The ACM Wrapper filter enables Audio Compression Manager (ACM) codecs to join a filter graph. It can act either as a decompression filter or as a compression filter.
As a decompression filter, the ACM Wrapper appears in the "DirectShow Filters" category (CLSID_LegacyAmFilterCategory) and has a merit of MERIT_NORMAL. The connection media type on the input pin determines which codec the filter uses. Typically, the application does not need to add the filter to the filter graph; it is pulled in automatically by the Filter Graph Manager when needed. Decompression is only to PCM audio.
As a compression filter, the ACM Wrapper appears in the "Audio Compressors" category (CLSID_AudioCompressorCategory) and has a merit of MERIT_DO_NOT_USE. Each codec appears as a separate instance. For compression, you cannot directly create the filter with CoCreateInstance. Instead, you must use the system device enumerator. For more information, see Using the System Device Enumerator.
| Filter interfaces | IBaseFilter, IPersist, IPersistPropertyBag |
| Input pin media types | MEDIATYPE_Audio, MEDIASUBTYPE_NULL, FORMAT_WaveFormatEx |
| Input pin interfaces | IMemInputPin, IPin, IQualityControl |
| Output pin media types | MEDIATYPE_Audio, MEDIASUBTYPE_PCM, FORMAT_WaveFormatEx. Any combination of the following are possible:
- Samples per second (kHz): 44.1, 22.05, 11.025, or 8.0.
- Channels: Stereo or mono.
- Bits per sample: 8 or 16.
|
| Output pin interfaces | IAMStreamConfig, IMediaPosition, IMediaSeeking, IPin, IQualityControl |
| Filter CLSID | CLSID_ACMWrapper |
| Property Page CLSID | No property page. |
| Executable | Quartz.dll |
| Merit | MERIT_NORMAL or MERIT_DO_NOT_USE |
| Filter Category | CLSID_LegacyAmFilterCategory or CLSID_AudioCompressorCategory |
See Also
- DirectShow Filters
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Build date: 10/19/2009