0

我有基于此示例的代码；https://github.com/microsoft/Windows-universal-samples/tree/master/Samples/CameraGetPreviewFrame。每次都行；

await _mediaCapture.GetPreviewFrameAsync(_currentVideoFrame);

被击中我们似乎泄漏了内存。我没有收拾什么？我也尝试过每次都创建模板框架并在每个循环上对其进行处理和归零——这似乎也不起作用。

我已经回到微软的原始样本，它似乎也泄漏了。这是我的代码； 

await Task.Run(async () =>
{
    try
    {
        var videoEncodingProperties = 
            _mediaCapture.VideoDeviceController.GetMediaStreamProperties
                (MediaStreamType.VideoPreview) as VideoEncodingProperties;

        Debug.Assert(videoEncodingProperties != null, nameof(videoEncodingProperties) + " != null");

        _currentVideoFrame = new VideoFrame(BitmapPixelFormat.Gray8,
            (int) videoEncodingProperties.Width,
            (int) videoEncodingProperties.Height);

        TimeSpan? lastFrameTime = null;

        while (_mediaCapture.CameraStreamState == CameraStreamState.Streaming)
        {
            token.ThrowIfCancellationRequested();

            await _mediaCapture.GetPreviewFrameAsync(_currentVideoFrame);

            if (!lastFrameTime.HasValue ||
                lastFrameTime != _currentVideoFrame.RelativeTime)
            {
                await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync
                    (CoreDispatcherPriority.Normal,
                    () =>
                    {
                        try
                        {
                            Debug.Assert(_currentVideoFrame != null,
                                        $"{nameof(_currentVideoFrame)} != null");

                            var bitmap = _currentVideoFrame.SoftwareBitmap.AsBitmap();

                            float focalLength = _cameraOptions == CameraOptions.Front ? AppSettings.FrontCameraFocalLength : AppSettings.RearCameraFocalLength;

                            _frameProcessor.ProcessFrame(bitmap, focalLength);
                        }
                        catch (Exception ex)
                        {
                            Debug.WriteLine($"Exception: {ex}");
                        }
                    });

                lastFrameTime = _currentVideoFrame.RelativeTime;
            }
        }
    }
    catch (Exception ex)
    {
        Debug.WriteLine($"Exception: {ex}");
    }
},
token);

这应该只是获取帧并将它们通过_frameProcessor.ProcessFrame()调用，但即使它什么都不做（我删除了除 GetPreviewFrameAsync 之外的所有内容）它也会泄漏。

要重复该问题，请从以下位置下载示例；https://github.com/microsoft/Windows-universal-samples/tree/master/Samples/CameraGetPreviewFrame。在 Windows 10 v 1903 (18362.175) 下使用诊断工具 (Debug->Windows->Show Diagnostic tools) 远程运行调试器中的示例到 Surface Pro 4 (i5-6300U @2.4GHz)。打开显示帧复选框并在按下 GetPreviewFrameAsync 按钮时观察内存。记忆如下所示，每次上升都是我按下按钮；

内存泄漏

4

1 回答 1

0

在我们的代码中使用MediaFrameReader API可以很好地解决这个错误，并且可能会稍微响应一些。Microsoft 现在已在GetPreviewFrameAsync 文档页面中添加了一条注释以指出这一点。

这对我们有用；

...
private MediaFrameReader _mediaFrameReader;
...

private async Task InitializeCameraAsync()
{
    if (_mediaCapture == null)
    {
         _mediaCapture = new MediaCapture();
         var frameSourceGroups = await MediaFrameSourceGroup.FindAllAsync();
         var selectedGroup = frameSourceGroups.FirstOrDefault(x => x.Id.Equals(_camera.UwpDeviceInfo.Id));

         try
         {
             var mediaInitSettings = new MediaCaptureInitializationSettings
             {
                 SourceGroup = selectedGroup,
                 VideoDeviceId = _camera.UwpDeviceInfo.Id,
                 AudioDeviceId = string.Empty,
                 StreamingCaptureMode = StreamingCaptureMode.Video,
                 MemoryPreference = MediaCaptureMemoryPreference.Cpu
             };

             await _mediaCapture.InitializeAsync(mediaInitSettings);

             _isInitialized = true;
         }
         catch (UnauthorizedAccessException)
         {
...
         }
         catch (Exception ex)
         {
...
         }
...

         // Set-up for frameProcessing
         var sourceInfo = selectedGroup?.SourceInfos.FirstOrDefault(info =>
             info.SourceKind == MediaFrameSourceKind.Color);
...                   
         var colorFrameSource = _mediaCapture.FrameSources[sourceInfo.Id];
         var preferredFormat = colorFrameSource.SupportedFormats
             .OrderByDescending(x => x.VideoFormat.Width)
             .FirstOrDefault(x => x.VideoFormat.Width <= 1920 &&
                  x.Subtype.Equals(MediaEncodingSubtypes.Nv12, StringComparison.OrdinalIgnoreCase));

         await colorFrameSource.SetFormatAsync(preferredFormat);

         _mediaFrameReader = await _mediaCapture.CreateFrameReaderAsync(colorFrameSource);
     }
...
}

...

private void _mediaFrameReader_FrameArrived(MediaFrameReader sender, MediaFrameArrivedEventArgs args)
{
...
        var mediaFrameReference = sender.TryAcquireLatestFrame();
        var videoMediaFrame = mediaFrameReference?.VideoMediaFrame;
        var softwareBitmap = videoMediaFrame?.SoftwareBitmap;

        if (softwareBitmap != null && _frameProcessor != null)
        {
            if (_mediaCapture.CameraStreamState == CameraStreamState.Streaming)
            {
...
                _frameProcessor.ProcessFrame(SoftwareBitmap.Convert(softwareBitmap, 
                        BitmapPixelFormat.Gray8).AsBitmap(), _camera);
...
            }
        }
...
    }
}
于 2019-07-02T11:29:49.857 回答