Microsoft DirectX 8.0 (C++)

DSBCAPS

Describes the capabilities of a DirectSound buffer object. Used by the IDirectSoundBuffer8::GetCaps method.

typedef struct { 
    DWORD  dwSize; 
    DWORD  dwFlags; 
    DWORD  dwBufferBytes; 
    DWORD  dwUnlockTransferRate; 
    DWORD  dwPlayCpuOverhead; 
} DSBCAPS, *LPDSBCAPS; 
 
typedef const DSBCAPS *LPCDSBCAPS;

Members

dwSize
Size of the structure, in bytes. This member must be initialized before the structure is used.
dwFlags
Flags that specify buffer-object capabilities.
DSBCAPS_CTRL3D
The buffer has 3-D control capability.
DSBCAPS_CTRLFREQUENCY
The buffer has frequency control capability.
DSBCAPS_CTRLFX
The buffer supports effects processing.
DSBCAPS_CTRLPAN
The buffer has pan control capability.
DSBCAPS_CTRLVOLUME
The buffer has volume control capability.
DSBCAPS_CTRLPOSITIONNOTIFY
The buffer has position notification capability. See the Remarks for DSBUFFERDESC.
DSBCAPS_GETCURRENTPOSITION2
Indicates that IDirectSoundBuffer8::GetCurrentPosition should use the new behavior of the play cursor. In DirectSound in DirectX 1, the play cursor was significantly ahead of the actual playing sound on emulated sound cards; it was directly behind the write cursor. Now, if the DSBCAPS_GETCURRENTPOSITION2 flag is specified, the application can get a more accurate play cursor. If this flag is not specified, the old behavior is preserved for compatibility. Note that this flag affects only emulated sound cards; if a DirectSound driver is present, the play cursor is accurate for DirectSound in all versions of DirectX.
DSBCAPS_GLOBALFOCUS
The buffer is a global sound buffer. With this flag set, an application using DirectSound can continue to play its buffers if the user switches focus to another application, even if the new application uses DirectSound. The one exception is if you switch focus to a DirectSound application that uses the DSSCL_WRITEPRIMARY flag for its cooperative level. In this case, the global sounds from other applications will not be audible.
DSBCAPS_LOCDEFER
The buffer can be assigned to a hardware or software resource at play time, or when IDirectSoundBuffer8::AcquireResources is called.
DSBCAPS_LOCHARDWARE
The buffer uses hardware mixing.
DSBCAPS_LOCSOFTWARE
The buffer is in software memory and uses software mixing.
DSBCAPS_MUTE3DATMAXDISTANCE
The sound is reduced to silence at the maximum distance. The buffer will stop playing when the maximum distance is exceeded, so that processor time is not wasted.
DSBCAPS_PRIMARYBUFFER
The buffer is a primary sound buffer.
DSBCAPS_STATIC
The buffer is in on-board hardware memory.
DSBCAPS_STICKYFOCUS
The buffer has sticky focus. If the user switches to another application not using DirectSound, the buffer is still audible. However, if the user switches to another DirectSound application, the buffer is muted.
dwBufferBytes
Size of this buffer, in bytes.
dwUnlockTransferRate
Specifies the rate, in kilobytes per second, at which data is transferred to the buffer memory when IDirectSoundBuffer8::Unlock is called. High-performance applications can use this value to determine the time required for IDirectSoundBuffer8::Unlock to execute. For software buffers located in system memory, the rate will be very high because no processing is required. For hardware buffers, the rate might be slower because the buffer might have to be downloaded to the sound card, which might have a limited transfer rate.
dwPlayCpuOverhead
Specifies the processing overhead as a percentage of main processing cycles needed to mix this sound buffer. For hardware buffers, this member will be 0 because the mixing is performed by the sound device. For software buffers, this member depends on the buffer format and the speed of the system processor.

Remarks

The DSBCAPS structure contains information similar to that found in the DSBUFFERDESC structure passed to the IDirectSound8::CreateSoundBuffer method, with some additional information. Additional information includes the location of the buffer (hardware or software) and some cost measures (such as the time to download the buffer if located in hardware, and the processing overhead to play the buffer if it is mixed in software).

The dwFlags member contains the same flags used by the DSBUFFERDESC structure. The only difference is that in the DSBCAPS structure, either the DSBCAPS_LOCHARDWARE or DSBCAPS_LOCSOFTWARE flag is specified, according to the location of the buffer. In the DSBUFFERDESC structure, these flags are optional and are used to force the buffer to be located in either hardware or software.

Requirements

  Header: Declared in dsound.h.

See Also

IDirectSound8::CreateSoundBuffer, IDirectSoundBuffer8::GetCaps