UWP 相机预览："No suitable transform was found to encode or decode"

Question

我正在 UWP 中预览带有 CaptureElement 的相机。但为什么在使用某些分辨率时会出现错误："No suitable transform was found to encode or decode"？使用网络摄像头时会发生

我在使用此方法时没有收到错误消息：mediacapture.VideoDeviceController.SetMediaStreamPropertiesAsync(...)。但是如果我使用这种方法，捕获元素不会缩放到我想要的分辨率（捕获元素将它的 strech 属性设置为 none 因为我不想质量损失）

        try
        {
            MediaCaptureInitializationSettings mediacapturesettings = new MediaCaptureInitializationSettings { VideoDeviceId = DeviceInfo.Id };
            await mediacapture.InitializeAsync(mediacapturesettings);
        }
        catch (Exception exception)
        {
            var dialog = new MessageDialog(exception.Message);
            await dialog.ShowAsync();
        }


        captureelement.Source = mediacapture;
        captureelement.FlowDirection = Windows.UI.Xaml.FlowDirection.LeftToRight;

        await mediacapture.StartPreviewAsync();
        // await mediacapture.VideoDeviceController.SetMediaStreamPropertiesAsync(MediaStreamType.VideoPreview, Resolution.EncodingProperties);
        await mediacapture.SetEncodingPropertiesAsync(MediaStreamType.VideoPreview, Resolution.EncodingProperties,null);

        VideoRotation currentrotation = Rotation;
        mediacapture.SetPreviewRotation(currentrotation);

Answer 1

I don't get the error when i use this method: mediacapture.VideoDeviceController.SetMediaStreamPropertiesAsync(...). but if i use this method, the captureelement doesn't get scaled to the resolution i want .

It only happens the first time i callstartpreview().

我已经在内部咨询并得到了回复。这个问题可能与图形驱动程序有关。您的图形驱动程序可能要求您的相机设备预览在您调用 MediaCapture.SetEncodingPropertiesAsync 之前处于运行状态，因此您收到此错误并且仅在第一次收到。

i want to know the difference between the two methods.

区别：

MediaCapture.SetEncodingPropertiesAsync 在相机水槽上设置属性。您可以在这里设置相机不支持的分辨率和旋转，然后编码器将工作以转换为所需的格式。
MediaCapture.VideoDeviceController.SetMediaStreamPropertiesAsync 在源上设置属性。您只能设置相机支持的配置。

因此预览 window 的大小由 Xaml CaptureElement 控制。如果你正在使用VideoDeviceController.SetMediaStreamPropertiesAsync并且想要调整预览window的大小，你只能设置Stretch="UniformToFill"让预览window填充父元素。

UWP 相机预览："No suitable transform was found to encode or decode"

UWP Camera preview: "No suitable transform was found to encode or decode"

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