How Do I Make a Sound Fade Out Smoothly without Popping?

Pops are caused by a sudden change in amplitude. A pop can occur if you call StopInstrument() when an instrument is still sounding, or if you set an amplitude or gain knob abruptly to 0.

To avoid pops, you need to smoothly change the amplitude from full amplitude to 0 over at least 10 msec to eliminate the pop. This can be done in two ways:

You can call TweakKnob() rapidly in a loop. This ties up the main CPU but does not require any special DSP resources.
You can use an instrument that generates a slowly changing value such as envelope.dsp.

For More Information

See Audio Folio Calls, in the 3DO Music and Audio Programmer's Reference for descriptions of the calls.

See Instrument Templates, in the 3DO Music and Audio Programmer's Reference for descriptions of the instrument templates.

See the example file ta_nopop.c. This example program can be obtained from the 3DO InfoServer.