Media Player Classic - HC 源代码分析 2：核心类 （CMainFrame）（1）

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Media Player Classic - HC 源代码分析系列文章列表：

Media Player Classic - HC 源代码分析 1：整体结构

Media Player Classic - HC 源代码分析 2：核心类 （CMainFrame）（1）

Media Player Classic - HC 源代码分析 3：核心类 （CMainFrame）（2）

Media Player Classic - HC 源代码分析 4：核心类 （CMainFrame）（3）

Media Player Classic - HC 源代码分析 5：关于对话框 （CAboutDlg）

Media Player Classic - HC 源代码分析 6：MediaInfo选项卡 （CPPageFileMediaInfo）

Media Player Classic - HC 源代码分析 7：详细信息选项卡（CPPageFileInfoDetails）

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上一篇文章概括性的介绍了Media Player Classic - Home Cinema (mpc-hc)播放器的源代码：Media Player Classic - HC 源代码分析 1：整体结构
现在可以开始看看具体的源代码了。

mpc-hc最核心的类名字叫CMainFrame，它的定义位于MainFrm.h文件中

CMainFrame定义非常的长，包含了视频播放器的方方面面，一共900多行，在这里应该快放不下了。因此我删掉了很多代码，只保留了部分代码。关键的函数上面都写上了注释。

class CMainFrame : public CFrameWnd, public CDropTarget
{
...

// TODO: wrap these graph objects into a class to make it look cleaner
//各种DirectShow接口
//CComPtr被称为智能指针，是ATL提供的一个模版类，能够从语法上自动完成COM的AddRef和Release。
CComPtr<IGraphBuilder2> m_pGB;
CComQIPtr<IMediaControl> m_pMC;
CComQIPtr<IMediaEventEx> m_pME;
CComQIPtr<IVideoWindow> m_pVW;
//这里也可以获得
//分辨率，比特率，帧率
//经过测试，貌似这里取不到值 = =
CComQIPtr<IBasicVideo> m_pBV;
//音量，均衡器等信息
CComQIPtr<IBasicAudio> m_pBA;
CComQIPtr<IMediaSeeking> m_pMS;
CComQIPtr<IVideoFrameStep> m_pFS;
//接收端质量信息：抖动，抖动，视音频同步情况等。。。
CComQIPtr<IQualProp, &IID_IQualProp> m_pQP;
//缓存信息
CComQIPtr<IBufferInfo> m_pBI;
CComQIPtr<IAMOpenProgress> m_pAMOP;
CComPtr<IVMRMixerControl9> m_pVMRMC;
CComPtr<IMFVideoDisplayControl> m_pMFVDC;
CComPtr<IMFVideoProcessor> m_pMFVP;
CComPtr<IVMRWindowlessControl9> m_pVMRWC;
...
void SetVolumeBoost(UINT nAudioBoost);
void SetBalance(int balance);

// subtitles
CCritSec m_csSubLock;

CList<SubtitleInput> m_pSubStreams;
POSITION m_posFirstExtSub;
ISubStream* m_pCurrentSubStream;

SubtitleInput* GetSubtitleInput(int& i, bool bIsOffset = false);

friend class CTextPassThruFilter;

// windowing

CRect m_lastWindowRect;
CPoint m_lastMouseMove;

void ShowControls(int nCS, bool fSave = false);
void SetUIPreset(int iCaptionMenuMode, UINT nCS);

void SetDefaultWindowRect(int iMonitor = 0);
void SetDefaultFullscreenState();
void RestoreDefaultWindowRect();
void ZoomVideoWindow(bool snap = true, double scale = ZOOM_DEFAULT_LEVEL);
double GetZoomAutoFitScale(bool bLargerOnly = false) const;

void SetAlwaysOnTop(int iOnTop);

// dynamic menus
// 动态菜单
void SetupOpenCDSubMenu();
void SetupFiltersSubMenu();
void SetupAudioSwitcherSubMenu();
void SetupSubtitlesSubMenu();
...

CMenu m_popupmain, m_popup;
CMenu m_opencds;
CMenu m_filters, m_subtitles, m_audios;
CMenu m_language;
...

