如何在Windows Phone 8.1中使用MediaCapture設置最大分辨率？

Question

我在Windows Phone 8.1（RT）上工作，我使用MediaCapture拍照（請注意不要對預覽要拍攝的照片感興趣）。 我使用了以下代碼，但是照片的質量很差，僅在拍攝的照片中看到照明光的部分。

private static async Task<DeviceInformation> GetCameraID(Windows.Devices.Enumeration.Panel desiredCamera)
{
    // get available devices for capturing pictures
    DeviceInformation deviceID = (await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture))
        .FirstOrDefault(x => x.EnclosureLocation != null && x.EnclosureLocation.Panel == desiredCamera);

    if (deviceID != null) return deviceID;
    else throw new Exception(string.Format("Camera of type {0} doesn't exist.", desiredCamera));
}

public async Task takeAPicture()
{
    var cameraID = await GetCameraID(Windows.Devices.Enumeration.Panel.Back);
    captureManager = new MediaCapture();

    await captureManager.InitializeAsync(new MediaCaptureInitializationSettings
    {
        StreamingCaptureMode = StreamingCaptureMode.Video,
        PhotoCaptureSource = PhotoCaptureSource.VideoPreview,
        AudioDeviceId = string.Empty,
        VideoDeviceId = cameraID.Id
    });

    var maxResolution = captureManager.VideoDeviceController.GetAvailableMediaStreamProperties(MediaStreamType.Photo).Aggregate((i1, i2) => (i1 as VideoEncodingProperties).Width > (i2 as VideoEncodingProperties).Width ? i1 : i2);
    await captureManager.VideoDeviceController.SetMediaStreamPropertiesAsync(MediaStreamType.Photo, maxResolution);

    StorageFile photoFile = await KnownFolders.PicturesLibrary.CreateFileAsync("myFirstPhoto.jpg", CreationCollisionOption.GenerateUniqueName);
    //take a photo with choosen Encoding

    await captureManager.CapturePhotoToStorageFileAsync(ImageEncodingProperties.CreateJpeg(), photoFile);
    captureManager.Dispose();
}

謝謝您的幫助。

Answer 1

好像您配置MediaCapture來給您“預覽質量”的照片一樣。 改為這樣做：

await captureManager.InitializeAsync(new MediaCaptureInitializationSettings
{
    StreamingCaptureMode = StreamingCaptureMode.Video,
    PhotoCaptureSource = PhotoCaptureSource.Photo, // I believe your bug was here
    AudioDeviceId = string.Empty,
    VideoDeviceId = cameraID.Id
});

或者說真的，只需為大多數這些屬性嘗試默認設置，然后僅將VideoDeviceId設置為選擇攝像機即可。 它應該有助於縮小問題的范圍。

至於設置更高的照片拍攝分辨率，則可能需要執行以下操作：

private async Task SetPhotoResolution()
{
    var resolutions = _captureManager.VideoDeviceController.GetAvailableMediaStreamProperties(MediaStreamType.Photo).Select(x => x as VideoEncodingProperties);

    var maxRes = resolutions.OrderByDescending(x => x.Height * x.Width).FirstOrDefault();

    await _captureManager.VideoDeviceController.SetMediaStreamPropertiesAsync(MediaStreamType.Photo, maxRes);
}

請確保照片分辨率的縱橫比與預覽分辨率的縱橫比匹配，否則在某些手機的邊緣附近可能會出現一些條紋。

另外，我在此電話上測試過的電話僅針對MediaStreamType.Photo流上的GetAvailableMediaStreamProperties調用返回了NV12 VideoEncodingProperties 。 您可能需要在其他設備上處理還包含ImageEncodingProperties的枚舉。