the best way to reduce noise? [Archive] - DVXuser.com -- The online community for filmmaking

etrust

11-05-2009, 07:24 AM

Alex H.

11-05-2009, 07:52 AM

Cam: HDR-XR500

Im refering to microphone noise

Tha Rode mic is connected on my cam (mini jack)

And there's your problem. You are connected to a consumer camcorder with 1/8" in. So you're dealing with the camera's less-than-adequate pre-amps.

At this point, the best way to improve your results would be to invest in an XLR converter box with phantom power... look at JuicedLink or Beachtek. This will allow you to take an XLR connection in, and will adapt it down to the 1/8" in for your camera. It doesn't completely bypass the camera's pre-amps, but it sends a strong enough signal that they don't work as hard and introduce less noise.

Even a converter without phantom, using the NTG-2 with a battery, will give a significant improvement.

Chamber005

11-05-2009, 08:26 AM

Hi,

ok here some details:

Cam: HDR-XR500

Im refering to microphone noise

Tha Rode mic is connected on my cam (mini jack)

I can hear the noise in After Effects or Vegas or on recording the footage on the headphone :=(

The Rode Mic NTG-2 seems to be good and a lot of people told me to buy it, but there is to much noise :=(

What im doing wrong? On my cam i have only the possibility to choose 5.1 or stereo mode and that's it.

please help me to get a decent result with this mic.

thank you

I just finished using wired countrman B3s, XLRs inputs and a solid preamp for a shoot and I have noise in the raw sound file. You need to run your sound through a clean up program. I'm using Adobe Soundbooth in conjunction with Premiere Pro CS4 and everything is coming along pretty good.

I think to get great sound within the actual original recording you need to be using high end equipment (which neither myself nor you really have). The best thing we can do is just sweep the dust under the rug and hope for the best.

But no one nowhere can fix the audio if your redline your decibles, but I don't think that's your problem.

Just remember that you need to do everything to sound that you would do to your image (e.g. color balancing, correction, even potentially some framing). The sound needs just as much care and attention (sometimes even more). Most clean up programs will allow you to choose the sound you DON'T want. So, usually, you can just select the "noise" when no one is speaking or moving (one of those times you recorded the ambient sound, which hopefully you did), and then you can just tell the program to find that noise and get rid of it across the board.

Soundbooth has a pretty sweet generic clean-up, though.

Good luck!! This is my first real go at sound on my webseries after getting lots of help from the guys here, so we'll see what the final product is like once I'm done editing the 3rd ep, but so far the above advice is working for me.

Noiz2

11-05-2009, 11:05 AM

As Chamber005 said you have limits. Ine thing that will help is to get some sort of adapter. If indeed the mini is a mic in then it is probably providing power that you don't want. Also it will be expecting the TRS to be stereo not the different legs of a balanced mic. The other problem you probably have is you probably can't turn off the Auto Gain Control. Recording sound with the AGC on is like shooting with auto focus on, you get some very distracting moves that you have no control over. There are boxes out there that can help with all of that but if your serious about stepping up the sound then you probably need to either up the camera or go dual system. A small recorder than has XLR ins will cost a lot less than a new camera so...

Assuming no $ to throw at the problem. Turn off AGC if it's possible to do so. Get an adapter that can block the camera power (probably any "box" that goes from XLR to mini will do that, a straight cable with matching connectors will not).

Noise reduction in post is tricky. There are a lot of tools some very affordable some very good a few that are pretty good and affordable. Even the cheapest if used VERY carefully can help a lot with hiss. The catch is you need to use them with a good playback system that is calibrated (for just cleanup you "might" be able to use headphones, maybe. Using cheap speakers will mask the problems that NR will add to your sound so, as I said, it's tricky. The less you need to use (NR) the better the more affordable tools will work. There is a reason that the top NR box goes for around $30K and people are willing to pay that.
If you can't turn off the AGC then you will probably need to cut out all the "dead air" you can from your tracks and replace it with some room tone, because the AGC will pump up the noise every time it gets quiet.

