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我正在尝试使用 Media Foundation Transforms 将 HE-AAC 音频流（由 RTP 库 live555 接收）转换为 PCM（通过waveOutXxxWin32 API 播放）。但是，目前我正在处理预先录制的数据包。

当我打电话时IMFTransform::ProcessOutput，它会返回MF_E_TRANSFORM_STREAM_CHANGE。这方面的文档_MFT_PROCESS_OUTPUT_STATUS表明我应该确定正确的流类型，然后IMFTransform::SetOutputType再次调用。

但是，我无法确定SetOutputType.

作为参考，流的 RTSP 描述是

m=audio 0 RTP/AVP 97
a=rtpmap:97 mpeg4-generic/16000/1
a=fmtp:97 streamtype=5; profile-level-id=15; mode=AAC-hbr; config=1408; 
  sizeLength=13; indexLength=3; indexDeltaLength=3; profile=1; bitrate=32000;

我的代码是（对不起长度；为简洁起见删除了错误处理）

static IMFMediaType *s_inputMediaType;
static IMFMediaType *s_outputMediaType;
static IMFTransform *s_transform;
static DWORD         s_outputSampleSize;

static void InitMFT()
{
    HRESULT res;
    res = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED); // probably should use threaded in production
#if 0
    res = MFCreateMediaType(&inputMediaType);
    res = MFCreateMediaType(&outputMediaType);

    res = inputMediaType->SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Audio);
    res = inputMediaType->SetGUID(MF_MT_SUBTYPE, MFAudioFormat_AAC);
    res = inputMediaType->SetUINT32(MF_MT_AAC_AUDIO_PROFILE_LEVEL_INDICATION, 15);
    res = inputMediaType->SetUINT32(MF_MT_AAC_PAYLOAD_TYPE, 1); // Audio Data Transport Stream

    res = outputMediaType->SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Audio);
    res = outputMediaType->SetGUID(MF_MT_SUBTYPE, MFAudioFormat_PCM);
    res = outputMediaType->SetUINT32(MF_MT_SAMPLE_SIZE, 2);
    res = outputMediaType->SetUINT32(MF_MT_AUDIO_NUM_CHANNELS, 2);
    res = outputMediaType->SetUINT32(MF_MT_AUDIO_BITS_PER_SAMPLE, 8 * 2);
    res = outputMediaType->SetUINT32(MF_MT_AUDIO_SAMPLES_PER_SECOND, 8000);
    res = outputMediaType->SetUINT32(MF_MT_AUDIO_AVG_BYTES_PER_SECOND, 8000 * 2 *2);
#endif
    CLSID *clsids = NULL;
    UINT32 clsidCount=0;

    MFT_REGISTER_TYPE_INFO inputType  = {MFMediaType_Audio, MEDIASUBTYPE_MPEG_HEAAC}; // WAVE_FORMAT_MPEG_HEAAC can't be searched for
    MFT_REGISTER_TYPE_INFO outputType = {MFMediaType_Audio, WAVE_FORMAT_PCM};         // MEDIASUBTYPE_PCM doesn't exist (but can be search for if created)

    res = MFTEnum(MFT_CATEGORY_AUDIO_DECODER, 0,
                  &inputType,
                  NULL, /* &outputType, */ // search fails if outputType is not NULL
                  NULL, &clsids, &clsidCount);

    ListTranscoders(clsids, clsidCount);

    res = CoCreateInstance(clsids[0], NULL, CLSCTX_ALL, IID_PPV_ARGS(&s_transform));

    /* GetStreamCount and GetStreamIDs always return E_NOTIMPL */
    DWORD inputCount;
    DWORD outputCount;
    res = s_transform->GetStreamCount(&inputCount, &outputCount);

    DWORD inputIDs[16];
    DWORD outputIDs[16];

    res = s_transform->GetStreamIDs(inputCount, inputIDs,
                                  outputCount, outputIDs);

    res = s_transform->GetInputAvailableType(0, 0, &s_inputMediaType);
    res = s_transform->SetInputType(0, s_inputMediaType, 0);

    res = s_transform->GetOutputAvailableType(0, 1, &s_outputMediaType); // 1 here is because PCM outputer is the second output offered in ListTranscoders
    res = s_transform->SetOutputType(0, s_outputMediaType, 0);

    MFT_OUTPUT_STREAM_INFO outputStreamInfo;
    res = s_transform->GetOutputStreamInfo(0, &outputStreamInfo); 
    s_outputSampleSize = outputStreamInfo.cbSize;

    GUID inputCodec;
    GUID outputCodec;

    res = s_inputMediaType ->GetGUID(MF_MT_SUBTYPE, &inputCodec);
    res = s_outputMediaType->GetGUID(MF_MT_SUBTYPE, &outputCodec);

    CoTaskMemFree(clsids);
}

/*
http://msdn.microsoft.com/en-us/library/bb530106%28v=vs.85%29.aspx
http://msdn.microsoft.com/en-us/library/bb530123%28v=vs.85%29.aspx
*/

void ProcessData(const void* inputData,  DWORD inputSize,
                       void* outputData, DWORD &outputSize)
{
    HRESULT         res;
    IMFSample      *pSample;
    IMFMediaBuffer *pBuffer;
    BYTE *pData = NULL;

