You can determine which objects will be played from memory and which ones will be streamed from a hard drive, CD, or DVD. When media is streamed from the disk or hard drive, you also have the option to avoid any playback delays by creating a small buffer that covers the latency time required to fetch the rest of the file. You can specify the size of the buffer so that it meets the requirements of the different media sources, such as hard drive, CD, and DVD. Unlike the rest of the streamed file, this small buffer is actually stored within a SoundBank and loaded with the SoundBank into memory at the appropriate point in the game.
Audio playback in Wwise is always streamed regardless of whether the streaming options have been selected. The Stream settings, therefore, only apply when generating SoundBanks, and playing back from a remote platform or game.
To stream a sound:
Load an object into the Property Editor.
Select the Stream option.
The Stream options become available.
Select the Zero Latency option to have no delay from the time the object is triggered to when it is actually played. To achieve zero latency, a certain portion of the beginning of the data file must be stored in memory to cover the latency time required to fetch the rest of the file from the media.
In the Prefetch length text box, type the number of milliseconds of the data file that you want to store in memory.