Audio Capture Filter (Compact 7)
3/12/2014
The Audio Capture filter represents an audio capture device. It has one capture output pin and one input pin for each media type on the card such as Line In, Mic and CD.
| Filter property | Description |
|---|---|
Filter Interfaces |
IAMAudioInputMixer, IAMFilterMiscFlags, IAMResourceControl, IPersistPropertyBag, ISpecifyPropertyPages |
Input Pin Media Types |
MEDIATYPE_AnalogAudio, MEDIASUBTYPE_NULL |
Input Pin Interfaces |
IMemInputPin, IPin, IQualityControl, IAMAudioInputMixer |
Output Pin Media Types |
MEDIATYPE_Audio, MEDIASUBTYPE_NULL |
Output Pin Interfaces |
IAMBufferNegotiation Interface, IAMPushSource, IAMStreamConfig Interface, IAMStreamControl, IKsPropertySet Interface, IReferenceClock Interface, IQualityControl |
Filter CLSID |
Not applicable |
Executable |
quartz.dll |
MERIT_DO_NOT_USE |
|
Filter Category |
CLSID_AudioInputDeviceCategory |
Remarks
The input pins correspond to physical hardware connections. They are never connected to DirectShow filters.
GSM610 uses the PCM subtype but requires a specific wave format tag to select it.
Code Example
The code example below shows how to set the format on the audio capture filter to enable GSM610 output:
AM_MEDIA_TYPE mt;
GSM610WAVEFORMAT wf;
#ifndef WAVE_FORMAT_GSM610
#define WAVE_FORMAT_GSM610 0x31
#endif
mt.majortype = MEDIATYPE_Audio;
mt.bFixedSizeSamples = true;
mt.bTemporalCompression=false;
mt.lSampleSize=4096;
mt.formattype=FORMAT_WaveFormatEx;
mt.pUnk=NULL;
wf.wfx.wFormatTag = WAVE_FORMAT_GSM610;
wf.wfx.nChannels = 0x0001;
wf.wfx.nSamplesPerSec = 0x1f40;
wf.wfx.nAvgBytesPerSec = 0x00000659;
wf.wfx.nBlockAlign = 0x0041;
wf.wfx.wBitsPerSample = 0x0000;
wf.wfx.cbSize = 0x0002;
wf.wSamplesPerBlock = 0x140;
mt.cbFormat = sizeof( GSM610WAVEFORMAT );
mt.pbFormat = (BYTE *) &wf;