我正在使用Intel硬件MFT将NV12帧编码为H264流,然后使用Live555通过RTP在局域网上传输已编码的帧,并在另一端设置ffplay以解码和显示相同的内容。使用软件编码器(SYNC或ASYNC软件MFT)时,设置可以正常工作,但是当使用Intel硬件MFT进行编码时,ffplay会抱怨SPS/PPS不可用,并且只显示混乱的屏幕。我已经发现,Intel硬件编码器在提供初始样本后触发MF_E_TRANSFORM_STREAM_CHANGE事件,并通过MF_MT_MPEG_SEQUENCE_HEADER提供SPS/PPS。我能够捕获MF_E_TRANSFORM_STREAM_CHANGE事件并获取序列头blob。
问题在于,Live555需要单独设置SPS和PPS。但是,我对从MF_MT_MPEG_SEQUENCE_HEADER blob中提取SPS和PPS感到非常困惑。
根据我的理解,并进一步查阅其他线程,SPS和PPS分别以00 00 00 01 67和00 00 00 01 68开头。但是,在我从Intel编码器接收到的blob中,我找不到这些序列。
https://github.com/cisco/openh264/issues/756 SPS起始标志: 00 00 00 01 67 PPS起始标志: 00 00 00 01 68
从英特尔MFT获取的序列头:
序列头大小为50
序列头: 0 0 1 27 64 0 28 ac 2b 40 3c 1 13 f2 e0 22 0 0 3 0 2 0 0 3 0 79 d0 80 f 42 0 3 d0 93 7b df 7 68 70 ca 80 0 0 0 1 28 ee 3c b0 0
vector<byte> sequenceHeaderData;
UINT32 sequenceHeaderDataSize = 0;
MFT_OUTPUT_DATA_BUFFER _outputDataBuffer;
memset(&_outputDataBuffer, 0, sizeof _outputDataBuffer);
_outputDataBuffer.dwStreamID = outputStreamID;
_outputDataBuffer.dwStatus = 0;
_outputDataBuffer.pEvents = nullptr;
_outputDataBuffer.pSample = nullptr;
HRESULT mftProcessOutput = _pEncoder->ProcessOutput(0, 1, &_outputDataBuffer, &processOutputStatus);
if (MF_E_TRANSFORM_STREAM_CHANGE == mftProcessOutput)
{
// some encoders want to renegotiate the output format.
if (_outputDataBuffer.dwStatus & MFT_OUTPUT_DATA_BUFFER_FORMAT_CHANGE)
{
CComPtr<IMFMediaType> pNewOutputMediaType = nullptr;
HRESULT res = _pEncoder->GetOutputAvailableType(outputStreamID, 1, &pNewOutputMediaType);
res = _pEncoder->SetOutputType(outputStreamID, pNewOutputMediaType, 0);//setting the type again
CHECK_HR(res, "Failed to set output type during stream change");
{
CComPtr<IMFMediaType> pCurOutputMediaType = nullptr;
HRESULT res = _pEncoder->GetOutputAvailableType(outputStreamID, 1, &pCurOutputMediaType);
res = pCurOutputMediaType->GetBlobSize(MF_MT_MPEG_SEQUENCE_HEADER, &sequenceHeaderDataSize);
if (SUCCEEDED(res) && sequenceHeaderDataSize > 0)
{
sequenceHeaderData.resize(sequenceHeaderDataSize);
pCurOutputMediaType->GetBlob(MF_MT_MPEG_SEQUENCE_HEADER, sequenceHeaderData.data(), sequenceHeaderDataSize, NULL);
cout << "Sequence header size " << sequenceHeaderDataSize << std::endl;
}
else
{
cout << "Sequence header is not available" << std::endl;
}
}
}
}