GH4 audio bug discovered

[wwjd]

Can you record something with your Rode Video Mic set to the 0 dB setting ( standard "normal" setting ) and your GH4 set to -12 dB, and then send a link to download this sample. ( either privately or publicly )

I'll give you my opinion on what it sounds like to me, and I'll send you a finished version of the sample using my standard workflow for audio.

You should be able to get quite good sound from the Rode Video Mic, with little hiss. ( assuming that you record in a quiet place )

Challenge accepted! I don't have a quiet studio, so I'll see if my bathroom is dead enough (I live in an apartment subject to neighbors, fans, A/C etc - right now I hear the humm of my fridge, and I think someones A/C fan motor)
I DO think the noise floor is totally good and low enough to be useful, I'm not saying that... I was saying I CAN hear hiss as opposed to not hearing hiss at all. My H2 has hiss at the noise floor (everything does), and it might be a little better - I should dig it out and do a side by side.
I can always gate, expand, or EQ to fix... and I LOVE the RODEs - have the stereo one too, but it adds more noise than mono.

I'll post up a link later

 

[TheDingo]

One thing though. I still think panasonic should address/fix the buzzing while monitoring the audio whether it's being recorded to the file or not. It is still a huge issue for people who monitor from the camera jack and it's unacceptable to just leave it without any fix.

I totally agree, but you might end up with a firmware fix where they lower the amount of headphone volume or reduce the amount of pre-amp gain back to GH3 levels, neither of these would be a good solution to me.

Having to send in your GH4 to be modified would be a better solution, but this might mean no camera for quite a while.

A direct replacement would be best of all, but I doubt that Panasonic would ever go that route.

 

[Ed Kishel]

Can you post a quick video test file straight from the camera ( GH4 audio level set to -12 dB ) with no processing? I would like to investigate the audio your camera is recording.

Too much testing yesterday- batteries dead. Once it's charged I'll give it a try.

 

[Fran Guidry]

So you're saying that a fluttering that changes as the shutter speed changes is normal?

He's saying that if you add enough gain to _any_ source you'll hear noise. Since the audio circuitry in the camera is in close physical proximity to the imaging electronics the self-noise in the audio can be expected to vary with different imaging settings.

As I said, the audio has been normalized.

If you were using a Sound Devices 7xx, recorded no input, and normalized the result you'd hear noise. Normalization raises the highest peak to the specified level or 0 dB if no level is specified. So whatever is in the file is cranked up to 0 dB and becomes audible.

In order to evaluate the noise performance of any recording chain it must be calibrated to normal usage levels. No recording chain ever created is without noise, a simple passive resistor generates noise. A short piece of wire generates noise. If you raise the gain enough (for instance, by normalizing) you can hear the noise of a short piece of wire.

Fran

 

[wwjd]

Can you record something with your Rode Video Mic set to the 0 dB setting ( standard "normal" setting ) and your GH4 set to -12 dB, and then send a link to download this sample. ( either privately or publicly )

I'll give you my opinion on what it sounds like to me, and I'll send you a finished version of the sample using my standard workflow for audio.

You should be able to get quite good sound from the Rode Video Mic, with little hiss. ( assuming that you record in a quiet place )

k, so here's what I recorded:

https://copy.com/qeUnfptsqWPi

unplugged the fridge, and used the closet furthest from chirping birds outside.

recorded (no limiter, no wind cut):

- rode mic -0
- rode mic -12
- built in mics -0
- built in mics -12
- a limiter test that is way louder than the previous tracks, be warned (background sound is my noisey CPU in this clip)

dropped files into REAPER DAW as is, and trimmed shorter removing button pressing audio, no processing or changes in audio, and dumped out as WAV

I CAN HEAR the tiniest digital sizzle on the rode tracks, but it is buried at -56 or so down with the hiss and makes no difference to me.
this stuff is totally usable. If I'm looking for clean 90db dynamic range, I'm using the wrong tool. (GH4)

PS I was impressed with the built in limiter working well shouting into the mic at 1 foot.

Also, I notice some "pumping" after my whispers. kinda interesting. like maybe a built in noise gate of some kind is in the circuit.

 

[Sol M.]

He's saying that if you add enough gain to _any_ source you'll hear noise. Since the audio circuitry in the camera is in close physical proximity to the imaging electronics the self-noise in the audio can be expected to vary with different imaging settings.



If you were using a Sound Devices 7xx, recorded no input, and normalized the result you'd hear noise. Normalization raises the highest peak to the specified level or 0 dB if no level is specified. So whatever is in the file is cranked up to 0 dB and becomes audible.

