| Microsoft DirectX 8.1 (C++) |
The DSCAPS structure describes the capabilities of a DirectSound device. Used by the IDirectSound8::GetCaps method.
Syntax
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 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 |
| 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 zero because the data need not be transferred anywhere. Similarly, the play processing overhead for hardware buffers is zero 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