Direct Audio RouTines (DART) Interface

OS/2 multimedia provides application developers with a number of choices for playing and recording audio files. They can:

• Open the waveaudio device
  
• Open a memory playlist and use operation codes
  
• Use the direct audio interface of the ampmix device

The waveaudio device provides an easy-to-use interface that works well for applications with simple audio requirements. However time-critical game applications usually demand a faster response time than the waveaudio device can achieve, because of the device-independent layers of software between it and the audio device.

The memory playlist method of audio playback and recording reduces some of the system overhead that the waveaudio device incurs, because the playlist can stream audio data directly from application memory buffers to audio device buffers. But the playlist is not the ideal solution when precise buffer flow control is needed.

The Direct Audio RouTines (DART) interface for the ampmix device enables games and multimedia applications to bypass the waveaudio device entirely and communicate directly with the amp mixer. Using this interface, applications get the high-speed audio response they require, while remaining compatible with existing OS/2 multimedia applications. Because DART uses the media control interface (MCI), applications using DART can share the audio device with other applications simply by processing the MM_MCIPASSDEVICE message.

DART offers the following advantages:

• Preallocation of user memory 
  No threads
  
  Function pointers instead of API
  
  Time-critical notifications
  
  Tailorable number of buffers

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