In order to evaluate the noise performance of any recording chain it must be calibrated to normal usage levels. No recording chain ever created is without noise, a simple passive resistor generates noise. A short piece of wire generates noise. If you raise the gain enough (for instance, by normalizing) you can hear the noise of a short piece of wire.

Fran

Thanks for the feedback. I'm aware of what normalization does (I didn't just hit the "enhance" button ). The point of the test was to provide an example of what users are hearing. I consider "noise" to be white noise or hiss, not "helicopter noise". However, if you're saying that the helicopter noise is to be expected (though it wasn't present on the GH1, GH2, GH3, or any other camera I've used in the past for that matter), then I guess I'mglad (?) that my camera isn't defective.

In any case, the helicopter sound peaks at -58dB (with a minimum of -59dB) with GH4 mic level set to -12dB.

 

[kentfry]

GH3 Audio Settings

GH3 Audio Settings

Hi Philip,

How do you change the GH3 Audio settings - the AGC just ups the tone one my GH3 so that it always shows at -7db? Changing the Mic Level Adjustment on the GH3 has no effect. Tone comes from an SD MixPre-D, from the tape out to the GH3 Mic in. Tone is at 0db on the SD MixPre_D, cant be altered.

 

[Ed Kishel]

OK- take your pick...

The following PRIVATE folder contains the videos below. Straight from the camera. Throughout all runs- camera set to Manual Movie mode, shutter at 1/50. AVCHD, 1080 24p 24mbs NTSC. Audio limiter turned off. Headphone output (when used, set to 10 mid position). Feel free to download and insert into your editor. The .mts files correspond to the test descriptions below. The video is dark as I turned off the lights to minimize any AC noise. Each video runs for approx 6-15 seconds.

There is allot of stuff here, so it may be a little overkill- but I was curious if it made any difference if there was headphones attached or not. I wanted to be safe and do as many variations as I had time to. In particular, runs 0008 through 0015 were done to kill the on-board mics without adding any additional hardware to the mic input- this has always resulted in simple self-noise from the camera (at least in all my other cameras with 3.5mm mic inputs).

links to the individual camera files:
https://drive.google.com/folderview?id=0B2D6Lba7QMEWVExXQTNseTJNTzA&usp=sharing

link to everything zipped:
https://drive.google.com/file/d/0B2D6Lba7QMEWQ3VINnJNNHdqRTg/edit?usp=sharing

tests conducted:
0000 on board mic / level set to +6 / no headphones
0001 on board mic / level set to 0 / no headphones
0002 on board mic / level set to -6 / no headphones
0003 on board mic / level set to -12 / no headphones
0004 on board mic / level set to +6 / w/headphones
0005 on board mic / level set to 0 / w/headphones
0006 on board mic / level set to -6 / w/headphones
0007 on board mic / level set to -12 / w/headphones
0008 3.5mm mic in cable attached / not connected to beachtek / no headphones / level set to +6
0009 3.5mm mic in cable attached / not connected to beachtek / no headphones / level set to 0
0010 3.5mm mic in cable attached / not connected to beachtek / no headphones / level set to -6
0011 3.5mm mic in cable attached / not connected to beachtek / no headphones / level set to -12
0012 3.5mm mic in cable attached / not connected to beachtek /w/ headphones / level set to +6
0013 3.5mm mic in cable attached / not connected to beachtek / w/headphones / level set to 0
0014 3.5mm mic in cable attached / not connected to beachtek / w/headphones / level set to -6
0015 3.5mm mic in cable attached / not connected to beachtek / w/headphones / level set to -12
0016 3.5mm mic in cable attached / connected to beachtek (pots @0) / no headphones / level set to +6
0017 3.5mm mic in cable attached / connected to beachtek (pots @0) / no headphones / level set to 0
0018 3.5mm mic in cable attached / connected to beachtek (pots @0) / no headphones / level set to -6
0019 3.5mm mic in cable attached / connected to beachtek (pots @0) / no headphones / level set to -12
0020 3.5mm mic in cable attached / connected to beachtek (pots @0) / w/headphones / level set to +6
0021 3.5mm mic in cable attached / connected to beachtek (pots @0) / w/headphones / level set to 0
0022 3.5mm mic in cable attached / connected to beachtek (pots @0) / w/headphones / level set to -6
0023 3.5mm mic in cable attached / connected to beachtek (pots @0) / w/headphones / level set to -12
0024 3.5mm mic in cable attached / connected to beachtek (pots @0) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to +6
0025 3.5mm mic in cable attached / connected to beachtek (pots @0) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to 0
0026 3.5mm mic in cable attached / connected to beachtek (pots @0) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to -6
0027 3.5mm mic in cable attached / connected to beachtek (pots @0) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to -12
0028 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to +6
0029 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to 0
0030 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to -6
0031 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) / w/headphones / level set to -12
0032 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) /no headphones / level set to +6
0033 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) /no headphones / level set to 0
0034 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) /no headphones / level set to -6
0035 3.5mm mic in cable attached / connected to beachtek (pots @10) with Rode NTG2 mic attached (AA powered) / no headphones / level set to -12
0036 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / no headphones / level set to +6
0037 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / no headphones / level set to 0
0038 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / no headphones / level set to -6
0039 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / no headphones / level set to -12
0040 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / w/ headphones / level set to +6
0041 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / w/ headphones / level set to 0
0042 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / w/ headphones / level set to -6
0043 Connected to Shure m367 (no mics & pots @0) / 0dB 1kHz tone (on then off) / w/ headphones / level set to -12

