Manage DeckLink cards' footprint

Hi,

As anyone successfully managed the footprint size that a DeckLink board occupies in the RAM?
Eg. If I'm recording PAL signals, I don't need support for 4k, so the extra buffer space is to be avoided.

If you are using the low level API create you own BMDAllocator and use SetVideoOutputFrameMemoryAllocator or SetVideoInputFrameMemoryAllocator ... and you decide how many buffers you will allow to be used

Thanks for the response,

I'm using, as BMDAllocator, a ripped version of BMD's LoopThroughWithOpenGLCompositing sample.
But I don't think I can control the allocated buffer.

Code follows:

Code: Select all

DeckLinkMemoryAllocator::DeckLinkMemoryAllocator(unsigned cacheSize) :
mRefCount(1),
mFrameCacheSize(cacheSize)      // large cache size will keep more memory pinned and may result in out of memory errors
{
}

DeckLinkMemoryAllocator::~DeckLinkMemoryAllocator()
{
}

// IUnknown methods
HRESULT STDMETHODCALLTYPE   DeckLinkMemoryAllocator::QueryInterface(REFIID /*iid*/, LPVOID* /*ppv*/)
{
    return E_NOTIMPL;
}

ULONG STDMETHODCALLTYPE      DeckLinkMemoryAllocator::AddRef(void)
{
    return InterlockedIncrement(&mRefCount);
}

ULONG STDMETHODCALLTYPE      DeckLinkMemoryAllocator::Release(void)
{
    int newCount = InterlockedDecrement(&mRefCount);
    if (newCount == 0)
        delete this;
    return newCount;
}

// IDeckLinkMemoryAllocator methods
HRESULT STDMETHODCALLTYPE   DeckLinkMemoryAllocator::AllocateBuffer (unsigned long bufferSize, void* *allocatedBuffer)
{
    if (mFrameCache.empty())
    {
        // Allocate memory on a page boundary
        *allocatedBuffer = VirtualAlloc(NULL, bufferSize, MEM_COMMIT | MEM_RESERVE | MEM_WRITE_WATCH | MEM_TOP_DOWN, PAGE_READWRITE);

        if (! *allocatedBuffer)
            return E_OUTOFMEMORY;

        mAllocatedSize[*allocatedBuffer] = bufferSize;
    }
    else
    {
        // Re-use most recently ReleaseBuffer'd address
        *allocatedBuffer = mFrameCache.back();
        mFrameCache.pop_back();
    }
    return S_OK;
}

HRESULT STDMETHODCALLTYPE   DeckLinkMemoryAllocator::ReleaseBuffer (void* buffer)
{
    if (mFrameCache.size() < mFrameCacheSize)
    {
        mFrameCache.push_back(buffer);
    }
    else
    {
        // No room left in cache, so free this buffer
        VirtualFree(buffer, 0, MEM_RELEASE);

        mAllocatedSize.erase(buffer);
    }
    return S_OK;
}

HRESULT STDMETHODCALLTYPE   DeckLinkMemoryAllocator::Commit ()
{
    return S_OK;
}

HRESULT STDMETHODCALLTYPE   DeckLinkMemoryAllocator::Decommit ()
{
    while (! mFrameCache.empty())
    {
        // Cleanup any frames allocated in AllocateBuffer() but not freed in ReleaseBuffer()
        VirtualFree(mFrameCache.back(), 0, MEM_RELEASE);
        mFrameCache.pop_back();
    }
    return S_OK;
}