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GH2 Audio Hacks
  • 302 Replies sorted by
  • valdi99valdi99
    @thepalalis
    I didn't measured, but don't think I had +20dB or so, as I did set playback loudness on H2n as low as possible. But GH2 was clipping and lightening up reds even at the lowest Audio Level 1 (unhacked AGC0=34). At Audio Level 2 (hacked AGC1=203) it was as I have described above. Any advice what to do? I was palnning to feed GH2 mic input with line-out (headphones) signal from H2n.
    By the way - the attached test signal file is pure wav made by RightMark Audio Analyzer (http://audio.rightmark.org/manifest.shtml).
  • valdi99valdi99
    ACG0=235 does not work properly. I was able to record sound on GH2 from line-out of my laptop, but recording was quiet, although the level indicators were OK.
  • thepalaliasthepalalias
    @valdi99 Headphone outputs can be pretty hot, so we'll need to find you a good value between 203 and 235. I just want to make sure that 235 does not have any audible distortion on it for you before I get started. Is that correct?

    I didn't read carefully enough what you wrote earlier - getting your input test file by itself doesn't help me. What would help me is the addition of the output recordings 203 and 235 that you made using that test file so I can gauge that against the gain differences with the settings I use.
  • thepalaliasthepalalias
    @Tomaso I'll grab a value for you when I'm doing the testing for a good value between 203 and 235 as well.
  • valdi99valdi99
    @thepalais - OK, I will do a comparison and try to place it here. I've attached my test file so anybody could use it, because I think is a pretty good input source, having a calibration tone and some good harmonic sounds. This file is generated & used by RightMark Audio for testing different hardware/players.
  • stoneystoney
    @valdi99 There is no right or wrong value for the audio setting. You just gotta find settings customized to your needs. When you get a new audio device, you'd need to repeat the process.
  • valdi99valdi99
    Well, my goal is to feed GH2 with live audio from H2n line/headphones-out. I had to go down with volume on H2n to 25 to avoid clipping and red on level meter of GH2. And at ACG1=203 my GH2 recorded the above test signal, but with peaks around -25dB... I kept level meters just before they turn to red. So you can't rely on these level meters! And it seems right to me, because if we've changed values responsible for AGC- level indicators "don't know" about these new values, am I right..?
    PS. I am sorry if I sound dumb, but English is not my native lang. and the more so technical audio aspects are somehow new to me.
  • thepalaliasthepalalias
    @valdi99 Changing the values for the level meters is something that we really should experiment with more, if we plan to use them reliably, but they have a dedicated section in the tool. The point of the first two hex values of the AGC is not for that - at least that's what several hours of my own testing showed initially. The first two hex values seem to be for adjusting the "automatic" part of "automatic gain control".

    Regarding the level meters, they are definitely set a bit conservatively by default. They are useful for avoiding clipping during recording (as long as you've already tested to make sure you aren't hitting the mic input too hard) but they are not useful for this type of testing.

    My suggestion is to make a series of test files where you notate the settings you use, and completely ignore the level indicators while you make them. Then, when you get back to your computer, look at what settings produced the output level you preferred.

    Or you can wait until someone on this thread comes up with better settings for the level meters, but I can't guarantee how quickly that will happen.

    I know my own week got slowed down by the Santa Ana winds and a subsequent mild electrocution in conjunction with the fuses when the power came back on, but hopefully things will be back on track again soon. :)
  • TomasoTomaso
    @thepalalias
    Thanks! I will test both the values you find between 203 and 245 as well a the 203 and 36.
  • stoneystoney
    @thepalalias Hope you are doing fine.
  • thepalaliasthepalalias
    @Tomaso No problem.

    @Stonebat Thanks, I lucked out and have been in surprisingly good shape. It was a very fatiguing experience, but I'm pretty much back to normal by now. :)
  • meemee
    @thepalalias, I very belated No problem : )

    I have to start using the H1 more often, I carry it in my camera bag, with the plan to use it, but I have been so into my new GH2 that I keep forgetting. I used it awhile back with my wifes little cannon for some video projects which I still need to sinc up. I will try to post one here, and post a comparison with the GH2 audio hacked compared to the H1 audio too in the new future. Right now I am busy making Halloween and Christmas DVD's for friends and family. Obligations meh. : P
  • valdi99valdi99
    Browsing the net, I've found that typical H2's recorders output is around -10dBv while the typical DSLR external mic sensitivity is around -50dB what makes a 40dB difference. So I have decided to build L-pad attenuator of around -25dB. Would anybody please point me some wiring diagram and what resistors value do I need? Unfortunately there is no exact specification regarding the resistance of both devices input/otput (H2n & GH2).
  • valdi99valdi99
    Wow! It seems that after fw upgrade, GH2's external mic sensitivity is finally correct. Fed from H2n headphone/line-out works fine at Audio Level set to 2. Previously (before fw update) I had problems with same settings on GH2 and H2n.

