If something is unclear I usually connect headphones to the Lilliput and hit play in cam. Then you can at least check after recording if anything went wrong.

if audio going directly into camera is now decent quality with the hacks, why bother with the tascam or h4n? why not just get a beachtek preamp and go directly into camera?

re9d, the high numbers are actually the low gain settings, 235 is almost inaudible.

@re9d Remember, those numbers are the decimal versions of the numbers.

But the ones to pay attention to when you are modifying are the hexadecimal numbers they get converted to (the top 2 boxes out of the 4 at the bottom in PTool). These numbers all start with "0x".

All of the values I've provided read "0x00__" where the "00" is an attempt to turn off (or at least reduce) the "automatic" part of the "automatic gain control". Also, in "0x00__" the "_" is the two digit number the gain is divided by (at least that's the working hypothesis so far based on the testing I did months ago).

At the higher values (such as 235) it seems it may attenuate the input signal (though this will not keep an overly high input signal from clipping).

If you want to see my AGC value tests so far, here's a blog post I'm working on regarding the topic.

http://perlichtman.com/pasdenapulse/wordpress/2012/03/06/advanced-panasonic-gh2-tutorial-setting-audio-agc-in-ptool/

@palalias Thank you! I used the values from your blog´s "Test2" : 203/192/176/160. Patched them with Orion 4D vC. With 448000bps, I had severe glitches, 348000bps works fine.

192 fits my needs with 0dB (full analog scale) at the mixer´s -34dBu mic level output. No difference with 192 to 176/160, seems like the GH2 limiter kicks in at-6dB headroom.

Very interesting: The GH2 ´s reaction to smooth volume changes with a steady signal, a 1000hz sine from the mixer´s built in tone generator. The attached sreenshot displays a length of about 7 seconds. In the middle, around 3 seconds long, you notice -and hear- a stairstepped reduction of volume.

This happened when I adjusted full scale from my mixer

(already attenuated in GH2 I guess, that´s why the waveform is not higher on the left side)

down to around -3db analog level and then up to 0dB analog level, my reference for testing. This is an analog mixer, so I would expect a smooth curve but you see steps. This curve spans 3 seconds. Don´t know wether this is the results of 16 bit quantisation (I don´t think so) or automatic gain messing up... All the best, Frame

Btw, I'm diving into testing the meters now, too.

Also, note that (for the internal mic) the 203 setting does let you reach 0 dBFS using real sounds. Try clapping really close to it, for instance. Will report back on using external sources later.

@SpaceWig

As I mentioned in my latest posts, using sine wave tests has given some errata so far. If you start the signal at a fairly decent level and test it, the results are entirely different than if you start it at a low level and fade it up to the intended increment. For this reason, I'm leery of using the standard sine wave tests until I can rule out the possibility of them creating further problems.

If you look at my blog at http://perlichtman.com/pasdenapulse/wordpress/2012/03/06/advanced-panasonic-gh2-tutorial-setting-audio-agc-in-ptool/ you can see the "noise floor" tests, though several new values I tested today have not been added yet.

Due to some unpredictable camera behaviors, the testing process is really a lot more trial and error than one would hope and it's been easy to make "false progress" along the way using the "more scientific" methods I would prefer to rely on.

However, I'm in the process of calibrating the camera meters to make it easier to test things. Today really saw things move forward a lot so keep your eyes peeled.

@thepalalias: It was at 192. I will try to prepare some test signals in my DAW to feed the GH2 with raising or falling tesstones.Sines and white noise. But why not testtones? Imagine you record a distant city, a creek, rain, your fridge, ventilation, these are all steady signals with slight variations in volume according to the mics movement...

@spacewig

As I've mentioned earlier, it certainly appears that it does. However, mapping the nature of that behavior is not a priority for me since it has not been affecting real world recordings in the same way (including ones featuring sustained passages of high signal levels).

In the first page of the thread I discussed the efforts to bypass the compression/make-up gain and how the values currently being used (203, etc.) exhibit the least compression of the values tested so far. The four digit part of the hexadecimal number that can be modified seems to apply heavy compression/make-up gain if values other than "00" are used in the first places.

If you have read up on the discussion so far and don't have to worry about repeating steps already handled, I would appreciate any time you'd be willing to put into the experiments you described. For my part, I'm reluctant to continue in that vein because my current efforts are focusing on field-testable results rather than clinical trials.

One of the reasons for this is that (while unlikely) it is nonetheless possible that the waveform analysis that the GH2 is doing prior to AGC processing might have more wrinkles than the threshold, knee, etc. of a standard single-band compressor. If it turns out that there is any sort of multi-band analysis, or other methods being used to identify certain patterns to activate stronger ducking or gating behaviors, or even simple side-chain filtering, etc. going on, then I would end up having to spend a lot of extra time analyzing additional variables.

By focusing on the way it handles real-world signals (rather than synthetic ones) as well as self-noise and ambient room noise, I can increase the chances that my results are translatable into actual use, even if there turn out to be any (admittedly less likely) additional wrinkles.

@Frame Sorry, I almost forgot to address your comment about 192. The reason I mentioned 203 as opposed to 192 is that it seems to measure as having a (very slightly) lower noise floor. The results with 192 were the same: I could still get to 0dBFS when doing real world recordings with the internal mic (meaning that the compression/level adjustment/gain compensation won't always prevent it at that setting).

I mention that because of your comments about limiting at -6dBFS.

Thanks, I look forward to the results of your testing. :)

Here are a couple additional notes to help testing.

• The audio meters when using the external input will show different values before you hit record and after. The compression that prevents reaching 0dBFS has so far only been showing up after.

• The above compression issue has shown up in several line in tests at various volumes, but has not shown up when using the Rode Mic VMP plugged into the same port, even when percussive patterns were used in each rather than sustains.