要在 OpenCV 中处理相机的预览帧,我需要访问原始像素数据/字节。所以,有新的 SoftwareBitmap,它应该正好提供这个。
有一个example对于 c#,但在 visual c++ 中我无法获得 IMemoryBufferByteAccess (见备注)界面工作。
异常代码:
// Capture the preview frame
return create_task(_mediaCapture->GetPreviewFrameAsync(videoFrame))
.then([this](VideoFrame^ currentFrame)
{
// Collect the resulting frame
auto previewFrame = currentFrame->SoftwareBitmap;
auto buffer = previewFrame->LockBuffer(Windows::Graphics::Imaging::BitmapBufferAccessMode::ReadWrite);
auto reference = buffer->CreateReference();
// Get a pointer to the pixel buffer
byte* pData = nullptr;
UINT capacity = 0;
// Obtain ByteAccess
ComPtr<IUnknown> inspectable = reinterpret_cast<IUnknown*>(buffer);
// Query the IBufferByteAccess interface.
Microsoft::WRL::ComPtr<IMemoryBufferByteAccess> bufferByteAccess;
ThrowIfFailed(inspectable.As(&bufferByteAccess)); // ERROR ---> Throws HRESULT = E_NOINTERFACE
// Retrieve the buffer data.
ThrowIfFailed(bufferByteAccess->GetBuffer(_Out_ &pData, _Out_ &capacity)); // ERROR ---> Throws HRESULT = E_NOINTERFACE, because bufferByteAccess is null
我也试过这个:
HRESULT hr = ((IMemoryBufferByteAccess*)reference)->GetBuffer(&pData, &capacity);
HRESULT 没问题,但我无法访问 pData -> Access Violation reading Memory。
感谢您的帮助。
最佳答案
您应该在 reinterpret_cast 中使用引用而不是缓冲区。
#include "pch.h"
#include <wrl\wrappers\corewrappers.h>
#include <wrl\client.h>
MIDL_INTERFACE("5b0d3235-4dba-4d44-865e-8f1d0e4fd04d")
IMemoryBufferByteAccess : IUnknown
{
virtual HRESULT STDMETHODCALLTYPE GetBuffer(
BYTE **value,
UINT32 *capacity
);
};
auto previewFrame = currentFrame->SoftwareBitmap;
auto buffer = previewFrame->LockBuffer(BitmapBufferAccessMode::ReadWrite);
auto reference = buffer->CreateReference();
ComPtr<IMemoryBufferByteAccess> bufferByteAccess;
HRESULT result = reinterpret_cast<IInspectable*>(reference)->QueryInterface(IID_PPV_ARGS(&bufferByteAccess));
if (result == S_OK)
{
WriteLine("Get interface successfully");
BYTE* data = nullptr;
UINT32 capacity = 0;
result = bufferByteAccess->GetBuffer(&data, &capacity);
if (result == S_OK)
{
WriteLine("get data access successfully, capacity: " + capacity);
}
}
关于c++ - WinRT C++ (Win10) 从 SoftwareBitmap/BitmapBuffer 访问字节,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31841790/