// chapters (file mode)
CComPtr<IDSMChapterBag> m_pCB;
void SetupChapters();

// chapters (dvd mode)
void SetupDVDChapters();

void SetupIViAudReg();

void AddTextPassThruFilter();

int m_nLoops;
UINT m_nLastSkipDirection;

bool m_fCustomGraph;
...

public:
void StartWebServer(int nPort);
void StopWebServer();

CString GetStatusMessage() const;
int GetPlaybackMode() const { return m_iPlaybackMode; }
void SetPlaybackMode(int iNewStatus);
bool IsMuted() { return m_wndToolBar.GetVolume() == -10000; }
int GetVolume() { return m_wndToolBar.m_volctrl.GetPos(); }

public:
CMainFrame();
DECLARE_DYNAMIC(CMainFrame)

// Attributes
public:
bool m_fFullScreen;
bool m_fFirstFSAfterLaunchOnFS;
bool m_fStartInD3DFullscreen;
bool m_fHideCursor;
CMenu m_navaudio, m_navsubtitle;

CComPtr<IBaseFilter> m_pRefClock; // Adjustable reference clock. GothSync
CComPtr<ISyncClock> m_pSyncClock;
...

CControlBar* m_pLastBar;

protected:
MPC_LOADSTATE m_iMediaLoadState;
bool m_bFirstPlay;

bool m_fAudioOnly;
dispmode m_dmBeforeFullscreen;
CString m_LastOpenFile, m_LastOpenBDPath;
HMONITOR m_LastWindow_HM;

DVD_DOMAIN m_iDVDDomain;
DWORD m_iDVDTitle;
double m_dSpeedRate;
double m_ZoomX, m_ZoomY, m_PosX, m_PosY;
int m_AngleX, m_AngleY, m_AngleZ;

//操作 Operations
//打开一个媒体
bool OpenMediaPrivate(CAutoPtr<OpenMediaData> pOMD);
//关闭媒体
void CloseMediaPrivate();
void DoTunerScan(TunerScanData* pTSD);

CWnd* GetModalParent();

void OpenCreateGraphObject(OpenMediaData* pOMD);
//打开文件
void OpenFile(OpenFileData* pOFD);
//打开DVD
void OpenDVD(OpenDVDData* pODD);
//打开摄像头
void OpenCapture(OpenDeviceData* pODD);
HRESULT OpenBDAGraph();
void OpenCustomizeGraph();
//设置视频窗口
void OpenSetupVideo();
//设置音量
void OpenSetupAudio();
void OpenSetupInfoBar();
void UpdateChapterInInfoBar();
//打开统计工具条
void OpenSetupStatsBar();
//打开状态工具条
void OpenSetupStatusBar();
// void OpenSetupToolBar();
void OpenSetupCaptureBar();
//设置窗口标题
void OpenSetupWindowTitle(CString fn = _T(""));
void AutoChangeMonitorMode();

bool GraphEventComplete();

friend class CGraphThread;
CGraphThread* m_pGraphThread;
bool m_bOpenedThruThread;

CAtlArray<REFERENCE_TIME> m_kfs;

bool m_fOpeningAborted;
bool m_bWasSnapped;

public:
void OpenCurPlaylistItem(REFERENCE_TIME rtStart = 0);
void OpenMedia(CAutoPtr<OpenMediaData> pOMD);
void PlayFavoriteFile(CString fav);
void PlayFavoriteDVD(CString fav);
bool ResetDevice();
bool DisplayChange();
void CloseMedia();
void StartTunerScan(CAutoPtr<TunerScanData> pTSD);
void StopTunerScan();
HRESULT SetChannel(int nChannel);

void AddCurDevToPlaylist();

bool m_fTrayIcon;
//设置系统托盘图标
void ShowTrayIcon(bool fShow);
void SetTrayTip(CString str);

CSize GetVideoSize() const;
void ToggleFullscreen(bool fToNearest, bool fSwitchScreenResWhenHasTo);
void ToggleD3DFullscreen(bool fSwitchScreenResWhenHasTo);
void MoveVideoWindow(bool fShowStats = false);
void RepaintVideo();
void HideVideoWindow(bool fHide);

OAFilterState GetMediaState() const;
REFERENCE_TIME GetPos() const;
REFERENCE_TIME GetDur() const;
void SeekTo(REFERENCE_TIME rt, bool fSeekToKeyFrame = false);
//设置播放速率
void SetPlayingRate(double rate);

DWORD SetupAudioStreams();
DWORD SetupSubtitleStreams();
//字幕
bool LoadSubtitle(CString fn, ISubStream** actualStream = nullptr, bool bAutoLoad = false);
bool SetSubtitle(int i, bool bIsOffset = false, bool bDisplayMessage = false, bool bApplyDefStyle = false);
void SetSubtitle(ISubStream* pSubStream, bool bApplyDefStyle = false);
void ToggleSubtitleOnOff(bool bDisplayMessage = false);
void ReplaceSubtitle(const ISubStream* pSubStreamOld, ISubStream* pSubStreamNew);
void InvalidateSubtitle(DWORD_PTR nSubtitleId = -1, REFERENCE_TIME rtInvalidate = -1);
void ReloadSubtitle();
HRESULT InsertTextPassThruFilter(IBaseFilter* pBF, IPin* pPin, IPin* pPinto);

void SetAudioTrackIdx(int index);
void SetSubtitleTrackIdx(int index);

void AddFavorite(bool fDisplayMessage = false, bool fShowDialog = true);

