Buffer Management

  • Article

[The feature associated with this page, DirectSound, is a legacy feature. It has been superseded by WASAPI and Audio Graphs. Media Casting have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Media Casting instead of DirectSound, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The IDirectSoundBuffer8::GetCaps method retrieves the capabilities of the DirectSoundBuffer object.

Your application can use the IDirectSoundBuffer8::GetStatus method to determine if the buffer is playing or if it has stopped.

Use the IDirectSoundBuffer8::GetFormat method to retrieve information about the format of the sound data in a buffer. You also can use IDirectSoundBuffer8::SetFormat to set the format of the sound data in the primary buffer. For more information, see Mixing Sounds.

Note

The SetFormat method cannot be called on secondary buffers. After a secondary buffer is created, its format is fixed. To play a sound that is in another format, you must create a new sound buffer with this format.

Memory for a sound buffer can be lost in certain situations: for example, when buffers are located in sound card memory and another application gains control of the hardware resources. Loss can also occur when an application with the write-primary cooperative level moves to the foreground; in this case, DirectSound makes all other sound buffers lost so that the foreground application can write directly to the primary buffer.

The DSERR_BUFFERLOST error code is returned when the IDirectSoundBuffer8::Lock or IDirectSoundBuffer8::Play method is called for a lost buffer. When the application that caused the loss either lowers its cooperative level from write-primary or moves to the background, other applications can attempt to reallocate the buffer memory by calling the IDirectSoundBuffer8::Restore method. If successful, this method restores the buffer memory and all other settings for the buffer, such as volume and pan settings. However, a restored buffer may not contain valid sound data, so the owning application should rewrite the data to the buffer.