Tutorials and Topics - Peabody Computer Music

Audio I/OAudio input andoutput with MSPThe Play Through checkbox just under the Input Volume slider lets you choose whetheror not the input device is ‘monitored’ directly through to the output. When playthroughis enabled, the dry signal from the input source will play through to the output mixed inwith any processed signal you may be sending to the output in MSP. Disablingplaythrough will enable you to control how much (if any) dry signal from the audio inputis routed to the output.This option can be changed in MSP on Macintosh by sending a message to the dsp objectto change it. Put the following in a message box and clicking on it will turn playthroughoff:; dsp driver playthrough 0Using an argument of 1 will turn it on.The Input Section allows you to select the Input Source (for example Line or Mic input forthe selected device) as well as the sampling rate and bit depth in the Current Format popupmenu. Similarly, the Output Section also allows you to select the sampling rate andbit-depth in its Current Format pop-up menu. The available selections will vary,depending on your audio hardware.You can set the volume levels for the individual audio input and output channels, muteindividual channels, and/or select them for playthrough using the controls located belowthe Current Format menus. The lower part of the window is used to display the currentinput and output settings.Using MME Audio and DirectSound on WindowsThree types of sound card drivers are supported in Windows —MME, DirectSound andASIO. Your choice of driver will have a significant impact on the performance andlatency you will experience with MSP.The MME driver (ad_mme) is the default used for output of Windows system sounds,and are provided for almost any sound card and built-in audio system. Whilecompatibility with your hardware is almost guaranteed, the poor latency values you getfrom an MME driver make this the least desirable option for real-time media operation.DirectSound drivers, built on Microsoft’s DirectX technology, have becomecommonplace for most sound cards, and provide much better latency and performancethan MME drivers. Whenever possible, a DirectSound driver (ad_directsound) should beused in preference to an MME driver. Occasionally, (and especially in the case ofmotherboard-based audio systems) you will find the DirectSound driver performs morepoorly than the MME driver. This can happen when a hardware-specific DirectSound48