DMA Buffer Size (DMA Buffer Transfer Latency). In some programs you will not only be confronted with the choice of an audio driver, but also with the selection of a so-called buffer size. The underlying functionality is also relevant for topics such as ASIO (this has its own dialog). WDM kernel streaming (see page 35) is also directly affected by this. Although it may appear somewhat complicated at first glance, it is extremely useful when you understand its significance�and it's not really that difficult after all. The number and size of audio buffers determines the speed with which an application (such as a software synthesizer) can access the Windows driver. A smaller number of buffers and a smaller buffer size will ensure that the card responds faster. You will notice this when adjusting the controls of a software synthesizer, for example, or when moving the play marker during playback in a hard disk recording program. You might think faster is better, but there's a catch. The setting is system-dependent and�if the system is too slow�an excessively low value will result in audible dropouts during recording and playback. If you notice dropouts, raise the value.
ASIO. The ASIO button will take you to the settings for the so-called ASIO buffer size. These are responsible for the �speed� of the ASIO driver. A lower number of samples per buffer will reduce the time that elapses before an application issues audio signals with ASIO support. This setting is system-dependent. In the best case, the software will have a latency of around 1.5 ms. On average systems with processor loads typical for a music PC, you can expect values around 7-30 ms. Please note that you may have to restart the ASIO application before you can work with the new settings.
Digital Out. The Settings page of the DMX ControlPanel lets you choose from a variety of sources for digital audio output. The following source settings are available in the �Digital Out� field:
At the click of the mouse: signal sources and S/PDIF filters.
