Stereo Tool

This is still not working properly in the AGC.

Ideas after chatting with Bojcha:
- Dynamically adjust 'Remove remaining peaks' level (move up during more dynamic input, move down during more constant or lower level input). (my idea)
- Compressor after that AGC that backs off when more dynamic input arrives (Bojcha's idea)

This should probably look at the input BEFORE the AGC (although I'm not really sure about this yet).

Output Level at Target add a control to set a window in dB. This window makes the AGC level ignore changes in this respect to the Target Level Ouput, with this effect is diminished enough that unnecessarily increase or decrease the gain, the remainder being absorbed by the rest of the process chain.

Another idea is to use the AGC according to the diagram attached image.
Further details on the following link http://www.rane.com/note155.html#apm1_4

This causes the AGC output level after the target output level function as a compressor.

These are ideas to add ...

_________________
by GAP
"Less is More" (Bob Katz)

Eeeh,

In mijn beleving mag een AGC helemaal niet op spikes reageren ?
AGC is over het algemeen slow attack / slow release, bedoeld om de gemiddelde content op een ingesteld niveau te brengen.
De uitgang van een AGC sectie moet in mijn beleving zo dynamisch mogelijk zijn, de AGC moet dus eigenlijk onhoorbaar zijn en er voor zorgen dat de multiband sectie gelijk ingestuurd word.

De beste AGC (in mijn beleving) is gemaakt door Inovonics op basis van een PWM methode (pulsbreedte regeling)
Onhoorbaar, en toch goed regelend.

Groeten Jeroen.

_________________
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AIRCHAIN-GURU professional independant airchain consultancy.
Orban/Omnia/Vorsis/DSPX/Aphex/Inovonics
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You are right (that an AGC should not handle spikes), but there must be _something_ that does, otherwise the audio goes into the Multiband section at a much higher level and also come out louder at the end.

Ideally, if you could look foreward infinitely, if suddenly the audio level increases a lot that increment should be (nearly) completely removed, or at least it should be played at the same level from the start on. In other processors, a (singleband) compressor is placed after the AGC to fix this (as pointed out to me by Bojcha).

That's probably not real AGC behavior, but it's needed to get a consistent output level without huge spikes if something loud kicks in. The problem here is that in some cases there are only short bursts of loud sounds (a very dynamic bass kick for example), and you cannot look ahead so when it arrives you cannot be sure what it is. That's what makes things difficult.

Hans,

Ill advise you to take a look at inovonics 260 singleband AGC compressor.
It handeles every kind of content without artifacts.

http://www.inovonicsbroadcast.com/wp-co ... Manual.pdf

A complete description of the machines functions is explained in the manual.

Kind regards,

Jeroen.

_________________
----------------------------------------------------------------------------
AIRCHAIN-GURU professional independant airchain consultancy.
Orban/Omnia/Vorsis/DSPX/Aphex/Inovonics
----------------------------------------------------------------------------

I agree with Jeroen.
I think these situations are not normal in recorded music, if it could be live.

This could be caused after a very low passage of a subject and then a sudden blow, under this situation the gain of the AGC should have been gated and well ajueste speed descent, the remaining peak should be absorbed by the rest chain (MB, clipping, limiter, etc..) because time is very short.

I do not see that there may be situations where this phenomenon is very repetitive in a song.

In my opinion, the AGC must be something subtle, to maintain the level of the MB, but that does not change the dynamic too.

At the current AGC, add:

- A control windows, where they set a value in dB in about the Output Target, so the profit is not modified. Does not change the gain to small variations.

- An intelligent control that makes the gain of the AGC, re-configurable value to missing audio or when the AGC is gated. This sets the AGC for possible sudden rise of the audio.

- A compressor transfer function with configurable ratio, when the level exceeds the Output Target. To accommodate any remaining peak.


Well I hope not to be boring.

PS: For the remodeling of the MB, it would be good to add a limiter before the MB MB clipper, helps control without reaching peaks remaining cut it off and decreases the action of the clipper.

_________________
by GAP
"Less is More" (Bob Katz)

I will probably remove the MB clipper altogether, because in the new design it should not be needed anymore.

The current AGC already responds dynamically to small and large volume differences; if they are small the AGC barely moves. So I think the behavior that you are describing is 'kinda' there already.

For examples of sudden HUGE spikes in tracks try for example Leif's torture test a few seconds before 33:00 - those situations are VERY problematic (not just for ST, actually most Orban and Omnia boxes do a much, MUCH poorer job at this).

The Omnia 9 handles this very well, probably because it does (!) have a compressor just after the AGC (displayed in the same output bar!) and it has a bigger look-ahead time (around 500 ms vs. at most 96 ms in Stereo Tool - at least that's the total Omnia 9 on-air delay, I'm assuming it uses all the information to steer the AGC and compressors).

1st > no "singleband compressor" used. - 2nd > "singleband compressor" = ON
http://www21.zippyshare.com/v/63609360/file.html
about 80% Fixed burst! Minimal "punch holes" for other tracks.

edit:
Hans mentioned that track, here's that too..
http://www15.zippyshare.com/v/40068358/file.html

It is good news clipping remove MB and only leave the final stage.

Regarding the AGC, I understand that the control of "push up near minimum strength reduction" drive the speed gain when a signal is very weak and leads to the desired level more quickly than normal. What I do not know which is the control used to adjust the speed of small changes of the signal or is automatic?

I think then that with a compressor at the output of AGC or compressor behavior by the AGC after the Target Output Level is enough to override any remaining peak, or any occasion such as the example.

500 ms, is too ...

_________________
by GAP
"Less is More" (Bob Katz)

Working on something that looks very promising. NOT a compressor after the AGC, but something internal in the AGC, because the AGC knows the difference between a sudden burst of audio and loud spikes - a compressor would not.

This makes it possible to act ONLY in case of those loud bursts, and do nothing at all when there's audio with a lot of dynamics.