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The Audio Compression Manager

derrick030897
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Last Modified: 2012-05-04
Which DLL holds all the functions for the Audio Compression Manager? Has anyone used this with Visual Basic 4.0 to send a stream of audio to a particular device?
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Commented:
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MMSYSTEM.DLL       Waveform MIDI Auxiliary
MSVIDEO.DLL       Video capture, compression and decompression, rendering
MSACM.DRV       Audio compression and decompression mapper
MSACM.DLL       Compression and system management for the ACM

I don't believe there one single DLL. To quote from the MSDN:

"There are several ACM drivers which are automatically installed with the system. There are drivers which provide support for the compressed formats MS-ADPCM, IMA ADPCM, the GSM 6.10 standard, and the TrueSpeech voice coding format. There is also a PCM converter which converts between 8- and 16-bit PCM, between mono and stereo, and between different sampling frequencies. Other drivers can be installed at any time. The ACM provides API elements which allow an application to install a driver for its process only, preventing other processes from using it. "

And besides, I think you're chasing a technology that may be outdated soon. Another MSDN quote:

"The Audio Compression Manager (ACM) is included in Win32 to provide transparent run-time audio compression and decompression services. The current release of DirectSound does not support compressed wave formats; you must call ACM functions to decompress audio data before writing the data to a sound buffer.
While Microsoft will continue to support ACM, the ActiveMovie filter-based architecture is designed to provide services like compression and decompression to data streams. Look for these services in a future release of ActiveMovie."


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