subject_34616.htm

一些关于vc的问答

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序号：34616 发表者：qiujing 发表日期：2003-03-31 20:27:56
<br>主题：在线等：调节音量的错误
<br>内容：我用directshow写一个播放器。<BR>其中调节音量的那部分代码不起作用：<BR>HRESULT hr;<BR>&nbsp;&nbsp; CoInitialize(NULL);<BR>&nbsp;&nbsp; CoCreateInstance(CLSID_FilterGraph,NULL,CLSCTX_INPROC_SERVER, <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;IID_IGraphBuilder, (void **)&amp;pGraph);<BR>&nbsp;&nbsp; hr=pGraph-&gt;QueryInterface(IID_IBasicAudio, (void **)&amp;pAudio);<BR>&nbsp;&nbsp; if(FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return hr;<BR>&nbsp;&nbsp; hr=pGraph-&gt;QueryInterface(IID_IMediaControl, (void **)&amp;pMediaControl);<BR>&nbsp;&nbsp; if(FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return hr;<BR>&nbsp;&nbsp; hr=pGraph-&gt;QueryInterface(IID_IMediaEvent, (void **)&amp;pEvent);<BR>&nbsp;&nbsp; if(FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return hr;<BR>&nbsp;&nbsp; p_FilterState=State_Stopped;<BR>&nbsp;&nbsp; return true;<BR><BR><BR><BR>HRESULT CMedia::AudioUpMedia()<BR><BR>{ <BR>&nbsp;&nbsp;&nbsp;&nbsp;HRESULT hr;<BR>&nbsp;&nbsp;long plVolume=0;<BR>&nbsp;&nbsp;hr=pAudio-&gt;get_Volume(&amp;plVolume);<BR>&nbsp;&nbsp;if(FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return hr;<BR>&nbsp;&nbsp;<BR>&nbsp;&nbsp;plVolume=0;<BR>&nbsp;&nbsp;pAudio-&gt;put_Volume(plVolume);<BR>&nbsp;&nbsp;return S_OK;<BR><BR>}
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回复者：xiongli 回复日期：2003-04-01 00:27:29
<br>内容：我把dx8 demo 里面的一个jukebox player里面的代码拷贝过来替换了你的代码也没用。大家帮忙阿！<BR><BR>HRESULT MuteAudio(void)<BR>{<BR>&nbsp;&nbsp;&nbsp;&nbsp;HRESULT hr=S_OK;<BR>&nbsp;&nbsp;&nbsp;&nbsp;IBasicAudio *pBA=NULL;<BR>&nbsp;&nbsp;&nbsp;&nbsp;long lVolume;<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;if (!pGB)<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return S_OK;<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;hr =&nbsp;&nbsp;pGB-&gt;QueryInterface(IID_IBasicAudio, (void **)&amp;pBA);<BR>&nbsp;&nbsp;&nbsp;&nbsp;if (FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return S_OK;<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;// Read current volume<BR>&nbsp;&nbsp;&nbsp;&nbsp;hr = pBA-&gt;get_Volume(&amp;lVolume);<BR>&nbsp;&nbsp;&nbsp;&nbsp;if (hr == E_NOTIMPL)<BR>&nbsp;&nbsp;&nbsp;&nbsp;{<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Fail quietly if this is a video-only media file<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;pBA-&gt;Release();<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return hr;<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>&nbsp;&nbsp;&nbsp;&nbsp;else if (FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;{<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;RetailOutput(TEXT("Failed in pBA-&gt;get_Volume!&nbsp;&nbsp;hr=0x%x\r\n"), hr);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;pBA-&gt;Release();<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return hr;<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;lVolume = VOLUME_SILENCE;<BR>&nbsp;&nbsp;&nbsp;&nbsp;RetailOutput(TEXT("*** Media is MUTING.\r\n"));<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;// Set new volume<BR>&nbsp;&nbsp;&nbsp;&nbsp;hr = pBA-&gt;put_Volume(lVolume);<BR>&nbsp;&nbsp;&nbsp;&nbsp;if (FAILED(hr))<BR>&nbsp;&nbsp;&nbsp;&nbsp;{<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;RetailOutput(TEXT("Failed in pBA-&gt;put_Volume!&nbsp;&nbsp;hr=0x%x\r\n"), hr);<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;pBA-&gt;Release();<BR>&nbsp;&nbsp;&nbsp;&nbsp;return hr;<BR>}<BR>2003-4-1 0:28:08