    /**** Create an input sample buffer, from the supplied data ****/
    res = MFCreateSample(&pSample);
    res = MFCreateMemoryBuffer(inputSize, &pBuffer);
    res = pBuffer->Lock(&pData, NULL, NULL);
    memcpy_s(pData, inputSize, inputData, inputSize);
    res = pBuffer->SetCurrentLength(inputSize);
    res = pBuffer->Unlock();
    res = pSample->AddBuffer(pBuffer);

    /**** Create output buffer ****/
    IMFSample      *pOutputSample;
    IMFMediaBuffer *pOutputBuffer;

    res = MFCreateSample(&pOutputSample);
    res = MFCreateMemoryBuffer(s_outputSampleSize, &pOutputBuffer);
    res = pOutputSample->AddBuffer(pOutputBuffer);

    MFT_OUTPUT_DATA_BUFFER outputDataBuffer; // can be an array
    outputDataBuffer.dwStreamID=0;
    outputDataBuffer.pSample=pOutputSample;
    outputDataBuffer.dwStatus=0;
    outputDataBuffer.pEvents = NULL;

    DWORD outputStatus=0;

    /*** Process the data, and get it back ****/
    res = s_transform->ProcessInput(0, pSample, 0);
    res = s_transform->ProcessOutput( MFT_PROCESS_OUTPUT_DISCARD_WHEN_NO_BUFFER, 
                                   1, &outputDataBuffer, &outputStatus);


    if (res==MF_E_TRANSFORM_STREAM_CHANGE)
    {
        // http://msdn.microsoft.com/en-us/library/windows/desktop/dd797815%28v=vs.85%29.aspx
        // indicates that the output always changes
        // but not how to handle it

        /* GetStreamCount and GetStreamIDs always return E_NOTIMPL */

        DWORD inputCount;
        DWORD outputCount;
        res = s_transform->GetStreamCount(&inputCount, &outputCount);

        DWORD inputIDs[16];
        DWORD outputIDs[16];

        res = s_transform->GetStreamIDs(inputCount, inputIDs,
                                      outputCount, outputIDs);

        res = s_transform->GetInputAvailableType(0, 0, &s_inputMediaType);
        res = s_transform->SetInputType(0, s_inputMediaType, 0);

        res = s_transform->GetOutputAvailableType(0, 1, &s_outputMediaType); // 1 here is because PCM outputer is the second output offered
        res = s_transform->SetOutputType(0, s_outputMediaType, 0);
    }

    /**** Extract converted audio from the sample ****/
    DWORD dwNumOutputBuffers, i;
    res = outputDataBuffer.pSample->GetBufferCount(&dwNumOutputBuffers);

    for(i=0; i<dwNumOutputBuffers; i++)
    {
        IMFMediaBuffer *outputBuffer;
        res = outputDataBuffer.pSample->GetBufferByIndex(i, &outputBuffer);
        BYTE *outData;
        DWORD outDataLen = 0;

        res = outputBuffer->Lock(&outData, NULL, &outDataLen);

        memcpy(outputBuffer, outData, outDataLen);

        res = outputBuffer->Unlock();
    }

    /* TODO: Release any neccessery references */
}
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1 回答 1

1

我正在做一个非常相似的事情。你必须做一个设置输出类型，否则你的下一个过程输入会给你MF_E_TRANSFORM_TYPE_NOT_SET，

您还必须刷新解码器，否则您的下一个进程输入将返回 MF_E_NOTACCEPTING。使用您的代码，我通过删除在此行之后添加的设置输入类型 res 来使其工作

res = s_transform->GetOutputAvailableType(0, 1, &s_outputMediaType); // 1 here is because PCM outputer is the second output offered
    GUID outputCodec;
    res = s_outputMediaType->GetGUID(MF_MT_SUBTYPE, &outputCodec);
    if (outputCodec == MFAudioFormat_PCM){
        printf("\nDecoder Output is expecting pcm format");                 
        res = s_transform->SetOutputType(0, s_outputMediaType, 0);//setting the type again

    }
    if (outputCodec == MFAudioFormat_Float){
        printf("\nDecoder Output is expecting float pcm format");
    }
    s_transform->ProcessMessage(MFT_MESSAGE_COMMAND_FLUSH,NULL);        

    return res;//no output coming get another input to process.

为了测试，我使用来自源阅读器的样本到一个好的文件。一定要播放很多数据包，因为一些包含“安静”的数据包可能很短并且全为 0。

此外，因此 url http://msdn.microsoft.com/en-us/library/windows/desktop/ff485864%28v=vs.85%29.aspx很好地指定了如何配置输出。这是非常有用的。

仔细阅读http://msdn.microsoft.com/en-us/library/windows/desktop/dd742784%28v=vs.85%29.aspx 您会注意到输入媒体类型上的某些属性（MF_MT_AUDIO_BITS_PER_SAMPLE）告诉解码器如何格式化输出。如果您能够更全面地指定所需的输入和输出，则可以避免流更改。您的第一个样本可能是 MF_E_TRANSFORM_NEED_MORE_INPUT 。

于 2014-10-31T14:27:26.927 回答