14.7. MS ACM Dlls

14.7.1. Contents

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14.7.2. Status

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14.7.3. Caching

The MSACM/MSACM32 keeps some data cached for all known ACM drivers. Under the key

		  Software\Microsoft\AudioCompressionManager\DriverCache\<driver
		  name>
		
are kept for values:

  • aFormatTagCache which contains an array of DWORD. There are two DWORDs per cFormatTags entry. The first DWORD contains a format tag value, and the second the associated maximum size for a WAVEFORMATEX structure. (Fields dwFormatTag and cbFormatSize from ACMFORMATDETAILS)

  • cFilterTags contains the number of tags supported by the driver for filtering.

  • cFormatTags contains the number of tags support by the driver for conversions.

  • fdwSupport (the same as the one returned from acmDriverDetails).

The cFilterTags, cFormatTags, fdwSupport are the same values as the ones returned from acmDriverDetails function.