BitmapDecoder to read a Ico fails

Question

I'm trying to download an .ico and save it to .jpg to show on a Image control, but BitmapDecoder.CreateAsync(BitmapDecoder.IcoDecoderId, stream) throw except and said "The image is unrecognized. (Exception from HRESULT: 0x88982F60)"

var request = (HttpWebRequest)WebRequest.Create("http://www.cnn.com/favicon.ico");                
var webResponse = await request.GetResponseAsync();
var responseStream = webResponse.GetResponseStream();

StorageFile localIconFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("cnn.ico", CreationCollisionOption.ReplaceExisting);

byte[] buffer = new byte[4096];
int bytesRead = 0;
using (var stream = await localIconFile.OpenStreamForWriteAsync())
{
    while ((bytesRead = responseStream.Read(buffer, 0, buffer.Length)) != 0)
    {
        stream.Write(buffer, 0, bytesRead);
    }
}

var resultStream = await localIconFile.OpenAsync(FileAccessMode.Read);

var decoder = await BitmapDecoder.CreateAsync(BitmapDecoder.IcoDecoderId, resultStream);
var provider = await decoder.GetPixelDataAsync();
var pixelData = provider.DetachPixelData();

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Shi Bai