    Now in audio editor it shows peaks around -12dB instead of clipping and distortions! I am really glad, no need to make any attenuator!
  • stoneystoney
    Nice!!! Thanks for finding it out.
  • valdi99valdi99
    I did some measurable tests and generally speaking - external mic input seems to be now MUCH better calibrated than before!
  • chrimsbroomechrimsbroome
    @anyone, any chance the Ptool hack can increase the bit rate for the audio. Anything greater than 448 Kbs that is being used in the hack at the moment?

  • Vitaliy_KiselevVitaliy_Kiselev
    @chrimsbroome

    You really do not need such bitrates. 192kbps is perfect.
    It looks like all AC audio encoder is restricted at 448bps in Panasonic cameras.

    You can ask @LPowell, as it knows about Dolby encoding very good :-)
  • mozesmozes
    I came across a standalone application, perhaps some one here can use it.
    it is DualEyes, its sync audio automatically with the audio of the video from dslr.
    there is a Fully-functional, 30-day free trial
    singularsoftware.com/dualeyes.html
  • chrimsbroomechrimsbroome
    @Vitaliy_Kiselev ya know we should me meet up for a drink and have a big debate over it.

    Na just kidding I was just speculating.
  • RicochetRicochet
    @thepalalias I have the Rode VM that I'd like to use plugged straight into the GH2 using hacked AGC settings you've been working on. I was thinking of buying the VMP but seeing as +20db gives distortion (which is the setting VM doesn't have), is there any benefit to using VMP over VM (aside from smaller size)?

    Also, I occasionally use my Sennheiser wireless mics plugged straight into the GH2. Has anyone experimented with AGC setting when using the Senns?

    Many thanks!
  • valdi99valdi99
    Would anybody please check-out if remote (wire or wireless) after fw update now wakes up GH2 from econo mode? Maybe Pana has fixed it without a word, just like a mic input..?
  • goofy23goofy23
    this is a very interessting thread, thanks for all this informations.
    Still waiting for my GH2 to arrive, but one question, as someone may have experiences with it.
    Did someone tried to split the input and connect a wireless G2 and a VMP on right and left channel (2 different sources/devices) directly in the GH2 with a splitter?
    If, with which settings, would be interessting to know, so no real need for a external pre anymore in some configs.

    Someone asked before for seperate regulation, the 2 channels cant be regulated seperately and i guess this will never be possible?

    What i really would love to see too is a headphone out over the AVout while recording (of course).

    As far i understood we can change the digital gain (beside AGC range) but are not able to set the GH preamp to 1:1 Gain ratio so he only works as a audio buffer and not as a amplifier, it seems there is always some gain on it?
    As users reported distortion even with low 203 settings, means the pres GH2 are over their limits, no digital lowering will help.

    On the other hand last posts reports that the 1.1 firmware is able to handle consumer line signals (-10dB), which isnt bad at all, without any distortion, which implies the GH2 Pre is 1:1 then?

    (damm also a bit cluttered post, sorry i will get better with the time)




  • madrendermanmadrenderman
    now i start to record audio with camera, and i found some problems...
    my rig is a NTG2 rode -> beachtek DXA-2s -> adapter 3,5mm to 2,5mm
    actually i have some random problem with adapter, be cause gh2 sometimes not recognize external mic, or if i push strong adapter, reiceve an input like external remote, and start to record, or stop to record!!!
    i know that the chain without adapter work fine (i used it with other cameras until last week).
    i'm feared from two things :
    1) i can't check audio in, be cause gh2 not send audio out from hdmi or analog connectors during recordin (Vitality have you chance to enable audio out somewhere during recording?)
    2) if there is some movment of cable i risk to see stopped the recording.

    and last, but not least... mic in seems rich of noise. Probably is my adapter 3,5 to 2,5 be cause i connected beachtek to other camera and to computer, and i not have so much noise like with gh2.

    additional info, the 3,5 to 2,5 mm adapter is two section be cause i tested also with three section adapter and not work...
  • nomadnomad
    Sorry, but the whole setup with these tiny connectors is crap for any serious audio. Rather use separate recording and use the internal mike for syncing with PluralEyes.
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