我是 DirectShow 的新手，正在向我的应用程序添加视频流。我研究了很多解决方案(TouchLess、DirectShow.net 等)，最终选择了这个 small project on Code Project 没有太多东西，这就是我选择它的原因；我想要一个小的代码库来使用，因为我需要快速实现这个功能。
经过一整天的阅读、试验和调试，我终于让一切正常运行。有一个延迟，这是一个无赖，但我可以稍后再担心。此时我遇到的问题是 the camera is capable of 1280X720 并且我想使用此分辨率。然而，它似乎决心以 640x480 进行捕获。随着我越来越深入地学习如何设置分辨率，我终于想我已经弄清楚了。我还在代码项目页面的评论中找到了作为基础的代码。
经过 6 个小时的尝试，我无法让这台相机更改其分辨率。我没有收到任何错误，从 SetFormat() 返回的 HRESULT 为 0，但相机不会改变分辨率。
粘贴所有内容的代码太多，但我想包括构建图表的部分，因为我认为这就是问题所在。
这是设置图形的代码
void CameraMethods::StartCamera(int camIndex, interior_ptr<int> width,
interior_ptr<int> height)
{
if (g_pGraphBuilder != NULL)
throw gcnew ArgumentException("Graph Builder was null");
IMoniker *pMoniker = GetMoniker(camIndex);
pMoniker->AddRef();
HRESULT hr = S_OK;
// Build all the necessary interfaces to start the capture
if (SUCCEEDED(hr))
{
hr = CoCreateInstance(CLSID_FilterGraph,
NULL,
CLSCTX_INPROC,
IID_IGraphBuilder,
(LPVOID*)&g_pGraphBuilder);
}
if (SUCCEEDED(hr))
hr = g_pGraphBuilder->QueryInterface(IID_IMediaControl, (LPVOID*)&g_pMediaControl);
if (SUCCEEDED(hr))
{
hr = CoCreateInstance(CLSID_CaptureGraphBuilder2,
NULL,
CLSCTX_INPROC,
IID_ICaptureGraphBuilder2,
(LPVOID*)&g_pCaptureGraphBuilder);
}
// Setup the filter graph
if (SUCCEEDED(hr))
hr = g_pCaptureGraphBuilder->SetFiltergraph(g_pGraphBuilder);
// Build the camera from the moniker
if (SUCCEEDED(hr))
hr = pMoniker->BindToObject(NULL, NULL, IID_IBaseFilter, (LPVOID*)&g_pIBaseFilterCam);
// Add the camera to the filter graph
if (SUCCEEDED(hr))
hr = g_pGraphBuilder->AddFilter(g_pIBaseFilterCam, L"WebCam");
// Create a SampleGrabber
if (SUCCEEDED(hr))
hr = CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter,
(void**)&g_pIBaseFilterSampleGrabber);
// Configure the Sample Grabber
if (SUCCEEDED(hr))
hr = ConfigureSampleGrabber(g_pIBaseFilterSampleGrabber);
// Set the resolution - I have NO idea where this should be executed
SetCaptureFormat(camIndex, *width, *height);
// Add Sample Grabber to the filter graph
if (SUCCEEDED(hr))
hr = g_pGraphBuilder->AddFilter(g_pIBaseFilterSampleGrabber, L"SampleGrabber");
// Create the NullRender
if (SUCCEEDED(hr))
hr = CoCreateInstance(CLSID_NullRenderer, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter,
(void**)&g_pIBaseFilterNullRenderer);
// Add the Null Render to the filter graph
if (SUCCEEDED(hr))
hr = g_pGraphBuilder->AddFilter(g_pIBaseFilterNullRenderer, L"NullRenderer");
// Configure the render stream
if (SUCCEEDED(hr))
hr = g_pCaptureGraphBuilder->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,
g_pIBaseFilterCam, g_pIBaseFilterSampleGrabber, g_pIBaseFilterNullRenderer);
// Grab the capture width and height
if (SUCCEEDED(hr))
{
ISampleGrabber* pGrabber = NULL;
hr = g_pIBaseFilterSampleGrabber->QueryInterface(IID_ISampleGrabber, (LPVOID*)&pGrabber);
if (SUCCEEDED(hr))
{
AM_MEDIA_TYPE mt;
hr = pGrabber->GetConnectedMediaType(&mt);
if (SUCCEEDED(hr))
{
VIDEOINFOHEADER *pVih;
if ((mt.formattype == FORMAT_VideoInfo) &&
(mt.cbFormat >= sizeof(VIDEOINFOHEADER)) &&
(mt.pbFormat != NULL) )
{
pVih = (VIDEOINFOHEADER*)mt.pbFormat;
*width = pVih->bmiHeader.biWidth;
*height = pVih->bmiHeader.biHeight;
}
else
{
hr = E_FAIL; // Wrong format
}
// FreeMediaType(mt); (from MSDN)
if (mt.cbFormat != 0)
{
CoTaskMemFree((PVOID)mt.pbFormat);
mt.cbFormat = 0;
mt.pbFormat = NULL;
}
if (mt.pUnk != NULL)
{
// Unecessary because pUnk should not be used, but safest.
mt.pUnk->Release();
mt.pUnk = NULL;
}
}
}
if (pGrabber != NULL)
{
pGrabber->Release();
pGrabber = NULL;
}
}
// Start the capture
if (SUCCEEDED(hr))
hr = g_pMediaControl->Run();
// If init fails then ensure that you cleanup
if (FAILED(hr))
StopCamera();
else
hr = S_OK; // Make sure we return S_OK for success
// Cleanup
if (pMoniker != NULL)
{
pMoniker->Release();
pMoniker = NULL;
}
if (SUCCEEDED(hr))
this->activeCameraIndex = camIndex;
else
throw gcnew COMException("Error Starting Camera", hr);
}
[更新] 在 下面添加了 ConfigureSampleGrabber() 方法
HRESULT CameraMethods::ConfigureSampleGrabber(IBaseFilter *pIBaseFilter)
{
HRESULT hr = S_OK;
ISampleGrabber *pGrabber = NULL;
hr = pIBaseFilter->QueryInterface(IID_ISampleGrabber, (void**)&pGrabber);
if (SUCCEEDED(hr))
{
AM_MEDIA_TYPE mt;
ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24;
mt.formattype = FORMAT_VideoInfo;
hr = pGrabber->SetMediaType(&mt);
}
if (SUCCEEDED(hr))
hr = pGrabber->SetCallback(new SampleGrabberCB(), 1);
if (pGrabber != NULL)
{
pGrabber->Release();
pGrabber = NULL;
}
return hr;
}
这几乎是来自 CodeProject 源代码的确切代码。然后我添加了这个方法来设置分辨率:
void CameraMethods::SetCaptureFormat(int camIndex, int width, int height)
{
HRESULT hr = S_OK;
IMoniker* pMoniker = GetMoniker(camIndex);
IBaseFilter* pCap;
hr=pMoniker->BindToObject(0,0,IID_IBaseFilter,(void **)&pCap);
if(!SUCCEEDED(hr))
return;
IAMStreamConfig *pConfig = NULL;
if(g_pCaptureGraphBuilder == NULL) // no CaptureGraphBuilder initialised
return;
hr = g_pCaptureGraphBuilder->FindInterface(
&PIN_CATEGORY_CAPTURE, // Preview pin.
0, // Any media type.
pCap, // Pointer to the capture filter.
IID_IAMStreamConfig, (void**)&pConfig);
if(!SUCCEEDED(hr))
return;
int iCount = 0, iSize = 0;
hr = pConfig->GetNumberOfCapabilities(&iCount, &iSize);
// Check the size to make sure we pass in the correct structure.
if (iSize == sizeof(VIDEO_STREAM_CONFIG_CAPS)) {
// Use the video capabilities structure.
for (int iFormat = 0; iFormat < iCount; iFormat++)
{
VIDEO_STREAM_CONFIG_CAPS scc;
AM_MEDIA_TYPE *pmt;
/* Note: Use of the VIDEO_STREAM_CONFIG_CAPS structure to configure a video device is
deprecated. Although the caller must allocate the buffer, it should ignore the
contents after the method returns. The capture device will return its supported
formats through the pmt parameter. */
hr = pConfig->GetStreamCaps(iFormat, &pmt, (BYTE*)&scc);
if (SUCCEEDED(hr))
{
/* Examine the format, and possibly use it. */
if (pmt->formattype == FORMAT_VideoInfo) {
// Check the buffer size.
if (pmt->cbFormat >= sizeof(VIDEOINFOHEADER))
{
VIDEOINFOHEADER *pVih = reinterpret_cast<VIDEOINFOHEADER*>(pmt->pbFormat);
BITMAPINFOHEADER *bmiHeader = &pVih->bmiHeader;
/* Access VIDEOINFOHEADER members through pVih. */
if( bmiHeader->biWidth == width && bmiHeader->biHeight == height &&
bmiHeader->biBitCount == 24)
{
hr = pConfig->SetFormat(pmt);
}
}
}
// Delete the media type when you are done.
DeleteMediaType(pmt);
}
}
}
}
我已逐步完成代码并验证对 SetFormat() 的调用已执行并返回有效的 HRESULT。但是，捕获的帧没有变化。
如果没有错误消息，很难知道从哪里开始。我希望这里有一些 DirectShow 专家会看到这个问题，我什至对一个很好的时尚居高临下感到满意“好吧，一旦缓冲区分配到过滤器堆栈和小部件初始化为 foobar!Pft...大声笑”;)
教教我哦，DirectShow/COM 大神!
[更新 #2](仅供引用，奇怪的是我们不能只向该系统添加新消息并需要像这样编辑原始消息)
根据 Roman 的建议，我使用 GraphStudio 来查看我的图表。我承认我仍然不明白我在看什么。我发现了一个“文本报告”功能，并认为在此处发布该报告会有所帮助，以防它显示一些有值(value)的信息。
--------------------------------------------------
Filters
--------------------------------------------------
1. Smart Tee
2. MJPEG Decompressor
3. SampleGrabber
4. NullRenderer
5. WebCam
--------------------------------------------------
Connections
--------------------------------------------------
1. [Smart Tee]/(Capture) -> [MJPEG Decompressor]/(XForm In)
Major: MEDIATYPE_Video
Subtype: MEDIASUBTYPE_MJPG
bFixedSizeSamples: TRUE
bTemporalCompression: FALSE
lSampleSize: 921600
cbFormat: 88
Format: FORMAT_VideoInfo
VIDEOINFOHEADER:
rcSource: (0,0,0,0)
rcTarget: (0,0,0,0)
dwBitRate: 221184000
dwBitErrorRate: 0
AvgTimePerFrame: 333333
BITMAPINFOHEADER:
biSize: 40
biWidth: 640
biHeight: 480
biPlanes: 1
biBitCount: 24
biCompression: 0x47504A4D
biSizeImage: 921600
biXPelsPerMeter: 0
biYPelsPerMeter: 0
biClrUsed: 0
biClrImportant: 0
2. [MJPEG Decompressor]/(XForm Out) -> [SampleGrabber]/(Input)
Major: MEDIATYPE_Video
Subtype: MEDIASUBTYPE_RGB24
bFixedSizeSamples: TRUE
bTemporalCompression: FALSE
lSampleSize: 921600
cbFormat: 88
Format: FORMAT_VideoInfo
VIDEOINFOHEADER:
rcSource: (0,0,0,0)
rcTarget: (0,0,0,0)
dwBitRate: 221184221
dwBitErrorRate: 0
AvgTimePerFrame: 333333
BITMAPINFOHEADER:
biSize: 40
biWidth: 640
biHeight: 480
biPlanes: 1
biBitCount: 24
biCompression: 0x00000000
biSizeImage: 921600
biXPelsPerMeter: 0
biYPelsPerMeter: 0
biClrUsed: 0
biClrImportant: 0
3. [SampleGrabber]/(Output) -> [NullRenderer]/(In)
Major: MEDIATYPE_Video
Subtype: MEDIASUBTYPE_RGB24
bFixedSizeSamples: TRUE
bTemporalCompression: FALSE
lSampleSize: 921600
cbFormat: 88
Format: FORMAT_VideoInfo
VIDEOINFOHEADER:
rcSource: (0,0,0,0)
rcTarget: (0,0,0,0)
dwBitRate: 221184221
dwBitErrorRate: 0
AvgTimePerFrame: 333333
BITMAPINFOHEADER:
biSize: 40
biWidth: 640
biHeight: 480
biPlanes: 1
biBitCount: 24
biCompression: 0x00000000
biSizeImage: 921600
biXPelsPerMeter: 0
biYPelsPerMeter: 0
biClrUsed: 0
biClrImportant: 0
4. [WebCam]/(Capture) -> [Smart Tee]/(Input)
Major: MEDIATYPE_Video
Subtype: MEDIASUBTYPE_MJPG
bFixedSizeSamples: TRUE
bTemporalCompression: FALSE
lSampleSize: 921600
cbFormat: 88
Format: FORMAT_VideoInfo
VIDEOINFOHEADER:
rcSource: (0,0,0,0)
rcTarget: (0,0,0,0)
dwBitRate: 221184000
dwBitErrorRate: 0
AvgTimePerFrame: 333333
BITMAPINFOHEADER:
biSize: 40
biWidth: 640
biHeight: 480
biPlanes: 1
biBitCount: 24
biCompression: 0x47504A4D
biSizeImage: 921600
biXPelsPerMeter: 0
biYPelsPerMeter: 0
biClrUsed: 0
biClrImportant: 0
[更新 #3] - 天哪，我开始了什么？!
为什么在我 came across something that supports Roman 的色彩空间不匹配理论之前，谷歌搜索比我搜索的更深入。我 downloaded the app 并且马上不得不修复一个缓冲区太小的错误。解决后，我能够生成以下报告:
Dump Version: 1.2
Using device: Microsoft® LifeCam Studio(TM)
Interface: USB
Pin Name: Capture
Pin direction: Output
Pin category: Capture
IAMVideoCompression: No
ISpecifyPropertyPages: Yes
IMediaSeeking: Yes
IPinConnection: No
IPinFlowControl: No
IAMDroppedFrames: No
IAMVideoProcAmp: No
IAMVideoControlCaps: 0
Major Type Sub Type Format Type FixedSamples Temporal Compression Sample Size Max Input Size Min Output Size Max Output Size Min-Max FPS Video Standard
Video YUY2 VideoInfo Fixed NotTemporal 614400 640x480 640x480 640x480 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 614400 640x480 640x480 640x480 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 1843200 1280x720 1280x720 1280x720 7.50-10.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 1843200 1280x720 1280x720 1280x720 7.50-10.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 1044480 960x544 960x544 960x544 7.50-20.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 1044480 960x544 960x544 960x544 7.50-20.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 716800 800x448 800x448 800x448 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 716800 800x448 800x448 800x448 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 460800 640x360 640x360 640x360 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 460800 640x360 640x360 640x360 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 203520 424x240 424x240 424x240 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 203520 424x240 424x240 424x240 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 202752 352x288 352x288 352x288 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 202752 352x288 352x288 352x288 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 153600 320x240 320x240 320x240 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 153600 320x240 320x240 320x240 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 960000 800x600 800x600 800x600 7.50-20.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 960000 800x600 800x600 800x600 7.50-20.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 50688 176x144 176x144 176x144 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 50688 176x144 176x144 176x144 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 38400 160x120 160x120 160x120 7.50-30.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 38400 160x120 160x120 160x120 7.50-30.00 {none}
Video YUY2 VideoInfo Fixed NotTemporal 4147200 1920x1080 1920x1080 1920x1080 5.00-5.00 {none}
Video YUY2 VideoInfo2 Fixed NotTemporal 4147200 1920x1080 1920x1080 1920x1080 5.00-5.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 921600 640x480 640x480 640x480 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 921600 640x480 640x480 640x480 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 6220800 1920x1080 1920x1080 1920x1080 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 6220800 1920x1080 1920x1080 1920x1080 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 2764800 1280x720 1280x720 1280x720 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 2764800 1280x720 1280x720 1280x720 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 1566720 960x544 960x544 960x544 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 1566720 960x544 960x544 960x544 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 1075200 800x448 800x448 800x448 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 1075200 800x448 800x448 800x448 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 691200 640x360 640x360 640x360 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 691200 640x360 640x360 640x360 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 1440000 800x600 800x600 800x600 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 1440000 800x600 800x600 800x600 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 311040 432x240 432x240 432x240 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 311040 432x240 432x240 432x240 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 304128 352x288 352x288 352x288 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 304128 352x288 352x288 352x288 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 76032 176x144 176x144 176x144 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 76032 176x144 176x144 176x144 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 230400 320x240 320x240 320x240 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 230400 320x240 320x240 320x240 7.50-30.00 {none}
Video MJPG VideoInfo Fixed NotTemporal 57600 160x120 160x120 160x120 7.50-30.00 {none}
Video MJPG VideoInfo2 Fixed NotTemporal 57600 160x120 160x120 160x120 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 460800 640x480 640x480 640x480 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 460800 640x480 640x480 640x480 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 1382400 1280x720 1280x720 1280x720 7.50-15.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 1382400 1280x720 1280x720 1280x720 7.50-15.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 783360 960x544 960x544 960x544 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 783360 960x544 960x544 960x544 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 537600 800x448 800x448 800x448 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 537600 800x448 800x448 800x448 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 345600 640x360 640x360 640x360 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 345600 640x360 640x360 640x360 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 152640 424x240 424x240 424x240 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 152640 424x240 424x240 424x240 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 152064 352x288 352x288 352x288 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 152064 352x288 352x288 352x288 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 115200 320x240 320x240 320x240 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 115200 320x240 320x240 320x240 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 720000 800x600 800x600 800x600 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 720000 800x600 800x600 800x600 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 38016 176x144 176x144 176x144 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 38016 176x144 176x144 176x144 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 28800 160x120 160x120 160x120 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 28800 160x120 160x120 160x120 7.50-30.00 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo Fixed NotTemporal 3110400 1920x1080 1920x1080 1920x1080 7.50-7.50 {none}
Video {3032344D-0000-0010-8000-00AA00389B71} VideoInfo2 Fixed NotTemporal 3110400 1920x1080 1920x1080 1920x1080 7.50-7.50 {none}
Pin Name: Video Camera Terminal
Pin direction: Input
Pin category: {3EBC7959-3310-493B-AA81-C7E132D56F71}
IAMVideoCompression: No
ISpecifyPropertyPages: Yes
IMediaSeeking: No
IPinConnection: No
IPinFlowControl: No
IAMDroppedFrames: No
IAMVideoProcAmp: No
IAMVideoControlCaps: 0
Major Type Sub Type Format Type FixedSamples Temporal Compression Sample Size
最佳答案
您将它放在正确的位置 - 在 AddFilter 已经在图形中之后，但在其输出引脚连接之前。如果您的 HRESULT 成功，那么您可能期望更改格式，但可能会有异常(exception)，例如下游过滤器不接受此媒体类型，他们从一开始就开始协商。
您没有在此处显示您的 ConfigureSampleGrabber，因此可能是您想要的这种媒体类型不被用于制作过滤器图的样本采集器接受以尝试替代媒体类型和/或中间过滤器(例如解码器)。
您实际上可以做一些事情。
希望这可以帮助。
关于directshow - 无法使 IAMStreamConfig.SetFormat() 与 LifeCam Studio 一起使用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7383372/