怎样用directshow控制语音播放速度

Question

用MediaPosition.put_Rate(Rate);好象只改变频率，播放速度没变，

Answer 1

bool UpdateStreamSample(IDirectDrawStreamSample* lpddss) {    HRESULT hr;    // Update the sample only if the application is active
    if (!g_bActive) {
        return true;
    }    // If we are seeking, update the stream clock
    if (g_stOffset) {
        g_stTime += g_stOffset;
        g_lpmmsStream->Seek(g_stTime);
    }#ifdef RENDER_TO_DEVICE_MEMORY
    // Make sure the flip has completed before changing texture contents or
    // we risk a render timeout
    do {
        hr = g_lpddsFront->GetFlipStatus(DDGFS_ISFLIPDONE);
    } while (hr == DDERR_WASSTILLDRAWING);    if (ResultFailed(hr, TEXT("IDirectDrawSurface::GetFlipStatus"))) {
        return false;
    }
#endif // RENDER_TO_DEVICE_MEMORY    // Update the texture with the contents of the video stream
    hr = lpddss->Update(0, NULL, NULL, 0);
    if (hr != MS_E_NOTRUNNING && FAILED(hr)) {
        ResultFailed(hr, TEXT("IDirectDrawStreamSample::Update"));
       return false;
    }    // If we've reached the end of the stream, reset it
    if (hr == MS_S_ENDOFSTREAM) {
      if (WaitForSingleObject(g_hEOS, 0) == WAIT_OBJECT_0)
      {
         hr = g_lpmmsStream->Seek(0);
         if (ResultFailed(hr, TEXT("IMultiMediaStream::Seek"))) {
            return false;
         }
      }        hr = lpddss->Update(0, NULL, NULL, 0);
        if (hr != MS_E_NOTRUNNING && FAILED(hr)) {
            ResultFailed(hr, TEXT("IDirectDrawStreamSample::Update"));
           return false;
        }
    }#ifndef RENDER_TO_DEVICE_MEMORY    if (g_lpddsStreamTarget && g_bStretchStream) {
        hr = g_lpddsSystemMemory->Blt(&g_rectTexture, g_lpddsStreamTarget, 
                                      &g_rectStream, DDBLT_WAIT, NULL);
        if (ResultFailed(hr, TEXT("IDirectDrawSurface::Blt"))) {
            return false;
        }
    }    // Load the source texture into the destination
    hr = g_lpd3dtDeviceMemory->Load(g_lpd3dtSystemMemory);
    if (FAILED(hr)) {
        if (hr != DDERR_SURFACELOST) {
            ResultFailed(hr, TEXT("IDirect3DTexture2::Load"));
            return false;
        }
    }#endif // !RENDER_TO_DEVICE_MEMORY    return true;}

Answer 2

Private m_objMediaPosition As IMediaPosition m_objMediaPosition.Rate=0.5~2应该有效果吧!