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Question: Does a JSFX EQ plugin that allows users to tweak the Q-Factor up to 15 require ext_tail_size = -1; I learnt a high-Q value can make audio "ring" for a long time after the input stops so ext_tail_size = -1; is required in this case???
Asked by ext-tail-size-1 (102.176.101.x) on June 1 2026, 1:57pm
Reply on June 1 2026, 4:18pm (edited at June 1 2026, 7:07pm):
    ext_tail_size = -1 [edit: this is wrong do not use it] means no tail -- so you should not set ext_tail_size or set it to 0 for infinite. Or you could do something reasonable like srate (for a second of tail, your filter should resolve by then?).

    edit: ok so yeah -1 means "if the plug-in is receiving silence and the output has dropped below this threshold for a while, stop processing it until some non-silence comes in". which should be good for filters. You could also calculate the lifespan of an IIR filter using some fancy math, probably, or iteratively find it when calculating the filter coefficient with less fanciness.

Comments:
  • Posted by ext-tail-size-1  (154.161.254.x) on June 1 2026, 6:27pm:
    I saw the ff in the manual and I thought -1 means it will detect the tail by itself, but u just said -1 means no tail. "If set to -1, REAPER will use automatic output silence detection and let plug-in state settle. If set to -2, then REAPER will assume the plug-in has no tail and no inter-sample state." So I guess I shouldn't use it all even in plugin with high Q Factor and even in delay plugins ???

  • Posted by ext-tail-size-1  (154.161.254.x) on June 1 2026, 6:37pm:
    Also, what happens when ext-tail-size-1  is not written in the code at all? Is that the same as setting it to 0.

  • Posted by ext-tail-size-1  (154.161.254.x) on June 1 2026, 6:41pm:
    The difference between 0 -1 -2 and not writing it all is confusing me. If you could explain on the context of high Q and delays vs plugins that simple like only a gain knob. I want to know when to ignore writing ext-tail-size and when to use -1 0 or -2

  • Posted by Justin on June 1 2026, 7:05pm:
    ah sorry yes, I was mistaken. you can use 0 (the default, the same as not setting it) which means "can produce output at any time", or -1 which will auto-detect silence.

  • Posted by ext-tail-size-1  (154.161.251.x) on June 1 2026, 7:37pm:
    Thanks so much. I now understand.

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