// shaders
CAtlList<CString> m_shaderlabels;
CAtlList<CString> m_shaderlabelsScreenSpace;
void SetShaders();
void UpdateShaders(CString label);

// capturing
bool m_fCapturing;
HRESULT BuildCapture(IPin* pPin, IBaseFilter* pBF[3], const GUID& majortype, AM_MEDIA_TYPE* pmt); // pBF: 0 buff, 1 enc, 2 mux, pmt is for 1 enc
bool BuildToCapturePreviewPin(IBaseFilter* pVidCap, IPin** pVidCapPin, IPin** pVidPrevPin,
IBaseFilter* pAudCap, IPin** pAudCapPin, IPin** pAudPrevPin);
bool BuildGraphVideoAudio(int fVPreview, bool fVCapture, int fAPreview, bool fACapture);
bool DoCapture(), StartCapture(), StopCapture();

bool DoAfterPlaybackEvent();
void ParseDirs(CAtlList<CString>& sl);
bool SearchInDir(bool bDirForward, bool bLoop = false);

virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
virtual BOOL PreTranslateMessage(MSG* pMsg);
virtual BOOL OnCmdMsg(UINT nID, int nCode, void* pExtra, AFX_CMDHANDLERINFO* pHandlerInfo);
virtual void RecalcLayout(BOOL bNotify = TRUE);

// DVB capture
void ShowCurrentChannelInfo(bool fShowOSD = true, bool fShowInfoBar = false);

// Implementation
public:
virtual ~CMainFrame();
#ifdef _DEBUG
virtual void AssertValid() const;
virtual void Dump(CDumpContext& dc) const;
#endif

protected:
// control bar embedded members
CChildView m_wndView;

UINT m_nCS;
CPlayerSeekBar m_wndSeekBar;
CPlayerToolBar m_wndToolBar;
CPlayerInfoBar m_wndInfoBar;
CPlayerInfoBar m_wndStatsBar;
CPlayerStatusBar m_wndStatusBar;
CList<CControlBar*> m_bars;

CPlayerSubresyncBar m_wndSubresyncBar;
CPlayerPlaylistBar m_wndPlaylistBar;
CPlayerCaptureBar m_wndCaptureBar;
CPlayerNavigationBar m_wndNavigationBar;
CPlayerShaderEditorBar m_wndShaderEditorBar;
CEditListEditor m_wndEditListEditor;
CList<CSizingControlBar*> m_dockingbars;
...

// Generated message map functions

DECLARE_MESSAGE_MAP()

public:
//打开的时候加载
afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
//关闭的时候加载
afx_msg void OnDestroy();

afx_msg LRESULT OnTaskBarRestart(WPARAM, LPARAM);
afx_msg LRESULT OnNotifyIcon(WPARAM, LPARAM);
afx_msg LRESULT OnTaskBarThumbnailsCreate(WPARAM, LPARAM);

afx_msg LRESULT OnSkypeAttach(WPARAM wParam, LPARAM lParam);

afx_msg void OnSetFocus(CWnd* pOldWnd);
afx_msg void OnGetMinMaxInfo(MINMAXINFO* lpMMI);
afx_msg void OnMove(int x, int y);
afx_msg void OnMoving(UINT fwSide, LPRECT pRect);
afx_msg void OnSize(UINT nType, int cx, int cy);
afx_msg void OnSizing(UINT fwSide, LPRECT pRect);
afx_msg void OnDisplayChange();

afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
afx_msg void OnActivateApp(BOOL bActive, DWORD dwThreadID);
afx_msg LRESULT OnAppCommand(WPARAM wParam, LPARAM lParam);
afx_msg void OnRawInput(UINT nInputcode, HRAWINPUT hRawInput);

afx_msg LRESULT OnHotKey(WPARAM wParam, LPARAM lParam);

afx_msg void OnTimer(UINT_PTR nIDEvent);

afx_msg LRESULT OnGraphNotify(WPARAM wParam, LPARAM lParam);
afx_msg LRESULT OnResetDevice(WPARAM wParam, LPARAM lParam);
afx_msg LRESULT OnRepaintRenderLess(WPARAM wParam, LPARAM lParam);
afx_msg LRESULT OnResumeFromState(WPARAM wParam, LPARAM lParam);
...

