Advanced Panasonic GH2 Tutorial: Setting Audio AGC in PTool

My previous GH2 tutorial catered to people just getting into using PTool to modify settings for their Panasonic GH2 (and get much better video quality in the process).

This next tutorial is more like “the story so far” in terms of ongoing testing. It caters to advanced users already familiar with PTool and looking to modify the gain options beyond what the factory settings allow.

I suggest reading the “GH2 Audio Hacks” thread I started at Personal-View.com last year before proceeding further.

Here’s a glossary for reading the data below.

dBFS = deciBels Full Scale

AGC = Automatic Gain Control

Hexadecimal = A counting system based on 16 instead of 10, with eleven through 15 represented by the letters A through F.


Updated: 2012-03-07

Here is the new (decimal value) PTool data gauging the peak noise level of the camera when a 2.5mm cable is plugged in but no device is connected.

Note that the same value may go +2/-2 dBFS in noise for each test, depending on the fluctuations – this is not a “clean” environment test but just intended to home in with broad strokes.
Tests were done using Panasonic Firmware version 1.1 and PTool Version 3.64D

 

Test 1

AGc 235 -72dBFS  (HEX EB)
AGC 203 -71dBFS  (HEX CB)
AGC 36 -62dBFS  (HEX 24)
AGC 14 -52dBFS  (HEX 0E)

Test 2

AGC 203 -72dBFS  (HEX CB)
AGC 192 -70dBFS  (HEX C0)
AGC 176 -67dBFS  (HEX B0)
AGC 160 -60dBFS  (HEX A0)

Test 3

AGC 160 -60dBFS  (HEX A0)
AGC 144 -52dBFS  (HEX 90)
AGC 128 -46dBFS  (HEX 80)
AGC 112 -72dBFS  (HEX 70)

TEST 4

AGC 112 -74dbFS (HEX70)
AGC 96 -72dbFS (HEX60)
AGC 80 -72dbFS (HEX50)
AGC 64 -70dbFS (HEX40)

 

Remember, those first numbers are the decimal versions of the numbers.

That’s the format you enter them in.

But the ones to pay attention to, are the resulting hexadecimal numbers they get converted to (the top 2 boxes out of the 4 at the bottom in PTool in the earlier graphic). 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 limited 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). Also note how unpredictable the dBFS values become for decimal numbers below 112.

 

Files for advanced testers below (you know who you are).

Per_Lichtman-Andy_Hunter-Escalation_(MIC_LEVEL_1)thepalaliasV2

Per_Lichtman-Andy_Hunter-Escalation_(MIC_LEVEL_1)FACTORY

Per_Lichtman-Andy_Hunter-Escalation_(MIC_LEVEL_4)thepalaliasV2

Per_Lichtman-Andy_Hunter-Escalation_(MIC_LEVEL_4)FACTORY

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