What's New in DirectSound

The DirectSound application programming interface (API) has not been significantly revised for DirectX 9.0. However, many performance enhancements have been implemented.

In addition, the following changes have been made:

• The maximum frequency of sound buffers has been increased from 100 kHz to 200 kHz, where supported by the operating system. (These higher frequencies are not supported by DirectShow.)
• Frequency and effects controls (DSBCAPS_CTRLFREQUENCY and DSBCAPS_CRTLFX) can now be combined on buffers. Combining these flags makes it possible to have Doppler shift on buffers with effects.
• Audio formats described by the WAVEFORMATEXTENSIBLE structure are fully supported throughout DirectSound.
• The standard effect DMOs can process audio data in WAVE_FORMAT_IEEE_FLOAT format.
• The standard effects support parameter curves (when hosted outside of DirectSound) without having to call IMediaObjectInPlace::Process on them repeatedly in very small increments.