// menu item handlers

afx_msg void OnFileOpenQuick();
afx_msg void OnFileOpenmedia();
afx_msg void OnUpdateFileOpen(CCmdUI* pCmdUI);
afx_msg BOOL OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct);
afx_msg void OnFileOpendvd();
afx_msg void OnFileOpendevice();
afx_msg void OnFileOpenCD(UINT nID);
afx_msg void OnFileReopen();
afx_msg void OnFileRecycle();
afx_msg void OnDropFiles(HDROP hDropInfo); // no menu item
...
afx_msg void OnHelpHomepage();
afx_msg void OnHelpCheckForUpdate();
afx_msg void OnHelpToolbarImages();
afx_msg void OnHelpDonate();
//关闭的时候加载
afx_msg void OnClose();

afx_msg void OnLanguage(UINT nID);
afx_msg void OnUpdateLanguage(CCmdUI* pCmdUI);

CMPC_Lcd m_Lcd;

// ==== Added by CASIMIR666
CWnd*           m_pVideoWnd;            // Current Video (main display screen or 2nd)
SIZE            m_fullWndSize;
CFullscreenWnd* m_pFullscreenWnd;
CVMROSD     m_OSD;
bool        m_bRemainingTime;
int         m_nCurSubtitle;
long        m_lSubtitleShift;
REFERENCE_TIME m_rtCurSubPos;
CString     m_strTitle;
bool        m_bToggleShader;
bool        m_bToggleShaderScreenSpace;
bool        m_bInOptions;
bool        m_bStopTunerScan;
bool        m_bLockedZoomVideoWindow;
int         m_nLockedZoomVideoWindow;
bool        m_fSetChannelActive;

void        SetLoadState(MPC_LOADSTATE iState);
void        SetPlayState(MPC_PLAYSTATE iState);
bool        CreateFullScreenWindow();
void        SetupEVRColorControl();
void        SetupVMR9ColorControl();
void        SetColorControl(DWORD flags, int& brightness, int& contrast, int& hue, int& saturation);
void        SetClosedCaptions(bool enable);
LPCTSTR     GetDVDAudioFormatName(const DVD_AudioAttributes& ATR) const;
void        SetAudioDelay(REFERENCE_TIME rtShift);
void        SetSubtitleDelay(int delay_ms);
//void      AutoSelectTracks();
bool        IsRealEngineCompatible(CString strFilename) const;
void        SetTimersPlay();
void        KillTimersStop();

// MPC API functions
void        ProcessAPICommand(COPYDATASTRUCT* pCDS);
void        SendAPICommand(MPCAPI_COMMAND nCommand, LPCWSTR fmt, ...);
void        SendNowPlayingToApi();
void        SendSubtitleTracksToApi();
void        SendAudioTracksToApi();
void        SendPlaylistToApi();
...

protected:
// GDI+
ULONG_PTR m_gdiplusToken;
virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam);
void WTSRegisterSessionNotification();
void WTSUnRegisterSessionNotification();

DWORD m_nMenuHideTick;
UINT m_nSeekDirection;
public:
afx_msg UINT OnPowerBroadcast(UINT nPowerEvent, UINT nEventData);
afx_msg void OnSessionChange(UINT nSessionState, UINT nId);

void EnableShaders1(bool enable);
void EnableShaders2(bool enable);

CAtlList<CHdmvClipInfo::PlaylistItem> m_MPLSPlaylist;
bool m_bIsBDPlay;
bool OpenBD(CString Path);
};

面对一个如此巨大的类，可能会让人感觉到无从下手。我开始研究的时候也不知道该从何学起（实际上找到CMainFrame这个类就花了我挺长时间的，开始的时候根本没找到哪个类才是mpc-hc的最核心的类）。经过一段时间的探索，我发现了打开一个媒体的函数OpenMedia()，这个函数应该是我们每次使用mpc-hc都一定会调用的函数。从这个函数开始学习源代码还是比较合适的。

在看OpenMedia()代码之前，先来看看有哪些函数调用它了。我们可以借助VC2010的“查看调用层次结构”功能来完成这个任务。发现有3个函数：

OnFileOpendevice()//打开一个设备（比如说摄像头）
OnFileOpendvd()//打开一个DVD
OpenCurPlaylistItem()//打开播放列表的一条记录（比如说一个文件）

