使用自己实现的Renderer Filter+GDI解码和播放视频

￡神魔★判官ぃ 2022-07-15 02:55 167阅读 0赞

[完整源码][Link 1]

本篇文章自己实现了DirectShow的渲染filter来播放视频，我们设定为只接收RGB32格式的数据，DirectShow会自动帮我们解码、转换颜色格式，只需要拷贝到bitmap里再用GDI显示就行了

使用DirectShow前需要安装解码器，否则只能解码avi、wmv等少数格式，推荐[LVAFilters][]，这是基于FFMPEG的解码器

使用了DirectShow samples里的基类，已经编译好放在baseclasses目录了，参考微软的文档：[CBaseRenderer class][]

Decoder.h：

#pragma once
    #include <streams.h>
    #include <functional>
    
    
    class CDecoder : private CBaseVideoRenderer
    {
    public:
    	CDecoder(LPCWSTR fileName, HRESULT* phr);
    	virtual ~CDecoder() = default;
    
    	virtual void RunVideo();
    	virtual void PauseVideo();
    	virtual void StopVideo();
    
    	virtual void GetVideoSize(SIZE& size);
    
    	// 设置需要呈现时的回调函数
    	virtual void SetOnPresent(std::function<void(IMediaSample*)>&& onPresent);
    
    protected:
    	CComPtr<IGraphBuilder> m_graph;
    	CComPtr<IMediaControl> m_control;
    	CComPtr<IBaseFilter> m_source;
    
    	SIZE m_videoSize;
    	// 需要呈现时被调用
    	std::function<void(IMediaSample*)> m_onPresent;
    
    	// CBaseVideoRenderer
    
    private:
    
    	HRESULT DoRenderSample(IMediaSample *pMediaSample);
    	HRESULT CheckMediaType(const CMediaType *);
    };

Decoder.cpp：

#include "stdafx.h"
    #include "Decoder.h"
    
    
    CDecoder::CDecoder(LPCWSTR fileName, HRESULT* phr) :
    	CBaseVideoRenderer(CLSID_NULL, _T("Renderer"), NULL, &(*phr = NOERROR))
    {
    	AddRef(); // 防止多次析构
    
    	*phr = m_graph.CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER);
    	*phr = m_graph.QueryInterface(&m_control);
    
    	*phr = m_graph->AddFilter(this, L"Renderer");
    	*phr = m_graph->AddSourceFilter(fileName, L"Source", &m_source);
    
    	// 连接源和渲染器
    	CComPtr<IEnumPins> enumPins;
    	CComPtr<IPin> sourcePin;
    	CBasePin* rendererPin = GetPin(0);
    	PIN_DIRECTION pinDir;
    
    	m_source->EnumPins(&enumPins);
    	while (enumPins->Next(1, &sourcePin, NULL) == S_OK)
    	{
    		sourcePin->QueryDirection(&pinDir);
    		if (pinDir == PINDIR_OUTPUT)
    			break;
    		sourcePin.Release();
    	}
    	enumPins.Release();
    
    	*phr = m_graph->Connect(sourcePin, rendererPin);
    
    	// 获取视频尺寸
    	CMediaType mediaType;
    	*phr = rendererPin->ConnectionMediaType(&mediaType);
    	if (mediaType.formattype == FORMAT_VideoInfo)
    	{
    		VIDEOINFOHEADER* info = (VIDEOINFOHEADER*)mediaType.pbFormat;
    		m_videoSize.cx = info->bmiHeader.biWidth;
    		m_videoSize.cy = info->bmiHeader.biHeight;
    	}
    	else
    	{
    		TRACE(_T("未知的FormatType\n"));
    		m_videoSize.cx = 800;
    		m_videoSize.cy = 600;
    	}
    }
    
    void CDecoder::RunVideo()
    {
    	TRACE(_T("Run\n"));
    	HRESULT hr = m_control->Run();
    }
    
    void CDecoder::PauseVideo()
    {
    	TRACE(_T("Pause\n"));
    	HRESULT hr = m_control->Pause();
    }
    
    void CDecoder::StopVideo()
    {
    	TRACE(_T("Stop\n"));
    	HRESULT hr = m_control->Stop();
    }
    
    void CDecoder::GetVideoSize(SIZE& size)
    {
    	size = m_videoSize;
    }
    
    void CDecoder::SetOnPresent(std::function<void(IMediaSample*)>&& onPresent)
    {
    	m_onPresent = std::move(onPresent);
    }
    
    // CBaseVideoRenderer
    
    HRESULT CDecoder::CheckMediaType(const CMediaType * mediaType)
    {
    	if (mediaType->majortype == MEDIATYPE_Video && mediaType->subtype == MEDIASUBTYPE_RGB32)
    		return S_OK;
    	return VFW_E_INVALIDMEDIATYPE;
    }
    
    HRESULT CDecoder::DoRenderSample(IMediaSample *pMediaSample)
    {
    	if (!m_onPresent._Empty())
    		m_onPresent(pMediaSample);
    	return S_OK;
    }

使用方法：

HRESULT hr;
    	m_decoder = new CDecoder(L"E:\\pump it.avi", &hr);
    	m_decoder->SetOnPresent(std::bind(&CRenderFilterGDIDlg::OnPresent, this, std::placeholders::_1));
    
    	m_decoder->GetVideoSize(m_videoSize);
    	m_dc.Create(m_videoSize.cx, m_videoSize.cy, 32);
    
    	m_decoder->RunVideo();
    
    // ......
    
    void CRenderFilterGDIDlg::OnPresent(IMediaSample* mediaSample)
    {
    	BYTE* sampleBuf = NULL;
    	if (FAILED(mediaSample->GetPointer(&sampleBuf)))
    		return;
    	
    	// 假设每行之间没有多余的字节
    	ASSERT(mediaSample->GetActualDataLength() == m_videoSize.cx * m_videoSize.cy * 4);
    	m_dcLock.Lock();
    	// RGB位图都是从下到上储存的
    	memcpy(m_dc.GetPixelAddress(0, m_videoSize.cy - 1), sampleBuf, m_videoSize.cx * m_videoSize.cy * 4);
    	m_dcLock.Unlock();
    
    	Invalidate(FALSE);
    }

[Link 1]: https://github.com/xfgryujk/DecodeVideo/tree/master/RenderFilterGDI
[LVAFilters]: https://github.com/Nevcairiel/LAVFilters/releases
[CBaseRenderer class]: https://msdn.microsoft.com/en-us/library/dd374163%28v=vs.85%29.aspx