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OPL emulation

4 bytes removed, 10:05, 25 June 2016
OPL chips
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Stereo was introduced by dual OPL2 cards. There, one OPL2 core was used for sounds on the left, the other for sounds on the right. Sending instructions to both cores at once resulted in center sounds. The OPL3 core was the first to properly support stereo in the chip itself (though again limited to three panning positions of left, right, and center); but the need for backward compatibility meant that by default, it emulated a dual mono OPL2 setup, and a specific instruction had to be sent to set it in OPL3 mode proper.
The waveforms available are as follow:
#Logarithmic sawtooth wave, or derived square wave, available in OPL3. This is actually the result of an exponentiation by a negative number.
Waveforms are then combined either by simple addition of the output of both operators, or by using the waveform from one operator to modulate the frequency phase of the waveform from the second. The FM method is the one that offers the broadest range of possibilities. OPL3 chips can combine two channels to turn them into a single channel with four operators, greatly increasing the possible combinations of addition and frequency modulation available for each sound.
==OPL emulators==