...if I missed anything let me know. If these files sound similar to those who aren't having an issue, then I'll make like a clam about my GH4 audio. If not- well...

This whole I hear it, I don't doesn't really matter. Panasonic was able to repeat the issue themselves. If it wasn't a problem, they would have come back with "this is normal for the GH4". They came back and said- (I paraphrase) "OK we hear it, so use our mics and if you want to use your own, then go through our YAGH adapter". I don't particularly care for that answer.

So for those who don't have or hear this buzz on theirs, well you lucked out. But Panasonic heard something. I will give kudos to them for jumping on it quickly, and (as a business owner myself) for using it as an opportunity to sell more gear . Sarcasm aside- thanks again to Panasonic for reacting so quickly to the FB thread. And this is still one bad-a** camera.

If I knew panasonic wasn't going to change any future hardware- well I could work with it. But I'd be pissed if they tweaked something in new production runs so soon. This noise is subtle and for many users it's a non-issue, I'll give it that- so I'm really on the fence about returning it while I can and seeing what Panasonic does. Yes I'm an early adopter, and sometimes early adopters get the immense joy of trouble shooting the growing pains of a new product. But I have 9 days to decide if I adopted too early.

 

[wwjd]

ed, I tried file 0023 to compare against my audio.... I definitely do NOT have that 60hz hum you got there. But, all my recordings were at the 24hz mode.

NOW, here's where it gets interesting: out of curiosity, I went ahead and switched up to 59.9999hz mode, and heard the sound you got in my headset.... the camera told me to restart with the new mode, and after power off and back on, the sound was no longer there. I switched back to 24hz and that was still fine. Tried switching up a bit later but didn't hear it... or my computer and fridge were too much louder.

 

[Ed Jeffersen]

This makes me sad. I have the noise problem. It is not a "hum" or a "buzz and has nothing to do with "ground". The interference seems to be emitted by the CPU and introduced via induction. Remember the old telephone suction cup transducers used for recording conversations? That is an example of audio picked up by induction. Others have noted the pitch or frequency changing when adjusting the shutter speed. I also hear a similar electronic interference when focussing. The problem DOES exist on the files. I do not think this can be fixed by firmware. (I sincerely hope I'm wrong about that) This is a hardware problem. A design flaw.


I can work around the issue by setting the camera level to -12dB and adjusting my MixPre D or Sennheiser receivers to match. The two active Rode mics I own, if boosted to +20dB, are a bit too hot and clip the camera input unless the limiter is enabled. Unfortunately the gain pumping is very audible in that situation. If I set the Rode mics to 0dB, and boost the camera level, the noise becomes unacceptable. I might try a small snap-on ferrite bead around the mic cable.


My GH3 does not have this problem. I'm quite happy to shoot my talking head projects with my AF100, but was hoping to lighten my load and improve the image (which has been accomplished) with the GH4.


I want to know what Panasonic is going to do about this before my return period expires.

 

[Ed Jeffersen]

Further testing today. In M stills mode the noise is a distinct "beep" that changes with shutter speed adjustments. Focus motor noise is also heard.
in movie mode the noise is a steady fluttering sound that seems to match the frame rate. Could it be related to time code?

 

[Harry Pallenberg]

Anyone notice a louder / deeper / lower sound when WIND CUT is on vs. off?

 

[Ed Kishel]

ed, I tried file 0023 to compare against my audio.... I definitely do NOT have that 60hz hum you got there. But, all my recordings were at the 24hz mode.

NOW, here's where it gets interesting: out of curiosity, I went ahead and switched up to 59.9999hz mode, and heard the sound you got in my headset.... the camera told me to restart with the new mode, and after power off and back on, the sound was no longer there. I switched back to 24hz and that was still fine. Tried switching up a bit later but didn't hear it... or my computer and fridge were too much louder.

I tried that, but I hear it in both- 24hz and 59.9.

 

[TheDingo]

k, so here's what I recorded:

Thanks. I will try and get to this in the next day or so.

