[LAD] panning thoughts

Rui Nuno Capela rncbc at rncbc.org
Sun Nov 14 16:05:03 UTC 2010

On 11/14/2010 11:27 AM, Paul Davis wrote:
> On Sun, Nov 14, 2010 at 6:18 AM, Rui Nuno Capela <rncbc at rncbc.org> wrote:
>> as said, for qtractor the panning coefficients are computed _only_ when
>> the pan widget slider changes. the simple one-shot calculation is
>> carried out in gui thread context so it does not add a cycle whatsoever
>> to dsp load ;)
> this would suggest that either you don't do panning automation or you
> store panning automation as precomputed values?
> ardour behaves as you described for the case without automation, but
> during automation playback, it does per-sample computation of pan
> positions based on automation events, and this occurs in the audio
> thread(s).

yes, there's no automation in qtractor as of yet. anyhow, panning
coefficients are indeed pre-computed into per-channel gain, which in
turn is applied in per-sample computation, same as ardour i guess. with
or without automation.

when automation gets into the picture, then yes it is in my mind design
that it will have this sin/cos computation re-evaluated on a per-buffer
or process-cycle basis. even though, it's all ordinary cheap for
nowadays cpus :)

rncbc aka Rui Nuno Capela
rncbc at rncbc.org

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