Q: What`s the difference between DirectSound and waveOut ?
A: Short version: you should use waveOut on win95/98/me/nt4 and DirectSound on win2k/xp/ insert name of future windows OS here .
waveOut is old, outdated API (Application Programming Interface) for playing digital sounds in 32bit Windows OS`s. Old OS`s (all win9x and nt4) have good waveOut implementation; you should use waveOut output on those for best performance. waveOut features are limited; it doesn`t even natively support mixing multiple streams. It appears that waveOut is provided in win2k/xp only for compatibility with old software - win2k/xp waveOut implementation is rather bad, it doesn`t use any kind of hardware acceleration; all mixing is performed by software (may interrupt sound when CPU usage is high).
DirectSound is the new \"modern\" sound playback API, available as redistributable for all versions of 32bit Windows OS`s (though nt4 directsound is terribly broken from my experience). DirectSound natively supports mixing multiple streams, independent volume control, hardware acceleration layer & hardware emulation layer (features which aren`t supported by hardware are emulated by software, so the programmer doesn`t have to worry if his new l33t code will work right on old sb16). DirectSound should be generally fine to use everywhere except for nt4, as long as you have latest DirectX version for your OS and proper soundcard drivers installed. DirectSound is preferred over waveOut on win2k/xp, because their DirectSound implementation is relatively good (eats less CPU than waveOut and is free of win2k/xp waveOut implementation glitches). DirectSound was originally designed to let games utilize hardware acceleration available on your system without having to touch low-level hardware functions directly (like any other component of DirectX).
Ответ: никак (смотри вышенаписанное). Теперь для пущей совместимости с современными играми используется интерфейс DirectSound, который, кроме управления аппаратными возможностями звуковой карты, эмулирует те функции, которые картой не поддерживаются. Тех. прогресс, как правильно отметили выше, не остановишь...