AGC v2.0 plugin

eyagos

AGC v2.0 is finished, and you have it here:

http://ciberia.ya.com/eyagos



AGC, as many of you know, means Automatic Gain Control. AGC's circuits are widelly used as parts of many analogic and digital circuits: Amplifiers, radio tuners, radars, wireless cominications, industrial applications, etc etc. This one, as most of you can supouse, is designed for audio hearing. His functioning is very simple:

1.- Reads input Level.
2.- Compares it with a reference value (the reference is -3dB)
3.- If Level is greater than -3dB, it aplyes a little negative gain each 1 sample cycle (practically instantaneous). After a few samples (50 or 100), gain should be reduced to -3dB exactly.
4.- If Level is lower than -4dB, it aplyes a little positive gain each 1000 samples cycle. So, it takes much more time to increase gain to -3dB than to reduce it to -3dB. (if not, the invent would not function). The value of 1000 samples can be adjusted to control the speed (or the Slowness) of the algorithm.
5.- But if Level is even lower than a certain Threshold(in example -40dB), the gain will not be increased. This should prevent gain to increase too much -or indefinitelly- when input is very low (noise) -or there is no input-.


The plugin is perfect for hearing Internet music. If you have a TV card, this plugin can "eliminate" differences between different channels. It can be used too for hearing mp3 or CD music, although you must take into account that AGC can change the dynamics of sound (even changes in the same song). To reduce this, sets slowness control to maximum.

And one last recomendation: Don't use more than one plugin in the same circuit, and put it allways at the end of the circuit.

radiocolonel.it

... what a cool surprise today!!! i was looking for an AGC from long time... no words to say thanks! I just tried a bit and it seems great, audio quality is really good and now i'lsee how to make it work with my mic.... i'll tell u how it behaves.
Thanks again!

Lex Nahumury

Great tool eyagos. I've always liked your AGCs!

/LeMury

Russ

Pretty cool eyagos. I was just trying out out with some mp3's and it works great. I have a question though. What does it do, when it has no signal? It seems to hold the value from the previous signal. I wonder if it would be better to default to a midpoint value, or maybe even a little higher, to make it respond a little qucker to lower level signals. i.e. Going from straight music (especially if it lowers the level), to a low level source (voice only, etc), it takes a couple of seconds to bring the level up to an audible level (especially if there are pauses in the talking, etc).

For example: If a play a low level source, where the AGC Monitor shows around +20 to +25dB for the average gain, and then stop the signal. The AGC holds at around +20 to +25dB. So if I then play the same signal again, it is instantly audible. However, if I play a signal with a normal level (or higher level), and stop the signal, it holds at a much lower level, so if I then play a low level signal, it takes longer to bring the level up to an audible point (when listening at a low volume). I would like to see it more responsive on the low end if possible (maybe have it expect the signal to be low when it has no input, as it responds quicker to higher level, and thus can compensate quicker if the signal turns out to have a higher level). i.e. I imagine using the AGC for night time listening. I set my volume to a level where it will not disturb other people, but at the same time I want to be able to hear the quieter parts (parts that may be just barely audible, at this volume level without the AGC). As it is right now, the time that it takes to bring the lower levels up, I miss parts of the lower level audio (with the AGC slowness setting at zero).

Another option might be to allow us to set the nominal level, so that in situations like this, we can turn up the volume, so that it is at an optimal level for the lower end, and then set the nominal gain lower, so that the higher level sounds are still not too loud, etc.

Anyway, it is just an idea, and like I said, without the AGC some of these audio parts are just barely audible (at lower volume levels), so it allready helps with that in a big way. I am just wondering if it is possible to make it more responsive at the lower levels, without losing the responsiveness at the higher levels.

-Russ

eyagos

Russ, this plugin tries to adjust the level of input sounds at a confortable and constant average level (I say averge level, because a constant level is 'no sound'), but not changing the original 'dynamics' os the sound. So, it reduces gain very quickly (no average is made here) if input sound level is too loud (it prevents clipping), and increase gain very slowly (with a long averge) if input sound is too weak.
If you want to hear the quiter parts of a song or a movie louder, you should use a compressor. Try presset "Normalizer" of Dynamics Processor, and adjust the times at your taste. This could be more efective too for microphone uses, radiocolonel.it.

The Threshod value is used to avoid anoying situations.
The worst case would be this: You have AGC plugin conected, but you are not playing any sound. If threshold parameter would not exist, AGC will increase gain to the maximum (I have not tell you before, maximum gain is +60dB). If you now plays any sound at a normal volume, it should sound at +60dB until AGC could reduce the gain (it is done very quickly, but not instantenously).
Other bad situation, if you'll not had a threshold value, will be when you have a mic conected and not registering any sound: The noise floor (lets say it is at -50dB) would be amplificated. If you use a threshold value of -40dB, the plugin will not increase gain.
Well, these anoying situations are eliminated with a threshold value. But as you has said there is still a problem: AGC can mantain in memory a gain value too high, calculated from the last music. This problem could be controled with a new parameter that set the maximum gain that AGC can aply: Let's say, you don't want more amplification than +20dB... Well, this can be a good idea.

LeMury, as you can see this version can increase and decrease the volume. I think that it is a real AGC now.

Thank you guys.

Russ

Good stuff. I used to have a Phillips TV with SMART sound, and it was a great feature. I was looking for something that works similair to that. I will check out your Dynamics Processor, and see how well that works.

-Russ

Lex Nahumury

Yes I noticed. 'Threshold' and 'Gain Increase' are valuable additions indeed.
Very clever and usefull tool in cases where one needs constant average volume
but without compression.

/LeMury

Matti

Have I done something wrong as I can´t get AGC work with latest "h" driver; the user interface doesn´t open etc. I had it working but after new installation it doesn´t.
Regards Matti

Matti

What the heg, No problems now! (shit happens when You are tired)
Thanks again! Matti

rajder

is there version for 3537 ?

Chester01

Can you possibly recompile the agc.kxl for 3538j I can load the plugin, both agc.da and agc.kxl register but i cannot load the plugins interface... Thanks!

Russ

Which version did you download. The 3538i version should work with 3538j (works for me).

Chester01

3538i is the version i have (of agc 2.0) and the 3538j driver

Russ

It is actually version 2.1 (from the microcode comment), but again it works for me in 3538j, so I am guessing that something else is causing the problem.

Maddogg6

Confirmed - it works for me as well.

Maddogg6

Oh - DONT register the DA - I think I only register a single KXL file...
Im thinking registering the DA messed you up...

Chester01

how can i unregister and reregister the plugin?

Maddogg6

There is registry entries that can be deleted... (I cant remeber the location)

or, do a global reset - but that removes all added plugins - IE puts KX back to fresh installed state, so youd have to re-resistar all other plugins as well.

Chester01

global reset worked, just had to reload the plugins i use... Thanks for your help

imperia

can you make AGC work with 3538l?

knight23

can you please post the AGC algorithm. thanks!

smyle

*bump*

Chiltn

I still can't get the interface to work...I'm running the 3538m, but I'm about to try the new 3539...anyone tried AGC with it?

Cheers!

silvertones

Is there a version for 3538m

BuzzT

Is there a version of the Automatic Gain Control V 2.0 for 3541 available? I had problems to install it since 3538.

TravelRec.

You can use "Dynamics Processor" instead, it´s bundled with the driver.

pkozerski

This is my up
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3541 with many plugins, AGC is also there and it works ok with 3541