这3个函数正好对应着mpc-hc的3个功能：打开设备（摄像头），打开DVD，打开文件。这3个函数在这里就不多讲了，以后有机会再进行分析。

下面我们来看看OpenMedia()函数：

//打开媒体（非private）
void CMainFrame::OpenMedia(CAutoPtr<OpenMediaData> pOMD)
{
// shortcut
if (OpenDeviceData* p = dynamic_cast<OpenDeviceData*>(pOMD.m_p)) {
if (m_iMediaLoadState == MLS_LOADED && m_pAMTuner
&& m_VidDispName == p->DisplayName[0] && m_AudDispName == p->DisplayName[1]) {
m_wndCaptureBar.m_capdlg.SetVideoInput(p->vinput);
m_wndCaptureBar.m_capdlg.SetVideoChannel(p->vchannel);
m_wndCaptureBar.m_capdlg.SetAudioInput(p->ainput);
SendNowPlayingToSkype();
return;
}
}

if (m_iMediaLoadState != MLS_CLOSED) {
CloseMedia();
}

//m_iMediaLoadState = MLS_LOADING; // HACK: hides the logo

const CAppSettings& s = AfxGetAppSettings();

bool fUseThread = m_pGraphThread && s.fEnableWorkerThreadForOpening;

if (OpenFileData* p = dynamic_cast<OpenFileData*>(pOMD.m_p)) {
if (!p->fns.IsEmpty()) {
engine_t e = s.m_Formats.GetEngine(p->fns.GetHead());
if (e != DirectShow /*&& e != RealMedia && e != QuickTime*/) {
fUseThread = false;
}
}
} else if (OpenDeviceData* p = dynamic_cast<OpenDeviceData*>(pOMD.m_p)) {
fUseThread = false;
}

// Create D3DFullscreen window if launched in fullscreen
if (s.IsD3DFullscreen() && m_fStartInD3DFullscreen) {
if (s.AutoChangeFullscrRes.bEnabled) {
AutoChangeMonitorMode();
}
CreateFullScreenWindow();
m_pVideoWnd = m_pFullscreenWnd;
m_fStartInD3DFullscreen = false;
} else {
m_pVideoWnd = &m_wndView;
}

if (fUseThread) {
m_pGraphThread->PostThreadMessage(CGraphThread::TM_OPEN, 0, (LPARAM)pOMD.Detach());
m_bOpenedThruThread = true;
} else {
//打开媒体（private）
OpenMediaPrivate(pOMD);
m_bOpenedThruThread = false;
}
}

这里需要注意，OpenMedia()调用了函数OpenMediaPrivate()。文件的打开功能实际上是在OpenMediaPrivate()中完成的。

下面我们来看看OpenMediaPrivate()的代码，发现比OpenMedia()要复杂很多。

//打开一个媒体（private）
bool CMainFrame::OpenMediaPrivate(CAutoPtr<OpenMediaData> pOMD)
{
//获得设置信息
CAppSettings& s = AfxGetAppSettings();

if (m_iMediaLoadState != MLS_CLOSED) {
ASSERT(0);
return false;
}
//OpenFileData
//OpenDVDData
//OpenDeviceData
//里面包含了文件或者DVD信息（名称等）
OpenFileData* pFileData = dynamic_cast<OpenFileData*>(pOMD.m_p);
OpenDVDData* pDVDData = dynamic_cast<OpenDVDData*>(pOMD.m_p);
OpenDeviceData* pDeviceData = dynamic_cast<OpenDeviceData*>(pOMD.m_p);
if (!pFileData && !pDVDData  && !pDeviceData) {
ASSERT(0);
return false;
}

// Clear DXVA state ...
ClearDXVAState();

#ifdef _DEBUG
// Debug trace code - Begin
// Check for bad / buggy auto loading file code
if (pFileData) {
POSITION pos = pFileData->fns.GetHeadPosition();
UINT index = 0;
while (pos != nullptr) {
CString path = pFileData->fns.GetNext(pos);
TRACE(_T("--> CMainFrame::OpenMediaPrivate - pFileData->fns[%d]:\n"), index);
TRACE(_T("\t%ws\n"), path.GetString()); // %ws - wide character string always
index++;
}
}
// Debug trace code - End
#endif

CString mi_fn = _T("");

if (pFileData) {
if (pFileData->fns.IsEmpty()) {
return false;
}

CString fn = pFileData->fns.GetHead();

int i = fn.Find(_T(":\\"));
if (i > 0) {
CString drive = fn.Left(i + 2);
UINT type = GetDriveType(drive);
CAtlList<CString> sl;
if (type == DRIVE_REMOVABLE || type == DRIVE_CDROM && GetCDROMType(drive[0], sl) != CDROM_Audio) {
int ret = IDRETRY;
while (ret == IDRETRY) {
WIN32_FIND_DATA findFileData;
HANDLE h = FindFirstFile(fn, &findFileData);
if (h != INVALID_HANDLE_VALUE) {
FindClose(h);
ret = IDOK;
} else {
CString msg;
msg.Format(IDS_MAINFRM_114, fn);
ret = AfxMessageBox(msg, MB_RETRYCANCEL);
}
}

if (ret != IDOK) {
return false;
}
}
mi_fn = fn;
}
}

SetLoadState(MLS_LOADING);

