Audio Driver Registry Settings (Windows CE 5.0)
The following information describes the registry keys for ACM drivers and the software mixer.
ACM Drivers
[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\CODEC_GSM610]
"Prefix"="ACM"
"Dll"="gsm610.dll"
"Index"=dword:1
"Order"=dword:0
The Prefix registry value is used as part of the stream driver name when accessed through CreateFile.
The Dll registry value specifies the file name of the DLL containing the driver.
The Index registry value is appended to the stream driver name ACM1. If this is not set, the Device Manager chooses a number.
The following code example shows the Order registry value and the load order of the driver.
[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\FILTER]
"Prefix"="ACM"
"Dll"="msfilter.dll"
"Index"=dword:2
"Order"=dword:0
Software Mixer
[HKEY_LOCAL_MACHINE\Audio\SoftwareMixer]
"SampleRate"=dword:AC44
"Buffers"=dword:4
"BufferSize"=dword:800
"EnableLowPassFilter"=dword:1
"Priority 256"=dword:dc
The SampleRate registry value specifies the sample rate, measured in samples per second, that the software mixer will use when opening the audio device. The default is 0xAC44, which is equivalent to 44100 in decimal.
The Buffers registry value specifies the number of buffers used in the software mixer audio stream. The default is 4.
The BufferSize registry value specifies the size, measured in bytes, of the buffers used in the software mixer audio stream. The default is 0x800, which is equivalent to 2048 in decimal.
The EnableLowPassFilter registry value controls whether the software mixer applies a low pass filter when conducting sample rate conversion. This improves audio quality at the expense of the CPU overhead. The default is 1, which means the low pass filter is enabled.
The Priority 256 registry value specifies the thread priority at which the software mixer will run.
See Also
Audio Drivers | Audio Driver Samples
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