the image in a new window using Chrome:

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[ArgumentNullException: Value cannot be null.
Parameter name: image]
   System.Drawing.Graphics.DrawImage(Image image, Int32 x, Int32 y, Int32 width, Int32 height) +1133063
   DirectshowTest.ImageHandler.ProcessRequest(HttpContext context) in E:\..\projects\DirectshowTest\DirectshowTest\ImageHandler.ashx.cs:40
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +341
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69

I suspect becasue of the size of the wmv file, the handler script does not wait until it reads all frames in the file in this line:

 Bitmap bmp = AsfImage.FromFile(videoname).AtOffset(timeOffset);

I tried to cache the contnet response without any luck. Is there a way to check if the file has completely read before generating the image.

I would appreciate your suggestions, thanks in advance.

来源：https://stackoverflow.com/questions/14395238/asfmojo-asp-net-mvc-extract-frame-from-wmv-c-sharp-cache

标签

asp.net-mvc

wmv