public HttpContent AudioContent(FileInfo audio, long start, long end)
 {
     return(new PushStreamContent((outputStream, httpContent, transpContext)
                                  =>
     {
         using (outputStream) // copy file stream vào outputstream theo range trong header
             using (Stream inputStream = audio.Open(FileMode.Open, FileAccess.Read, FileShare.Read))
                 MediaUtilities.CreatePartialContent(inputStream, outputStream, start, end);
         //inputStream.CopyTo(outputStream, MediaUtilities.BufferSize);
     }, MediaUtilities.GetMimeType(audio.Extension)));
 }