The Audio Compression Manager

derrick030897
derrick030897 used Ask the Experts™
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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:
There may be no single answer ...

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And besides, I think you're chasing a technology that may be outdated soon.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