我有一个使用 DSPACK 组件库用 Delphi 6 编写的 DirectShow 应用程序。我在启用过滤器上的输入行时遇到了一个奇怪的问题。我搜索引脚，直到找到输入线，在本例中名为“麦克风”，并在过滤器图处于活动状态时对其调用 put_Enable(true)。当我这样做时，我得到一个 $80004005 的“未指定错误”作为 HRESULT。
在启用输入线之前，我正在为过滤器设置输出音频媒体类型，但有些东西无法正常工作。我用来创建应用程序的原始 DirectShow 示例运行良好。我相信我正在按照完全相同的步骤构建我的过滤器图，当然我可能错过了一些东西。有人对我可以尝试解决此问题的事情有任何提示或想法吗？下面的代码片段部分显示了我正在做的事情，但不是所有导致它的步骤，因为它们非常冗长。我用于测试的捕获设备是一个 VOIP 耳机，带有一条名为“麦克风”的输入线。
// The function I call to find an enable the first input line I find in the filter.
function findAndEnableFirstInputLineFound(intfBaseFilter: IBaseFilter; out strInputLineUsed: string): boolean;
var
thePinList: TPinList;
i: integer;
ABool: LongBool;
begin
strInputLineUsed := '';
if not Assigned(intfBaseFilter) then
raise Exception.Create('(findAndEnableFirstInputLineFound) The base filter interface object is unassigned.');
// Now enable the first input source we can find.
Result := false;
thePinList := TPinList.Create(intfBaseFilter);
try
if thePinList.Count > 0 then
begin
// Scan the pin list looking for an input pin.
i := 0;
while (i < thePinList.Count) and (not Result) do
begin
if thePinList.PinInfo[i].dir = PINDIR_INPUT then
begin
// Found one. Enable it.
with thePinList.Items[i] as IAMAudioInputMixer do
begin
CheckDSEror(put_Enable(true)); // $80004005 error occurs here.
// Return the name of the input line used.
strInputLineUsed := thePinList.PinInfo[i].achName;
end; // with thePinList.Items[i] as IAMAudioInputMixer do
Result := true;
break; // Stop looping.
end; // if thePinList.PinInfo[i].dir = PINDIR_INPUT then
Inc(i);
end; // while()
end; // if thePinList.Count > 0 then
finally
thePinList.Free;
end; // try
end;
// The initialization procedure that calls the function above. It is run after the
// the Filter Graph is activated but before it is played.
procedure TDXChain_wavaudio.initializeCaptureFilter;
var
theMediaType: TMediaType;
intfCapturePin: IPin;
aryEnabledInputLines: TDynamicStringArray;
begin
theMediaType := nil;
intfCapturePin := nil;
aryEnabledInputLines := nil;
if not FFilterGraph.Active then
raise Exception.Create('(TDXChain_wavaudio.Create::initializeCaptureFilter) The Filter Graph is INACTIVE.');
if Assigned(FCaptureFilter) then
begin
// Make sure the Capture Filter's output pins supports the
// configured WAV format.
with FOwner.ati_WaveFormatEx do
begin
// if not Assigned(findAudioMediaTypeByFormat(FCaptureFilter_mediatypes, nSamplesPerSec, wBitsPerSample, nChannels)) then
theMediaType := findAudioMediaTypeExt_outputs(FCaptureFilter as IBaseFilter, nSamplesPerSec, wBitsPerSample, nChannels);
if not Assigned(theMediaType) then
// The capture device does not directly support the desired
// WAV format. This is not allowed currently.
raise Exception.Create('(TDXChain_wavaudio.Create::initializeCaptureFilter) The audio input device''s output pins does not support the given WAV format: '
+ CRLF
+ Format('(Device name: %s, Sample Rate: %d, Bits Per Sample: %d, Number of Channels: %d)',
[FOwner.FCaptureFilterConfigInfo.filterName, nSamplesPerSec, wBitsPerSample, nChannels])
);
// -------------- SET OUTPUT PINS TO MEDIA TYPE -------------
// Set the output pins to the desired format.
setPinAudMediaType_outputs(FCaptureFilter, theMediaType.AMMediaType);
// Don't need the media type anymore.
FreeAndNil(theMediaType);
end; // with FOwner.ati_WaveFormatEx do
// Enable at least one input line.
if FOwner.FCaptureFilterConfigInfo.inputPinName = '' then
begin
// No input name was specified so use the first one found.
if not findAndEnableFirstInputLineFound(FCaptureFilter as IBaseFilter, FOwner.FInputLineUsed) then
raise Exception.Create(
'(TDXChain_wavaudio.Create::initializeCaptureFilter) Unable to find a suitable input line for the audio input device named: '
+ FOwner.FCaptureFilterConfigInfo.filterName);
end
else
begin
// Now find the desired available input line and enable it.
if not findAndEnableInputLineByName(FOwner.FCaptureFilterConfigInfo.inputPinName, FCaptureFilter as IBaseFilter, FOwner.FInputLineUsed) then
raise Exception.Create(
'(TDXChain_wavaudio.Create::initializeCaptureFilter) Unable to find the input line named ('
+ FOwner.FCaptureFilterConfigInfo.inputPinName
+ ') for the audio input device named: '
+ FOwner.FCaptureFilterConfigInfo.filterName);
end; // else - if FOwner.FCaptureFilterConfigInfo.inputPinName = '' then
aryEnabledInputLines := getEnabledInputLineNames(FCaptureFilter as IBaseFilter);
if Length(aryEnabledInputLines) < 1 then
raise Exception.Create('(TDXChain_wavaudio.Create::initializeCaptureFilter) No input lines are enabled..');
// ------------------ BUFFER LATENCY --------------------
// Get a reference to the output pin for audio the capture device.
with FCaptureFilter as IBaseFilter do
CheckDSError(findPin(StringToOleStr('Capture'), intfCapturePin));
if not Assigned(intfCapturePin) then
raise Exception.Create('(TDXChain_wavaudio.Create::initializeCaptureFilter) Unable to find the audio input device''s Capture output pin.');
// Set the capture device buffer to 50 ms worth of audio data to
// reduce latency. NOTE: This will fail if the device does not
// support the latency you desire so make sure you watch out for that.
setBufferLatency(intfCapturePin as IAMBufferNegotiation, FOwner.ati_BufferLatency_ms, FOwner.FMediaType);
end; // if Assigned(FCaptureFilter) then
end;