Question

在UWP C ++ / CX项目中，我尝试从MediaCapture Camera Stream的每一帧截取屏幕截图，并在最后将视频流保存为视频。我的方法：

/// <summary>
/// Records an MP4 video to a StorageFile and adds rotation metadata to it
/// </summary>
/// <returns></returns>
task<void> CameraControl::StartRecordingAsyncStream()
{
//InMemoryRandomAccessStream^ video_stream;
// Calculate rotation angle, taking mirroring into account if necessary
auto rotationAngle = CameraRotationHelper::ConvertSimpleOrientationToClockwiseDegrees(_rotationHelper->GetCameraCaptureOrientation());
auto encodingProfile = MediaProperties::MediaEncodingProfile::CreateMp4(MediaProperties::VideoEncodingQuality::Auto);

encodingProfile->Video->Properties->Insert(RotationKey, rotationAngle);


return create_task(_mediaCapture->StartRecordToStreamAsync(encodingProfile, this->video_stream))
    .then([this]()
{
    _isRecording = true;
    WriteLine("Started recording");


}).then([this](task<void> previousTask)
{
    try
    {
        previousTask.get();
    }
    catch (Exception^ ex)
    {
        // File I/O errors are reported as exceptions
        WriteLine(ex->Message);
    }
});
}

/// <summary>
/// Stops recording a video
/// </summary>
/// <returns></returns>
task<void> CameraControl::StopRecordingAsyncStream()
{
_isRecording = false;

WriteLine("Stopping recording...");
return create_task(_mediaCapture->StopRecordAsync())
    .then([this]()
{
    WriteLine("Stopped recording!");

    });
}


//Loads all frames as images from the stream
void CameraControl::LoadVideoStream(void) {

//TODO: Read all Frames as Thumbnails from "this->video_stream" and store them as Bitmaps, for example in a vector

}

/// <summary>
/// Stores the recorded stream as a MP4 video
/// </summary>
/// <returns></returns>
task<void> CameraControl::StoreRecordingAsync()
{

// Create storage file for the capture
return create_task(_captureFolder->CreateFileAsync("SimpleVideo.mp4", CreationCollisionOption::GenerateUniqueName))
    .then([this](StorageFile^ file)
{

//TODO: Write the "this->video_stream" as a MP4 video to the file

});
}

对于第一个问题，我需要像MP4Decoder那样可以转换流（类似于CapturePhotoToStreamAsync的BitmapDecoder）

关于第二个问题：我知道有一个功能＆＃34; StartRecordToStorageFileAsync＆＃34;。但这不是解决方案，因为保存视频可选择在最后。我不想保存每个视频。

谢谢！

Corono

修改

我尝试实现具有FrameArrived事件的Media Frame Reader。

public : IAsyncOperation<MediaFrameReader> CreateFrameReaderAsync(MediaFrameSource inputSource)

在PC上运行良好，但Win10移动设备上没有找到MediaFrameSource。不知道为什么。

Answer 1

通过MediaCapture，您可以访问SoftwareBitmap中<div [innerHTML]="some_string"></div>的各个帧。我这样做是为了处理C＃中的单个帧，但它应该同样适用于C ++。我的代码基于此示例：https://docs.microsoft.com/en-gb/windows/uwp/audio-video-camera/process-media-frames-with-mediaframereader

如何从UWP C ++项目中的流记录中提取帧？

1 个答案: