ACM Wrapper Filter
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
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.
| Label | Value |
|---|---|
| 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:
|
| 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 |