DirectX 11 render BGRA32 Frame

Question

First time trying to render something and I have big troubles... I am using DirectN library and SwapChainSurface class from KlearTouch.MediaPlayer. I am trying to render BGRA32 frame using D3D11Device.

For this I have slightly modified OnNewSurfaceAvailable:

public void OnNewSurfaceAvailable2(Action updateSurface)
{
    if (rendering)
    {
        return;
    }

    try
    {
        if (this.swapChain is null || swapChainComObject is null)
        {
            return;
        }

        swapChainComObject.GetDesc(out var swapChainDesc).ThrowOnError();

        if (swapChainDesc.BufferDesc.Width != PanelWidth || swapChainDesc.BufferDesc.Height != PanelHeight)
        {
            swapChainComObject.ResizeBuffers(2, PanelWidth, PanelHeight, DXGI_FORMAT.DXGI_FORMAT_UNKNOWN, 0).ThrowOnError();
        }

        var device = swapChain.Object.GetDevice1().Object.As();

        device.GetImmediateContext(out var context);

        // context.ClearRenderTargetView(renderTargetView.Object, new []{0f, 1f, 1f, 1f});

        updateSurface(device, context);

        swapChainComObject.Present(1, 0).ThrowOnError();
    }
    catch (ObjectDisposedException)
    {
        Reinitialize();
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine("
Exception: " + ex, nameof(SwapChainSurface) + '.' + nameof(OnNewSurfaceAvailable));
    }

    rendering = false;
}

OnSurfaceAvailable2 is called from:

void VideoFrameArrived(Bgra32VideoFrame frame)
    {
        DispatcherQueue.TryEnqueue(() =>
        {
            previewSurface.OnNewSurfaceAvailable2((device, context) =>
            {
                var size = frame.m_height * frame.m_height * 4;

                D3D11_TEXTURE2D_DESC td;
                td.ArraySize = 1;
                td.BindFlags = (uint) D3D11_BIND_FLAG.D3D11_BIND_SHADER_RESOURCE;
                td.Usage = D3D11_USAGE.D3D11_USAGE_DYNAMIC;
                td.CPUAccessFlags = (uint) D3D11_CPU_ACCESS_FLAG.D3D11_CPU_ACCESS_WRITE;
                td.Format = DXGI_FORMAT.DXGI_FORMAT_B8G8R8A8_UNORM;
                td.Height = (uint) frame.m_height;
                td.Width = (uint) frame.m_width;
                td.MipLevels = 1;
                td.MiscFlags = 0;
                td.SampleDesc.Count = 1;
                td.SampleDesc.Quality = 0;

                D3D11_SUBRESOURCE_DATA srd;
                srd.pSysMem = frame.m_pixelBuffer;
                srd.SysMemPitch = (uint) frame.m_height;
                srd.SysMemSlicePitch = 0;

                var texture = device.CreateTexture2D(td, new []{srd});

                var mappedResource = context.Map(texture.Object, 0, D3D11_MAP.D3D11_MAP_WRITE_DISCARD);

                var mappedData = mappedResource.pData;
                

                unsafe
                {
                    Buffer.MemoryCopy(frame.m_pixelBuffer.ToPointer(), mappedData.ToPointer(), size, size);
                }

                // Just for debug
                var pixelsInFrame = new byte[size];
                var pixelsInResource = new byte[size];

                Marshal.Copy(frame.m_pixelBuffer, pixelsInFrame, 0, size);
                Marshal.Copy(mappedResource.pData, pixelsInResource, 0, size);
                
                context.Unmap(texture.Object, 0);
            });
        });
    }

Problem is that I can't see anything rendered and surface stay black and I assume it should not be.

Update: Project repository

Update 2:

I solved my issue. I had too little knowledge about DX11 so I had to study more how things work there. With this knowledge I updated repository which can display preview from black magic design card. It is just example with many issues so be careful and feel free to look for or inspiration there.

user_1641220 · Answer

There's a various amount of issues here.

First on frame arrived, you have

var texture = device.CreateTexture2D(td, new []{srd});

So your create a texture, but you do not use it anywhere, it needs to be blitted to the swapchain (can do a CopyResource on device context or draw a full screen triangle/quad).

Note that CopyResource will only work if your swapchain has the same size as your incoming texture, which is rather unlikely, so you will have to draw a blit with a shader most likely.

Also you actually copying the data in the texture twice :

 var texture = device.CreateTexture2D(td, new []{srd});

Since you provide initial data, the content is already there.

also, pitch is incorrect : srd.SysMemPitch = (uint) frame.m_height;

pitch is the length (in bytes) of a line, so it should be :

srd.SysMemPitch = frame.GetRowBytes();

Please also note that in case of a non converted Decklink frame, GetRowBytes can be different from width*4 (they can align row size to multiple of 16/32 or other values).

Next, in the case of resource map, the following is also incorrect :

unsafe
{
    Buffer.MemoryCopy(frame.m_pixelBuffer.ToPointer(), mappedData.ToPointer(), size, size);
}

You are not checking the pitch/stride requirement of a texture (which can be different as well),

so you need to do :

if (mappedResource.RowPitch == frame.GetRowBytes())
{
    //here you can use a direct copy as above
}
else
{
   //here you need to copy data line per line
}

DirectX 11 render BGRA32 Frame

Update: Project repository

Update 2:

1 Answers