AGC - Automatic Gain Control

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steve
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Re: AGC - Automatic Gain Control

Post by steve » Thu Nov 01, 2012 3:09 am

Thunderbolt1000T wrote:It has nothing to do with my machine, since I don't have this problem running similar effects such as compressor, SC4, etc. This plugin is just uber slow.
Thank you for the feedback, but it does not help without some details.

SC4 is a LADSPA plug-in, written in C++
Chris's Compressor and AGC are Nyquist plug-ins.
Nyquist and C++ are very different.

I've just tested a track with both Chris's Compressor and this AGC plug-in. On my Linux machine, Chris's Compressor took 19 second (averaged over 3 runs) and this AGC plug-in took 17 seconds averaged over 3 runs.

I presume that you are not running Linux. There could be some platform dependent performance issues.

The processing time for the AGC plug-in depends partly on the settings, particularly the "Gain Reaction Speed". A faster reaction time time uses a lot more processing.
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Re: AGC - Automatic Gain Control

Post by steve » Thu Nov 01, 2012 3:12 am

Gale Andrews wrote:Well I suppose you could add a distortion control if that's what is needed...
Why not include a distortion effect?
I doubt that many users would think of looking at an AGC effect if they want distortion. They are far more likely to look for (and not find) a distortion effect.
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Re: AGC - Automatic Gain Control

Post by Gale Andrews » Thu Nov 01, 2012 3:13 am

steve wrote:Here's a bad recording:
bad-recording.wav
Try AGC with default settings and you will notice that the "background" noise is greatly amplified.

The "background noise peak level is around -20 dB, so set the Squelch to -18 dB (a little above the noise floor).
The background noise is not amplified as much.

Now set the Squelch attenuation to -30 dB.
The background noise is virtually silenced until the gain starts rising for the start of the music.
Not in your new version http://forum.audacityteam.org/viewtopic ... 19#p194219 , where at a -30 dB setting the background noise before the music is about the same as at -60 dB (which seems more intuitive given the noise is at -20 dB) ?
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Gale Andrews
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Re: AGC - Automatic Gain Control

Post by Gale Andrews » Thu Nov 01, 2012 3:15 am

steve wrote:
Gale Andrews wrote:Well I suppose you could add a distortion control if that's what is needed...
Why not include a distortion effect?
I doubt that many users would think of looking at an AGC effect if they want distortion. They are far more likely to look for (and not find) a distortion effect.
Politics. AGC with intentional distortion is better than Leveller with unintended distortion and can't be called a regression.


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steve
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Re: AGC - Automatic Gain Control

Post by steve » Thu Nov 01, 2012 3:40 am

As Nyquist effects are "below the line", would it not be possible to remove Leveller and squeeze in 2 Nyquist effects below the line?
I think that guitarists in particular would want a distortion effect with a bit more tonal control than just "how much clipping".
We also get a lot of requests regarding vocal distortion effects (robot voices, monsters, airline pilots....)
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Re: AGC - Automatic Gain Control

Post by steve » Thu Nov 01, 2012 4:57 am

Thunderbolt1000T wrote:This plugin runs uber slow in Audacity 2.0.2. Chriss Capel's compressor runs at least 10 times faster, and I'm not exagerating. Any idea why?
It could be due to the amount of RAM being used.
This plug-in loads the entire audio into RAM. If the amount of free RAM gets too low, Windows will start swapping data to the hard drive and the plug-in will be really slow,
How much RAM do you have on your computer? Do you know how much of that is free (unused)? How long was the track that you were processing? Was it a stereo track? What was the track sample rate?

I've tested the plug-in on XP and it is a bit slower than some other Nyquist effects (such as Chris's Compressor) but I did not find that it was unreasonably slow as long as there was enough free RAM.
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Re: AGC - Automatic Gain Control

Post by Thunderbolt1000T » Fri Nov 02, 2012 12:56 am

Gale, yes, I'm still on XP. This plugin shouldn't be as slow as it is on my machine, because similar plugins such as SC4, Audacity's built-in compressor, and Chriss Capel's compressor are much faster. I'm thinking that AGC may require more memory than those other plugins. It runs at least 10 times slower than any of those plugins.

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Re: AGC - Automatic Gain Control

Post by steve » Fri Nov 02, 2012 1:47 am

Thunderbolt1000T wrote:Gale, yes, I'm still on XP. This plugin shouldn't be as slow as it is on my machine, because similar plugins such as SC4, Audacity's built-in compressor, and Chriss Capel's compressor are much faster. I'm thinking that AGC may require more memory than those other plugins. It runs at least 10 times slower than any of those plugins.
There is probably not much that Gale can do about this. He is not the developer of this plug-in.
As I wrote previously, SC4 is a LADSPA plug-in and LADSPA is a completely different type of code from Nyquist.
AGC requires a lot more memory than Chris's dynamic compressorr when processing long audio selections because AGC requires that the entire audio track is loaded into RAM.
How much RAM do you have on your computer? Do you know how much of that is free (unused)? How long was the track that you were processing? Was it a stereo track? What was the track sample rate?
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Re: AGC - Automatic Gain Control

Post by Thunderbolt1000T » Fri Nov 02, 2012 3:14 am

The memory would explain everything, since I only have 1GB of RAM. This plugin would work much better on my machine if the entire audio track didn't have to be loaded into RAM.

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Re: AGC - Automatic Gain Control

Post by steve » Fri Nov 02, 2012 3:44 am

Thunderbolt1000T wrote:This plugin would work much better on my machine if the entire audio track didn't have to be loaded into RAM.
That may be possible, but it's not an easy programming task.
If there is sufficient interest in this effect then I'll look into that, but I'm not inclined to spend a lot of time on it if there is no interest.
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