Microsoft DirectX 9.0


The DSCAPS structure describes the capabilities of a device. It is 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; 
typedef const DSCAPS *LPCDSCAPS;



Size of the structure, in bytes. This member must be initialized before the structure is used.


Flags describing device capabilities. Can include the values shown in the following table.

Value Description
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 a primary buffer 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.


Number of primary buffers supported. This value will always be 1.


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.


Maximum number of static buffers.


Maximum number of streaming sound buffers.


Number of unallocated buffers. On WDM drivers, this includes dwFreeHw3DAllBuffers.


Number of unallocated static buffers.


Number of unallocated streaming buffers.


Maximum number of 3-D buffers.


Maximum number of static 3-D buffers.


Maximum number of streaming 3-D buffers.


Number of unallocated 3-D buffers.


Number of unallocated static 3-D buffers.


Number of unallocated streaming 3-D buffers.


Size, in bytes, of the amount of memory on the sound card that stores static sound buffers.


Size, in bytes, of the free memory on the sound card.


Size, in bytes, of the largest contiguous block of free memory on the sound card.


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.


The processing overhead, as a percentage of main processor cycles, needed to mix software buffers. This varies according to the bus type, the processor type, and the clock speed.


Not used.


Not used.


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.

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.


  Header: Declared in Dsound.h.

See Also