Microsoft DirectX 8.0 (C++)

DSCAPS

Describes the capabilities of a DirectSound device. Used by the IDirectSound8::GetCaps method.

typedef { 
    DWORD  dwSize; 
    DWORD  dwFlags;  
    DWORD  dwMinSecondarySampleRate; 
    DWORD  dwMaxSecondarySampleRate; 
    DWORD  dwPrimaryBuffers; 
    DWORD  dwMaxHwMixingAllBuffers; 
    DWORD  dwMaxHwMixingStaticBuffers; 
    DWORD  dwMaxHwMixingStreamingBuffers; 
    DWORD  dwFreeHwMixingAllBuffers; 
    DWORD  dwFreeHwMixingStaticBuffers; 
    DWORD  dwFreeHwMixingStreamingBuffers; 
    DWORD  dwMaxHw3DAllBuffers; 
    DWORD  dwMaxHw3DStaticBuffers; 
    DWORD  dwMaxHw3DStreamingBuffers; 
    DWORD  dwFreeHw3DAllBuffers; 
    DWORD  dwFreeHw3DStaticBuffers; 
    DWORD  dwFreeHw3DStreamingBuffers; 
    DWORD  dwTotalHwMemBytes; 
    DWORD  dwFreeHwMemBytes; 
    DWORD  dwMaxContigFreeHwMemBytes; 
    DWORD  dwUnlockTransferRateHwBuffers; 
    DWORD  dwPlayCpuOverheadSwBuffers; 
    DWORD  dwReserved1; 
    DWORD  dwReserved2; 
} DSCAPS, *LPDSCAPS; 
 
typedef const DSCAPS *LPCDSCAPS;

Members

dwSize
Size of the structure, in bytes. This member must be initialized before the structure is used.
dwFlags
Flags describing device capabilities. Can include the following values.
DSCAPS_CERTIFIED
The driver has been tested and certified by Microsoft. This flag is always set for WDM drivers. To test for certification, use IDirectSound8::VerifyCertification.
DSCAPS_CONTINUOUSRATE
The device supports all sample rates between the dwMinSecondarySampleRate and dwMaxSecondarySampleRate member values. Typically, this means that the actual output rate will be within +/- 10 hertz (Hz) of the requested frequency.
DSCAPS_EMULDRIVER
The device does not have a DirectSound driver installed, so it is being emulated through the waveform-audio functions. Performance degradation should be expected.
DSCAPS_PRIMARY16BIT
The device supports primary sound buffers with 16-bit samples.
DSCAPS_PRIMARY8BIT
The device supports primary buffers with 8-bit samples.
DSCAPS_PRIMARYMONO
The device supports monophonic primary buffers.
DSCAPS_PRIMARYSTEREO
The device supports stereo primary buffers.
DSCAPS_SECONDARY16BIT
The device supports hardware-mixed secondary sound buffers with 16-bit samples.
DSCAPS_SECONDARY8BIT
The device supports hardware-mixed secondary buffers with 8-bit samples.
DSCAPS_SECONDARYMONO
The device supports hardware-mixed monophonic secondary buffers.
DSCAPS_SECONDARYSTEREO
The device supports hardware-mixed stereo secondary buffers.
dwMinSecondarySampleRate, dwMaxSecondarySampleRate
Minimum and maximum sample rate specifications that are supported by this device's hardware secondary sound buffers.
dwPrimaryBuffers
Number of primary buffers supported. This value will always be 1.
dwMaxHwMixingAllBuffers
Number of buffers that can be mixed in hardware. This member can be less than the sum of dwMaxHwMixingStaticBuffers and dwMaxHwMixingStreamingBuffers. Resource tradeoffs frequently occur.
dwMaxHwMixingStaticBuffers
Maximum number of static buffers.
dwMaxHwMixingStreamingBuffers
Maximum number of streaming sound buffers.
dwFreeHwMixingAllBuffers
Number of unallocated buffers. On WDM drivers, this includes dwFreeHw3DAllBuffers.
dwFreeHwMixingStaticBuffers
Number of unallocated static buffers.
dwFreeHwMixingStreamingBuffers
Number of unallocated streaming buffers.
dwMaxHw3DAllBuffers
Maximum number of 3-D buffers.
dwMaxHw3DStaticBuffers
Maximum number of static 3-D buffers.
dwMaxHw3DStreamingBuffers
Maximum number of streaming 3-D buffers.
dwFreeHw3DAllBuffers
Number of unallocated 3-D buffers.
dwFreeHw3DStaticBuffers
Number of unallocated static 3-D buffers.
dwFreeHw3DStreamingBuffers
Number of unallocated streaming 3-D buffers.
dwTotalHwMemBytes
Size, in bytes, of the amount of memory on the sound card that stores static sound buffers.
dwFreeHwMemBytes
Size, in bytes, of the free memory on the sound card.
dwMaxContigFreeHwMemBytes
Size, in bytes, of the largest contiguous block of free memory on the sound card.
dwUnlockTransferRateHwBuffers
Description of the rate, in kilobytes per second, at which data can be transferred to hardware static sound buffers. This and the number of bytes transferred determines the duration of a call to the IDirectSoundBuffer8::Unlock method.
dwPlayCpuOverheadSwBuffers
Description of the processing overhead, as a percentage of the central processing unit, needed to mix software buffers (those located in main system memory). This varies according to the bus type, the processor type, and the clock speed.

The unlock transfer rate for software buffers is 0 because the data need not be transferred anywhere. Similarly, the play processing overhead for hardware buffers is 0 because the mixing is done by the sound device.

dwReserved1
Not used.
dwReserved2
Not used.

Remarks

Some audio cards may be unable to report accurately the number of available or free hardware buffers. This can happen, for example, when the card can play more sounds at lower sampling rates than at higher rates. In general, a nonzero value in any of the members relating to number of free hardware buffers signifies that at least one hardware resource of the appropriate type is available.

Requirements

  Header: Declared in dsound.h.

See Also

IDirectSound8::GetCaps