typedef struct _DSBCAPS {
DWORD dwSize;
DWORD dwFlags;
DWORD dwBufferBytes;
DWORD dwUnlockTransferRate;
DWORD dwPlayCpuOverhead;
} DSBCAPS, *LPDSBCAPS;
Specifies the capabilities of a DirectSound buffer object, for use by the IDirectSoundBuffer::GetCaps method.
Size of this structure, in bytes.
Flags that specify buffer-object capabilities.
The buffer must have frequency control capability.
The buffer must have pan control capability.
The buffer must have volume control capability.
Forces the buffer to use hardware mixing, even if DSBCAPS_STATIC is not specified. If the device does not support hardware mixing, or the required hardware memory is not available, the call to IDirectSound::CreateSoundBuffer will fail. The application must ensure that a mixing channel will be available for this buffer; this condition is not guaranteed.
Forces the buffer to be stored in software memory and use software mixing, even if DSBCAPS_STATIC is specified and hardware resources are available.
Indicates that the buffer is a primary sound buffer. If this value is not specified, a secondary buffer will be created.
Indicates that the buffer will be used for static sound data. Typically, these buffers are loaded once and played many times. These buffers are candidates for hardware memory.
Changes the focus behavior of the sound buffer. This flag can be specified in an IDirectSound::CreateSoundBuffer call. With this flag set, an application using DirectSound can continue to play its sticky focus buffers if the user switches to another application not using DirectSound. In this situation, the application's normal buffers will be muted, but the sticky focus buffers will still be audible. This is useful for non-game applications, such as movie playback (ActiveMovie™) when the user wants to hear the soundtrack while typing in Word or Excel, for example. If the user switches to DirectSound, all sound buffers, both normal and sticky focus, in the previous application will be muted.
Size of this buffer, in bytes.
Specifies the rate, in kilobytes per second, that data is transferred to the buffer memory when IDirectSoundBuffer::Unlock is called. High-performance applications can use this value to determine the time required for IDirectSoundBuffer::Unlock to execute. For software buffers located in system memory, the rate will be very high since no processing is required. For hardware buffers, the rate may be slower because the buffer might have to be downloaded to the sound card, which may have a limited transfer rate.
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.
The DSBCAPS structure contains information similar to that found in the DSBUFFERDESC structure passed to the IDirectSound::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).
Note that the dwFlags member of the DSBCAPS structure 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 will be specified, according to the location of the buffer memory. In the DSBUFFERDESC structure, these flags are optional and are used to force the buffer to be located in either hardware or software.