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Speaking of polarity... (APU related)
https://forums.nesdev.com/viewtopic.php?f=3&t=11434
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Author:  Zepper [ Tue Jul 15, 2014 6:04 am ]
Post subject:  Speaking of polarity... (APU related)

In the APU, what are the conditions to output a sample of "silence" (zero) instead of a "volume level" (non zero), including the duty cycles (0 and 1) but as negative and positive?

Author:  rainwarrior [ Tue Jul 15, 2014 6:38 am ]
Post subject:  Re: Speaking of polarity... (APU related)

The initial output is always zero to positive, there's no negative. After this it goes to a highpass filter, which will centre a playing waveform around zero a little bit after its onset, and when it stops playing it will drift back up to the zero line.

Author:  Zepper [ Tue Jul 15, 2014 3:36 pm ]
Post subject:  Re: Speaking of polarity... (APU related)

The idea of +1 and -1 (positive and negative samples on square waves, duty cycles) came from the defunct Nofrendo.

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