// FIXME: Don't show "Closed" initially
PostMessage(WM_KICKIDLE);

CString err;

m_fUpdateInfoBar = false;
BeginWaitCursor();

try {
CComPtr<IVMRMixerBitmap9>    pVMB;
CComPtr<IMFVideoMixerBitmap> pMFVMB;
CComPtr<IMadVRTextOsd>       pMVTO;
if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}

OpenCreateGraphObject(pOMD);

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}

SetupIViAudReg();

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}
//按类型的不同打开不同的文件
if (pFileData) {
//文件
OpenFile(pFileData);
} else if (pDVDData) {
//DVD
OpenDVD(pDVDData);
} else if (pDeviceData) {
if (s.iDefaultCaptureDevice == 1) {
HRESULT hr = OpenBDAGraph();
if (FAILED(hr)) {
throw (UINT)IDS_CAPTURE_ERROR_DEVICE;
}
} else {
OpenCapture(pDeviceData);
}
} else {
throw (UINT)IDS_INVALID_PARAMS_ERROR;
}

m_pCAP2 = nullptr;
m_pCAP = nullptr;
//查找接口
m_pGB->FindInterface(__uuidof(ISubPicAllocatorPresenter), (void**)&m_pCAP, TRUE);
m_pGB->FindInterface(__uuidof(ISubPicAllocatorPresenter2), (void**)&m_pCAP2, TRUE);
m_pGB->FindInterface(__uuidof(IVMRWindowlessControl9), (void**)&m_pVMRWC, FALSE); // might have IVMRMixerBitmap9, but not IVMRWindowlessControl9
m_pGB->FindInterface(__uuidof(IVMRMixerControl9), (void**)&m_pVMRMC, TRUE);
m_pGB->FindInterface(__uuidof(IVMRMixerBitmap9), (void**)&pVMB, TRUE);
m_pGB->FindInterface(__uuidof(IMFVideoMixerBitmap), (void**)&pMFVMB, TRUE);
pMVTO = m_pCAP;

if (s.fShowOSD || s.fShowDebugInfo) { // Force OSD on when the debug switch is used
if (pVMB) {
m_OSD.Start(m_pVideoWnd, pVMB, IsD3DFullScreenMode());
} else if (pMFVMB) {
m_OSD.Start(m_pVideoWnd, pMFVMB, IsD3DFullScreenMode());
} else if (pMVTO) {
m_OSD.Start(m_pVideoWnd, pMVTO);
}
}
//VMR9
SetupVMR9ColorControl();

// === EVR !
m_pGB->FindInterface(__uuidof(IMFVideoDisplayControl), (void**)&m_pMFVDC,  TRUE);
m_pGB->FindInterface(__uuidof(IMFVideoProcessor), (void**)&m_pMFVP, TRUE);
if (m_pMFVDC) {
m_pMFVDC->SetVideoWindow(m_pVideoWnd->m_hWnd);
}

//SetupEVRColorControl();
//does not work at this location
//need to choose the correct mode (IMFVideoProcessor::SetVideoProcessorMode)

BeginEnumFilters(m_pGB, pEF, pBF) {
if (m_pLN21 = pBF) {
m_pLN21->SetServiceState(s.fClosedCaptions ? AM_L21_CCSTATE_On : AM_L21_CCSTATE_Off);
break;
}
}
EndEnumFilters;

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}
//打开自定义的Graph
OpenCustomizeGraph();

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}
//设置视频窗口
OpenSetupVideo();

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}
//设置音量
OpenSetupAudio();

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}

if (m_pCAP && (!m_fAudioOnly || m_fRealMediaGraph)) {

if (s.fDisableInternalSubtitles) {
m_pSubStreams.RemoveAll(); // Needs to be replaced with code that checks for forced subtitles.
}

m_posFirstExtSub = nullptr;
POSITION pos = pOMD->subs.GetHeadPosition();
while (pos) {
LoadSubtitle(pOMD->subs.GetNext(pos), nullptr, true);
}
}

if (m_fOpeningAborted) {
throw (UINT)IDS_AG_ABORTED;
}
//设置视频窗口标题
OpenSetupWindowTitle(pOMD->title);

if (s.fEnableEDLEditor) {
m_wndEditListEditor.OpenFile(pOMD->title);
}

if (::GetCurrentThreadId() == AfxGetApp()->m_nThreadID) {
OnFilePostOpenmedia();
} else {
PostMessage(WM_COMMAND, ID_FILE_POST_OPENMEDIA);
}

while (m_iMediaLoadState != MLS_LOADED
&& m_iMediaLoadState != MLS_CLOSING // FIXME
) {
Sleep(50);
}
//设置音频流
DWORD audstm = SetupAudioStreams();
//设置字幕流
DWORD substm = SetupSubtitleStreams();

if (audstm) {
OnPlayAudio(ID_AUDIO_SUBITEM_START + audstm);
}
if (substm) {
SetSubtitle(substm - 1);
}

