Parameter meaning of CBasePin::GetMediaType(int iPosition, ...) method
- by user325320
Thanks to everyone who views my question.
http://msdn.microsoft.com/en-us/library/windows/desktop/dd368709(v=vs.85).aspx
It is not very clear from the documentation regarding the iPosition parameter for
virtual HRESULT GetMediaType(
int iPosition,
CMediaType *pMediaType
);
It is said "Zero-based index value.", but what kind of index it is? the index of the samples?
I have a source filter sending the H.264 NALU flows (MEDIASUBTYPE_AVC1) and it works very well except that the SPS/PPS may be changed after the video is played for a while.
The SPS and PPS are appended to the MPEG2VIDEOINFO structure, which is passed in CMediaType::SetFormat method when GetMediaType method is called.
and there is another version of GetMediaType which accepts the iPosition parameter. It seems I can use this method to update the SPS / PPS.
My question is: What does the iPosition param mean, and how does Decoder Filter know which SPS/PPS are assigned for each NALU sample.
HRESULT GetMediaType(int iPosition, CMediaType *pMediaType)
{
ATLTRACE( "\nGetMediaType( iPosition = %d ) ", iPosition);
CheckPointer(pMediaType,E_POINTER);
CAutoLock lock(m_pFilter->pStateLock());
if (iPosition < 0)
{
return E_INVALIDARG;
}
if (iPosition == 0)
{
pMediaType->InitMediaType();
pMediaType->SetType(&MEDIATYPE_Video);
pMediaType->SetFormatType(&FORMAT_MPEG2Video);
pMediaType->SetSubtype(&MEDIASUBTYPE_AVC1);
pMediaType->SetVariableSize();
}
int nCurrentSampleID;
DWORD dwSize = m_pFlvFile->GetVideoFormatBufferSize(nCurrentSampleID);
LPBYTE pBuffer = pMediaType->ReallocFormatBuffer(dwSize);
memcpy( pBuffer, m_pFlvFile->GetVideoFormatBuffer(nCurrentSampleID), dwSize);
pMediaType->SetFormat(pBuffer, dwSize);
return S_OK;
}
