Subject: Re: [ecasound] gates - major change
From: Jeremy Hall (jhall@uu.net)
Date: Wed Dec 13 2000 - 08:13:20 EET
so let me get this straight.
When we do gates now, when the gate is triggerred, frames are written to
the output device. When the signal falls below the threshold, we stop
writing frames. How then do we maintain synch? If enm, for example, is
used, how do we keep from losing continuity?
This should be a switch, not a force-to.
_J
In the new year, Kai Vehmanen wrote:
> I thought this is worth a mention. I just did a very small code change,
> but something which totally changes how gates work. Instead of muting
> the passing audio buffers, gates now truncate the buffers if gate state
> is closed. In the future, -ea + -k combinations will be able to do
> everything that the old gates were able to do.
>
> And IMHO the new behaviour is must for useful. The biggest drawback is
> that you should expect difficulties if using gates in chainsetups where
> you have realtime audio objects (if gate truncates all audio, sooner or
> later you'll get an audio dropout).
>
> But the benefits are clear. You can now easily crop sections of audio
> files, and do automatic volume-based cropping. For instance.
>
> --cut--
> ###| /empty1 |$ ls -la guitar.wav
> -rw-rw-r-- 1 kaiv kaiv 15790124 Sep 30 23:27 guitar.wav
>
> ###| /empty1 |$ ecasound_debug -i guitar.wav -o gate-test.wav -gc:60,1
>
> ###| /empty1 |$ ls -la gate-test.wav
> -rw-rw-r-- 1 kaiv kaiv 180268 Dec 12 22:13 gate-test.wav
> --cut--
>
> This cut the section [60:00 sec -> 61:00 sec] from guitar.wav into
> gate-test.wav. The old '-gc' would have just muted all audio outside the
> [60,61] region. The threshold gate is used similarly:
>
> --cut--
> ###| /empty1 |$ ecasound_debug -i gate-test.wav -o gate-test-rms.wav -ge:11.2,5,1
>
> ###| /empty1 |$ ecasound_debug -i gate-test.wav -o gate-test-peak.wav -ge:5,5,0
>
> ###| /empty1 |$ ls -la gate*wav
> -rw-rw-r-- 1 kaiv kaiv 163884 Dec 12 22:18 gate-test-peak.wav
> -rw-rw-r-- 1 kaiv kaiv 143404 Dec 12 22:17 gate-test-rms.wav
> -rw-rw-r-- 1 kaiv kaiv 180268 Dec 12 22:13 gate-test.wav
> --cut--
>
> In the first one, gate is opened when the RMS-volume goes over the 11.2%
> threshold, and closed when RMS-volume falls below 5%. In the second,
> both entry and close thresholds are 5% (peak volume).
>
> --
> . http://www.eca.cx ... [ audio software for linux ] /\ .
> . http://www.eca.cx/sculpscape [ my armchair-tunes mp3/ra/wav ]
>
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