[問題] mp2 資訊如何填到 WAVEFORMATEX struct?

[nosrep (ㄎ)]

我用 ffmpeg 得到的 audio 資訊如下
Stream #0.1: Audio: mp2, 16000 Hz, mono, s16, 32 kb/s

我要如何轉到 WAVEFORMATEX 結構呢?
因為我要用 directshow 去解..但不知道怎麼填....
另外 CMediaType.SetSubtype() 也不知道該設什麼 ...


// code

                WAVEFORMATEX *pwfm = (WAVEFORMATEX
*)pmt->AllocFormatBuffer(sizeof(WAVEFORMATEX));
                if(NULL == pwfm)
                        return E_OUTOFMEMORY;

                // Initialize the VideoInfo structure before configuring its members
                ZeroMemory(pwfm, sizeof(WAVEFORMATEX));
                pwfm->cbSize = 0;
                pwfm->wFormatTag = WAVE_FORMAT_PCM; // ignore ?
                pwfm->nChannels = 1; //
                pwfm->nSamplesPerSec = 16000;
                pwfm->wBitsPerSample = 16; //8 bit
                pwfm->nBlockAlign = pwfm->nChannels * pwfm->wBitsPerSample / 8;
                pwfm->nAvgBytesPerSec = pwfm->nSamplesPerSec * pwfm->nBlockAlign;

                pmt->SetType(&MEDIATYPE_Audio);
                //pmt->SetSubtype(&MEDIASUBTYPE_PCM);
                pmt->SetSubtype(&MEDIASUBTYPE_MPEG1Audio);
                pmt->SetFormatType(&FORMAT_WaveFormatEx);
                pmt->SetTemporalCompression(TRUE);


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