// PostMessage instead of SendMessage because the user might call CloseMedia and then we would deadlock

PostMessage(WM_COMMAND, ID_PLAY_PAUSE);

m_bFirstPlay = true;

if (!(s.nCLSwitches & CLSW_OPEN) && (s.nLoops > 0)) {
PostMessage(WM_COMMAND, ID_PLAY_PLAY);
} else {
// If we don't start playing immediately, we need to initialize
// the seekbar and the time counter.
OnTimer(TIMER_STREAMPOSPOLLER);
OnTimer(TIMER_STREAMPOSPOLLER2);
}

s.nCLSwitches &= ~CLSW_OPEN;

if (pFileData) {
if (pFileData->rtStart > 0) {
PostMessage(WM_RESUMEFROMSTATE, (WPARAM)PM_FILE, (LPARAM)(pFileData->rtStart / 10000));  // REFERENCE_TIME doesn't fit in LPARAM under a 32bit env.
}
} else if (pDVDData) {
if (pDVDData->pDvdState) {
PostMessage(WM_RESUMEFROMSTATE, (WPARAM)PM_DVD, (LPARAM)(CComPtr<IDvdState>(pDVDData->pDvdState).Detach()));    // must be released by the called message handler
}
} else if (pDeviceData) {
m_wndCaptureBar.m_capdlg.SetVideoInput(pDeviceData->vinput);
m_wndCaptureBar.m_capdlg.SetVideoChannel(pDeviceData->vchannel);
m_wndCaptureBar.m_capdlg.SetAudioInput(pDeviceData->ainput);
}
} catch (LPCTSTR msg) {
err = msg;
} catch (CString& msg) {
err = msg;
} catch (UINT msg) {
err.LoadString(msg);
}

EndWaitCursor();

if (!err.IsEmpty()) {
//关闭
CloseMediaPrivate();
m_closingmsg = err;

if (err != ResStr(IDS_AG_ABORTED)) {
if (pFileData) {
m_wndPlaylistBar.SetCurValid(false);

if (m_wndPlaylistBar.IsAtEnd()) {
m_nLoops++;
}

if (s.fLoopForever || m_nLoops < s.nLoops) {
bool hasValidFile = false;

if (m_nLastSkipDirection == ID_NAVIGATE_SKIPBACK) {
hasValidFile = m_wndPlaylistBar.SetPrev();
} else {
hasValidFile = m_wndPlaylistBar.SetNext();
}

if (hasValidFile) {
OpenCurPlaylistItem();
}
} else if (m_wndPlaylistBar.GetCount() > 1) {
DoAfterPlaybackEvent();
}
} else {
OnNavigateSkip(ID_NAVIGATE_SKIPFORWARD);
}
}
} else {
m_wndPlaylistBar.SetCurValid(true);

// Apply command line audio shift
if (s.rtShift != 0) {
SetAudioDelay(s.rtShift);
s.rtShift = 0;
}
}

m_nLastSkipDirection = 0;

if (s.AutoChangeFullscrRes.bEnabled && (m_fFullScreen || IsD3DFullScreenMode())) {
AutoChangeMonitorMode();
}
if (m_fFullScreen && s.fRememberZoomLevel) {
m_fFirstFSAfterLaunchOnFS = true;
}

m_LastOpenFile = pOMD->title;

PostMessage(WM_KICKIDLE); // calls main thread to update things

if (!m_bIsBDPlay) {
m_MPLSPlaylist.RemoveAll();
m_LastOpenBDPath = _T("");
}
m_bIsBDPlay = false;

return err.IsEmpty();
}

这里需要注意，根据打开方式的不同，OpenMediaPrivate()调用了不同的函数。

如果输入的类型为文件，则调用OpenFile()

如果输入的类型为DVD，则调用OpenDVD()

如果输入的类型为设备（例如摄像头），则调用OpenCapture()

在这里，我们假设输入的类型为文件（实际上这也是最普遍的情况）。

看看OpenFile()的源代码。

//打开文件
void CMainFrame::OpenFile(OpenFileData* pOFD)
{
if (pOFD->fns.IsEmpty()) {
throw (UINT)IDS_MAINFRM_81;
}
//获取设置
CAppSettings& s = AfxGetAppSettings();

bool bMainFile = true;

