Question

我正在尝试在uwp应用程序中获取Rtsp视频的快照。要重现视频，我正在使用vlc.MediaElement库（欢迎对此提出更好的库的任何建议）。目前，我正在使用这种方法获取视频快照：

private async void PhotoButton_Click(object sender, RoutedEventArgs e)
        {

            Media.Pause();
            RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap();
            await renderTargetBitmap.RenderAsync(Media, ((int)Media.Width / 2), ((int)Media.Height / 2));
            ImgPreview.Source = renderTargetBitmap;
            Media.Play();

        }

ImgPreview元素中的结果不错，但是当我使用此功能将其保存到文件中时

private async void SaveButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                StorageLibrary lib = await StorageLibrary.GetLibraryAsync(KnownLibraryId.Pictures);
                StorageFolder folder = lib.SaveFolder;
                StorageFile file = await folder.CreateFileAsync("TestPhoto_" + DateTime.Now.Ticks + ".jpg", CreationCollisionOption.GenerateUniqueName);

                DisplayInformation display = DisplayInformation.GetForCurrentView();
                RenderTargetBitmap rtb = new RenderTargetBitmap();
                await rtb.RenderAsync(ImgPreview);

                IBuffer pixels = await rtb.GetPixelsAsync();
                DataReader data = DataReader.FromBuffer(pixels);
                byte[] bytes = new byte[pixels.Length];
                data.ReadBytes(bytes);
                using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
                {
                    BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, stream);


                    encoder.SetPixelData(
                        BitmapPixelFormat.Bgra8,
                        BitmapAlphaMode.Ignore,
                        (uint)rtb.PixelWidth,
                        (uint)rtb.PixelHeight,
                        display.RawDpiX,
                        display.RawDpiY,
                        bytes);

                    await encoder.FlushAsync();

                    storage.doPut(file.Path, file.Name);
                }
            }
            catch (Exception ex)
            {

            }

        }

结果非常模糊，对于我的应用程序，我需要更高质量的图像。我尝试使用dpi，但唯一的结果是完全移位了带有奇怪对角带的像素图。

有没有办法解决这个问题？感谢您的帮助。

Answer 1

结果非常模糊，对于我的应用程序，我需要更高质量的图像。

我检查了您的代码，发现获得了{strong> ImgPreview 的RenderTargetBitmap，这是没有必要的，您可以直接使用MediaElement的RenderTargetBitmap来避免图像质量下降。

您将获得RenderTargetBitmap的一半尺寸，其以下内容会导致图像质量下降。

await renderTargetBitmap.RenderAsync(Media, ((int)Media.Width / 2), ((int)Media.Height / 2));

请使用原尺寸。

 await renderTargetBitmap.RenderAsync(Media, ((int)Media.Width), ((int)Media.Height));

 ......

 private RenderTargetBitmap renderTargetBitmap;
 private async void SaveButton_Click(object sender, RoutedEventArgs e)
 {
     try
     {
         StorageLibrary lib = await StorageLibrary.GetLibraryAsync(KnownLibraryId.Pictures);
         StorageFolder folder = lib.SaveFolder;
         StorageFile file = await folder.CreateFileAsync("TestPhoto_" + DateTime.Now.Ticks + ".jpg", CreationCollisionOption.GenerateUniqueName);
         DisplayInformation display = DisplayInformation.GetForCurrentView();                 
         IBuffer pixels = await renderTargetBitmap.GetPixelsAsync();
         DataReader data = DataReader.FromBuffer(pixels);
         byte[] bytes = new byte[pixels.Length];
         data.ReadBytes(bytes);
         using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
         {
             BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, stream);


             encoder.SetPixelData(
                 BitmapPixelFormat.Bgra8,
                 BitmapAlphaMode.Ignore,
                 (uint)renderTargetBitmap.PixelWidth,
                 (uint)renderTargetBitmap.PixelHeight,
                 display.RawDpiX,
                 display.RawDpiY,
                 bytes);

             await encoder.FlushAsync();

             //storage.doPut(file.Path, file.Name);
         }
     }
     catch (Exception ex)
     {

     }

 }

在UWP中拍摄流式Rtsp视频的快照

1 个答案: