c++ - DecideBufferSize值似乎被忽略

我有一个问题，当使用网络摄像头作为源时，输入示例大于分配器提供的缓冲区大小，如您在此代码的ASSERT语句中所见。

HRESULT MCMyOutputPin::Deliver(IMediaSample* sample)
{
    HRESULT hr = NO_ERROR;
    myLogger->LogDebug("In Outputpin Deliver", L"D:\\TEMP\\yc.log");
    if (sample->GetActualDataLength() > 0)
    {
        IMediaSample *outsample;



        hr = m_pAllocator->GetBuffer(&outsample, NULL, NULL, NULL);
        if (FAILED(hr))
        {
            return hr;
        }
        BYTE* sampleBuffer = NULL;
        BYTE*  newBuffer = NULL;
        long ulDataLen = sample->GetSize();
        long datalenout = outsample->GetSize(); //this is always 92160
        outsample->GetPointer(&newBuffer);
        ASSERT(datalenout >= ulDataLen); //This fails
        memcpy((void *)newBuffer, (void *)sampleBuffer, ulDataLen);


        m_pInputPin->Receive(outsample);

        outsample->Release();
        sample->Release();




    }

    return hr;
    //Forward to filter
}

因此memcpy肯定会失败，因为您无法将某些内容复制到小于数据的缓冲区中。
所以我尝试在DecideBufferSize中调整buffersize:

HRESULT MCMyOutputPin::DecideBufferSize(IMemAllocator *pAlloc, ALLOCATOR_PROPERTIES *pProps)
{
    myLogger->LogDebug("On DecideBufferSIze", L"D:\\TEMP\\yc.log");
    ALLOCATOR_PROPERTIES    act;
    HRESULT                 hr;

    // by default we do something like this...
    pProps->cbAlign     = 1;
    pProps->cBuffers = 30;
    long buffersize = this->CurrentMediaType().lSampleSize * 3;
    pProps->cbBuffer = 10 * 10 * 1000;
    pProps->cbPrefix    = 0;

    hr = pAlloc->SetProperties(pProps, &act);
    if (FAILED(hr)) return hr;

    // make sure the allocator is OK with it.
    if ((pProps->cBuffers > act.cBuffers)  ||
        (pProps->cbBuffer > act.cbBuffer) ||
        (pProps->cbAlign > act.cbAlign))
        return E_FAIL;

    return NOERROR;
}

被忽略。定位器返回的样本大小始终为92160。

我还确保实际调用DecideBufferSize方法。

如何设置Allocator-> GetBuffer()返回的Buffer的大小？

最佳答案

MSDN states it相当准确:



缓冲区大小的决定是协商的问题。您的设置要求并不意味着将被接受。



92160到底有什么问题，是什么让您认为它无效？您正在寻找错误问题的答案。如果您拥有分配器，则可以设置其缓冲区大小。如果您不拥有和管理它，那么您必须以已经拥有的规模生活。

我给了您MSDN链接a few question ago，它解释了为什么增大大小的缓冲区有时有效，甚至更有效-它们是不可避免的。