POSITION pos = pOFD->fns.GetHeadPosition();
while (pos) {
CString fn = pOFD->fns.GetNext(pos);

fn.Trim();
if (fn.IsEmpty() && !bMainFile) {
break;
}
//使用DirectShow播放文件
HRESULT hr = m_pGB->RenderFile(CStringW(fn), nullptr);

if (bMainFile) {
// Don't try to save file position if source isn't seekable
REFERENCE_TIME rtDur = 0;
m_pMS->GetDuration(&rtDur);

m_bRememberFilePos = s.fKeepHistory && s.fRememberFilePos && rtDur > 0;

if (m_bRememberFilePos && !s.filePositions.AddEntry(fn)) {
REFERENCE_TIME rtPos = s.filePositions.GetLatestEntry()->llPosition;
if (m_pMS) {
m_pMS->SetPositions(&rtPos, AM_SEEKING_AbsolutePositioning, nullptr, AM_SEEKING_NoPositioning);
}
}
}
QueryPerformanceCounter(&m_liLastSaveTime);

if (FAILED(hr)) {
if (bMainFile) {
if (s.fReportFailedPins) {
CComQIPtr<IGraphBuilderDeadEnd> pGBDE = m_pGB;
if (pGBDE && pGBDE->GetCount()) {
CMediaTypesDlg(pGBDE, GetModalParent()).DoModal();
}
}

UINT err;

switch (hr) {
case E_ABORT:
case RFS_E_ABORT:
err = IDS_MAINFRM_82;
break;
case E_FAIL:
case E_POINTER:
default:
err = IDS_MAINFRM_83;
break;
case E_INVALIDARG:
err = IDS_MAINFRM_84;
break;
case E_OUTOFMEMORY:
err = IDS_AG_OUT_OF_MEMORY;
break;
case VFW_E_CANNOT_CONNECT:
err = IDS_MAINFRM_86;
break;
case VFW_E_CANNOT_LOAD_SOURCE_FILTER:
err = IDS_MAINFRM_87;
break;
case VFW_E_CANNOT_RENDER:
err = IDS_MAINFRM_88;
break;
case VFW_E_INVALID_FILE_FORMAT:
err = IDS_MAINFRM_89;
break;
case VFW_E_NOT_FOUND:
err = IDS_MAINFRM_90;
break;
case VFW_E_UNKNOWN_FILE_TYPE:
err = IDS_MAINFRM_91;
break;
case VFW_E_UNSUPPORTED_STREAM:
err = IDS_MAINFRM_92;
break;
case RFS_E_NO_FILES:
err = IDS_RFS_NO_FILES;
break;
case RFS_E_COMPRESSED:
err = IDS_RFS_COMPRESSED;
break;
case RFS_E_ENCRYPTED:
err = IDS_RFS_ENCRYPTED;
break;
case RFS_E_MISSING_VOLS:
err = IDS_RFS_MISSING_VOLS;
break;
}

throw err;
}
}

// We don't keep track of the standard input since that hardly makes any sense
if (s.fKeepHistory && fn != _T("pipe:0")) {
CRecentFileList* pMRU = bMainFile ? &s.MRU : &s.MRUDub;
pMRU->ReadList();
pMRU->Add(fn);
pMRU->WriteList();
SHAddToRecentDocs(SHARD_PATH, fn);
}

if (bMainFile) {
pOFD->title = fn;
}

bMainFile = false;

if (m_fCustomGraph) {
break;
}
}

if (s.fReportFailedPins) {
CComQIPtr<IGraphBuilderDeadEnd> pGBDE = m_pGB;
if (pGBDE && pGBDE->GetCount()) {
CMediaTypesDlg(pGBDE, GetModalParent()).DoModal();
}
}

if (!(m_pAMOP = m_pGB)) {
BeginEnumFilters(m_pGB, pEF, pBF);
if (m_pAMOP = pBF) {
break;
}
EndEnumFilters;
}

if (FindFilter(CLSID_MPCShoutcastSource, m_pGB)) {
m_fUpdateInfoBar = true;
}

SetupChapters();

CComQIPtr<IKeyFrameInfo> pKFI;
BeginEnumFilters(m_pGB, pEF, pBF);
if (pKFI = pBF) {
break;
}
EndEnumFilters;
UINT nKFs = 0;
if (pKFI && S_OK == pKFI->GetKeyFrameCount(nKFs) && nKFs > 0) {
UINT k = nKFs;
if (!m_kfs.SetCount(k) || S_OK != pKFI->GetKeyFrames(&TIME_FORMAT_MEDIA_TIME, m_kfs.GetData(), k) || k != nKFs) {
m_kfs.RemoveAll();
}
}
//设置播放模式
SetPlaybackMode(PM_FILE);
}

从OpenFile()函数的源代码我们可以看出，mpc-hc调用了DirectShow的函数，打开相应的文件。比如说：

HRESULT hr = m_pGB->RenderFile(CStringW(fn), nullptr);