If I'm looking for clean 90db dynamic range, I'm using the wrong tool. (GH4)

I haven't found any DSLR camera that has a better dynamic range than the 63 dB found on the GH3 / GH4 cameras. ( Canons and Nikons are all worse )

Weirdly enough, I have an old Panasonic handy-cam HS700 camera that records audio clean down to -82 dB with AC-3 compression. Must have been a lucky fluke in Panasonic's design for this camera.

PS I was impressed with the built in limiter working well shouting into the mic at 1 foot.

Yes, the GH3 / GH4 limiter is actually pretty effective. I just wish I could get it without the dang AGC circuit.

Also, I notice some "pumping" after my whispers. kinda interesting. like maybe a built in noise gate of some kind is in the circuit.

It's the freaking AGC circuit that I wish that Panasonic would allow us to turn off all by itself, as it's the most useless feature I've found in consumer audio. AGC is always bad.

 

[TheDingo]

How do you change the GH3 Audio settings - the AGC just ups the tone one my GH3 so that it always shows at -7db? Changing the Mic Level Adjustment on the GH3 has no effect. Tone comes from an SD MixPre-D, from the tape out to the GH3 Mic in. Tone is at 0db on the SD MixPre_D, cant be altered.

When I record the 1 kHz test-tone from my SD MixPre-D using either LINE level output with a 20 dB pad or TAPE level output with a 10 dB pad, and the GH3 audio set to 1, the AGC circuit appears to only have a 3 dB effect on the audio I record. So I can pretty much eliminate the effect of the AGC circuit when I record this way. Setting the camera audio level to a higher setting, or feeding my GH3 a weaker signal will bring back the dreaded AGC monster.

 

[TheDingo]

OK- take your pick...

Wow! Triple helpings!

...It will definitely take me a couple of days to go through this, but I will give you my 2 cents when I get a chance. Thanks!

 

[Chadfish]

Thanks. I will try and get to this in the next day or so.

Yes, the GH3 / GH4 limiter is actually pretty effective. I just wish I could get it without the dang AGC circuit.

Just turn off the limiter. You can totally turn that off on the GH4. There isn't the thing like on the Gh3 where you have different levels of limiting you set. You just have it off or on.

 

[Chadfish]

Here's a video I made using the Rode VideoMic Pro going straight into the GH4. VMP set to 0db, GH4 set to 0db. Limiter on. It seems to be a fairly nice all around setting. We had a loud guitar amp going, and it didn't clip or distort the input, yet it picked up voices nicely. No noise in the recording, and I wasn't wearing headphones.

 

[Erik Naso]

After reading and hearing the issue I tested my setup again and I dont have the issue. The only mic I have with a 3.5mm plug and it's a brand new Rode Lavalier with interchangeable ends. I cranked up the level to +6db with headphones on and I didn't hear anything like what is being posted other than noise from the preamp ready to blow. Did the same with my Sennheiser EK 2000 and nothing except now my ears hurt! Man it's loud! Ha! I accidentally covered the lav with my hand and holy smokes the feedback blew me backwards. LOL!
So I'm at a loss. I think it must have something to do with the type of mic used and the adapter if it's not a native 3.5mm plug. Sorry for not being any help and I sure hope the issue can be fixed for the applications that are causing this.

I had my camera set to shutter angle not shutter speed. Maybe give that a try.

 

[Ed Kishel]

Some people don't have or hear the issue, some do, and for some who have it it's louder than others- so this may not be any issue that every GH4 exhibits. So many different microphones and headphones, different settings, and different shooting situations out there. We just need more people who don't have the issue to record samples at +6dB with a turned off mic attached (regardless of whether or not they shoot that way). Lots of people out there saying there is no buzzing, but not many of them post examples with the camera configured in a way that facilitates hearing it. Lots of examples like Chadfishes (yes- which sound great) but these are all examples during actual shoots. We need more examples from non affected cameras during silent recordings- and at all 4 gain levels.

Here is an example of someone who also says they don't have the issue- but you can hear it. Use headphones. There aren't many silent pauses during this example, but you can hear it at 27seconds (when the boy says "it"). It's faint, and you have to listen for it. I will admit this is definitely "audio peeping"- so if you weren't looking for it you probably wouldn't hear it. And this is why for many following this thread- this is much-ado about nothing.
http://vimeo.com/91353864

Erik, can you hook up a microphone with a 3.5mm TRS connector (like your Rhodes) to the camera but make sure the mics turned to the off position. Connect headphones. Turn up your gain to +6 and record a short clip in 1080 24p AVCHD 1/50 shutter with the limiter turned off. And please post the .mts file if possible. Raw is best, but vimeo is OK.