Question

我正在探索Windows媒体基金会我想在一个窗口中混合并显示两个视频流我正在关注MS提供的一些样本。

我正在尝试向拓扑添加多个媒体源，我想将两个媒体文件添加到拓扑中。

根据以下链接，我按照代码添加拓扑中的媒体源：
https://msdn.microsoft.com/en-us/library/windows/desktop/ms701605(v=vs.85).aspx

以下是将源节点添加到拓扑中的代码：

HRESULT hr = pPD->GetStreamDescriptorByIndex(iStream, &fSelected, &pSD);
if (FAILED(hr))
{
    goto done;
}

if (fSelected)
{
    // Create the media sink activation object.
    hr = CreateMediaSinkActivate(pSD, hVideoWnd, &pSinkActivate);
    if (FAILED(hr))
    {
        goto done;
    }

    // Add a source node for this stream.
    hr = AddSourceNode(pTopology, pSource, pPD, pSD, &pSourceNode);
    if (FAILED(hr))
    {
        goto done;
    }

    // Create the output node for the renderer.
    hr = AddOutputNode(pTopology, pSinkActivate, 0, &pOutputNode);
    if (FAILED(hr))
    {
        goto done;
    }

    // Connect the source node to the output node.
    hr = pSourceNode->ConnectOutput(0, pOutputNode, 0);
}

但我无法在拓扑中添加多个媒体源我的单个文件播放工作正常，但我无法混合和显示两个文件。

Answer 1

I recommend split your task on five step: 1. write code for playing ONE video file. On MSDN there is example code: How to Play Media Files with Media Foundation. 2. research code of WORKABLE player for point, where created MediaSource from video file path(URL). 3. create TWO MediaSource from two video file paths(URL). 4. by function MFCreateAggregateSource create from TWO MediaSource - ONE MediaSource and retuurn MediaSource from method player HRESULT CreateMediaSource(PCWSTR sURL, IMFMediaSource **ppSource) 5. call 'hr = AddOutputNode(pTopology, pSinkActivate, 0, &pOutputNode);' twice: 'hr = AddOutputNode(pTopology, pSinkActivate, 0, &pOutputNode);' for first video stream and hr = AddOutputNode(pTopology, pSinkActivate, 1, &pOutputNode); for second video stream.

Regards.

P.S. If you will use two video with audio streams, then You will have FOUR streams in Aggregate MediaSource - it could need FIND the stream ID for video stream. P.S.S It is not easy recommend from viewing only demo code, but in CreateMediaSinkActivate you will find code hr = MFCreateVideoRendererActivate(hVideoWindow, &pActivate);. In your code, you must create this Activate before:

// For each stream, create the topology nodes and add them to the topology.
for (DWORD i = 0; i < cSourceStreams; i++)
{
    hr = AddBranchToPartialTopology(pTopology, pSource, pPD, i, hVideoWnd);
    if (FAILED(hr))
    {
        goto done;
    }
}

then set this crated Activate as argument for AddBranchToPartialTopology

for example:

hr = MFCreateVideoRendererActivate(hVideoWindow, &pVideoRendererActivate);
// For each stream, create the topology nodes and add them to the topology.
for (DWORD i = 0; i < cSourceStreams; i++)
{
    hr = AddBranchToPartialTopology(pTopology, pSource, pPD, i, pVideoRendererActivate);
    if (FAILED(hr))
    {
        goto done;
    }
}

In AddBranchToPartialTopologyyou must write something like this:

HRESULT AddBranchToPartialTopology(
IMFTopology *pTopology,         // Topology.
IMFMediaSource *pSource,        // Media source.
IMFPresentationDescriptor *pPD, // Presentation descriptor.
DWORD iStream,                  // Stream index.
IMFActivate* aVideoRendererActivate)                 // VideoRenderer for video playback.
{
IMFStreamDescriptor *pSD = NULL;
IMFActivate         *pSinkActivate = NULL;
IMFTopologyNode     *pSourceNode = NULL;
IMFTopologyNode     *pOutputNode = NULL;

BOOL fSelected = FALSE;

HRESULT hr = pPD->GetStreamDescriptorByIndex(iStream, &fSelected, &pSD);
if (FAILED(hr))
{
    goto done;
}

DWORD iStreamID = 0;

if (fSelected)
{
    // Create the media sink activation object.
    hr = CreateMediaSinkActivate(pSD, iStreamID, aVideoRendererActivate, &pSinkActivate);

In 'CreateMediaSinkActivate' you must write something like this:

DWORD globalVideoIndex = 0;

HRESULT CreateMediaSinkActivate(
IMFStreamDescriptor *pSourceSD,     // Pointer to the stream descriptor.
DWORD& iStreamID, // ctream index
IMFActivate *pVideoRendererActivate,                  // Handle to the video      renderer activate.
IMFActivate **ppActivate
)
{
IMFMediaTypeHandler *pHandler = NULL;
IMFActivate *pActivate = NULL;

// Get the media type handler for the stream.
HRESULT hr = pSourceSD->GetMediaTypeHandler(&pHandler);
if (FAILED(hr))
{
    goto done;
}

// Get the major media type.
GUID guidMajorType;
hr = pHandler->GetMajorType(&guidMajorType);
if (FAILED(hr))
{
    goto done;
}

// Create an IMFActivate object for the renderer, based on the media type.
if (MFMediaType_Audio == guidMajorType)
{
    // Create the audio renderer.
    hr = MFCreateAudioRendererActivate(&pActivate);
}
else if (MFMediaType_Video == guidMajorType)
{
    // Share the video renderer.

    hr = pVideoRendererActivate->QueryInterface(IID_PPV_ARG(pActivate))

    iStreamID = globalVideoIndex++;
}
else
{
    // Unknown stream type. 
    hr = E_FAIL;
    // Optionally, you could deselect this stream instead of failing.
}
if (FAILED(hr))
{
    goto done;
}

// Return IMFActivate pointer to caller.
*ppActivate = pActivate;
(*ppActivate)->AddRef();

done:
SafeRelease(&pHandler);
SafeRelease(&pActivate);
return hr;
}

In AddBranchToPartialTopology you must write:

// Create the output node for the renderer.
hr = AddOutputNode(pTopology, pSinkActivate, iStreamID, &pOutputNode);
if (FAILED(hr))
{
    goto done;
}

for Audio streams iStreamID will zero, but for video stream it will increment from global variable globalVideoIndex.

Idea is that code create Activate for video renderer BEFORE create Topology - it is OK. Then this ONE video renderer activate share by ref pointer between ALL video streams in MediaSource by checking condition if (MFMediaType_Video == guidMajorType). Each VIDEO stream has got unique id from 0 by incrementing global variable globalVideoIndex++ - this id set in method hr = AddOutputNode(pTopology, pSinkActivate, iStreamID, &pOutputNode);. As a result, all video streams will be drawn by ONE video renderer, and video stream with iStreamID is 0 will reference background, while other video streams will additional.

在拓扑和显示混合视频中添加两个媒体源 - Windows Media Foundation

1 个答案: