Subject: Re: [ecasound] metronome timing accuracy
From: Kai Vehmanen (k_AT_eca.cx)
Date: Fri Aug 22 2003 - 01:47:28 EEST
On Wed, 25 Jun 2003, Carsten Bauer wrote:
> during playing around I tried to put two metronome signals together:
>
> ecasound -t:300 -a:1 -i:null -el:sine_fcac,880,1 -ea:50 -eemb:60,10
> -a:2 -i:null -el:sine_fcac,880,1 -eemb:6,1
> -a:all -o:metro.raw
>
> so one ticks every second, the other every 10 seconds. Interestingly, you hear
> signals go out of sync very soon, looking at the file with ecawave shows that
[...]
> the 6 bpm metronome is a bit slower compared to the 60 bpm one, after 180 sec
> it has 1 sec (~0.55%) delay and thus the two signals sound in sync again for
This was indeed a bug in the pulse gate code. The reason for the error was
loss of precision due to use of float numbers to track current pulse
phase. I converted the code to use fixed-point arithmetic and now it's
100% accurate. Fix is now in CVS.
Big thanks for the bug report!
-- http://www.eca.cx Audio software for Linux!
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