video - 如何在 Windows Phone 8 上从视频文件 (.mp4) 创建缩略图？

Question

我使用 AudioVideoCapture 设备录制视频，但无法获取录制视频的缩略图。请帮我！

Answer 1

你可以试试这个。如果您使用的是 AudioVideoCaptureDevice api。在每帧捕获后进行以下事件（预览缩略图）调用。您可以选择任何您需要的框架。作为第一个。

private AudioVideoCaptureDevice VideoRecordingDevice;
VideoRecordingDevice.PreviewFrameAvailable += previewThumbnail;
bool DisablePreviewFrame = false;

private void previewThumbnail(ICameraCaptureDevice a, object b)
{
    if (!DisablePreviewFrame)
    {
        DisablePreviewFrame = true;
        int frameWidth = (int)VideoRecordingDevice.PreviewResolution.Width;
        int frameHeight = (int)VideoRecordingDevice.PreviewResolution.Height;
    }
    int[] buf = new int[frameWidth * frameHeight];
    VideoRecordingDevice.GetPreviewBufferArgb(buf);
    using (IsolatedStorageFile isoStoreFile = IsolatedStorageFile.GetUserStoreForApplication())
    {
        var fileName = "temp.jpg";

        if (isoStoreFile.FileExists(fileName))
            isoStoreFile.DeleteFile(fileName);
        using (IsolatedStorageFileStream isostream = isoStoreFile.CreateFile(fileName))
        {
            WriteableBitmap wb = new WriteableBitmap(frameWidth, frameWidth);
            Array.Copy(buf, wb.Pixels, buf.Length);
            wb.SaveJpeg(isostream, 120, 120, 0, 60);
            isostream.Close();
        }
    }
}