Richard Crowley

11-05-2009, 11:35 AM

And there's your problem. You are connected to a consumer camcorder with 1/8" in. So you're dealing with the camera's less-than-adequate pre-amps.

Whoa, hold on there. We don't have a fraction of the evidence necessary to come to that sort of conclusion. Plugging a mic like that into that kind of camera has a very good potential of making quite nice audio recordings.

I would NOT consider the "camera's less-than-adequate pre-amps" to be even in the top three potential suspects in this mystery. We have NO IDEA of what "etrust" even means by "noise". Since he/she apparently doesn't have enough experience to adequately describe the "noise", I suggest that posting a sample online somewhere where we can hear it would be extraordinarily helpful.

Also absolutely required is a far more detailed description of how the equipment is being used. In particular, how loud is the source, what is the ambient noise like, how far away is the microphone, etc. etc. It seems far more likely that we are expecting the microphone to work magic to pull pristine sound out of a low-level source in a noisy environment from too far away. Until we can eliminate ALL of those potential problems, the camcorder mic preamps aren't even implicated yet.

Note further that trying to reduce noise after the fact (in post-production editing) is FAR more difficult, expensive and time-consuming than recording the sound properly at the beginning.

This is NOT the kind of question that can be properly responded to with almost NO information. Anyone who tries to analyze this problem with the evidence so far is just shooting in the dark.

Ted Spencer

11-05-2009, 12:09 PM

^ agreed

Alex H.

11-05-2009, 12:23 PM

Whoa, hold on there...

This is NOT the kind of question that can be properly responded to with almost NO information. Anyone who tries to analyze this problem with the evidence so far is just shooting in the dark.

Okay, disagree with me. But why does it seem so difficult for some folks on these forums to offer a differing opinion without belittling some one else?

Chamber005

11-05-2009, 12:57 PM

Whoa, hold on there. We don't have a fraction of the evidence necessary to come to that sort of conclusion. Plugging a mic like that into that kind of camera has a very good potential of making quite nice audio recordings.

I would NOT consider the "camera's less-than-adequate pre-amps" to be even in the top three potential suspects in this mystery. We have NO IDEA of what "etrust" even means by "noise". Since he/she apparently doesn't have enough experience to adequately describe the "noise", I suggest that posting a sample online somewhere where we can hear it would be extraordinarily helpful.

Also absolutely required is a far more detailed description of how the equipment is being used. In particular, how loud is the source, what is the ambient noise like, how far away is the microphone, etc. etc. It seems far more likely that we are expecting the microphone to work magic to pull pristine sound out of a low-level source in a noisy environment from too far away. Until we can eliminate ALL of those potential problems, the camcorder mic preamps aren't even implicated yet.

Note further that trying to reduce noise after the fact (in post-production editing) is FAR more difficult, expensive and time-consuming than recording the sound properly at the beginning.

This is NOT the kind of question that can be properly responded to with almost NO information. Anyone who tries to analyze this problem with the evidence so far is just shooting in the dark.

I think noise is only going to mean one thing, honestly. There's something there that he doesn't want. It's either popping, scratching or hiss. Whatever it is, it's obviously ambient. And he's already shot what he was going to shoot (as at this stage he's trying to remove the "noise").

I'm unclear why you're saying reducing hiss in post is that big of a challenge, though. I'm doing it for the first time now and it's pretty simple IMO. Any decent audio program is going to have a generic noise removal generator that will work pretty well. If he needs to get more specific he can attack the wave file directly and remove anything unwanted.

unclebob6958

11-05-2009, 01:33 PM

Richard Crowley

11-05-2009, 08:27 PM

Keep in mind, Mr. Crowley, that you are a relative newb here despite your credentials. We get the same questions over and over again so the stock answers apply 95% of the time. Give it a few months and you will find yourself doing the same as you catch on to the pattern. The HDR-XR500 is a consumer product with an 1/8" mini-pin external audio input connector. 999 times out of 1,000 it's going to be the noise problem.

Yes, I may be a newbie here, but I've probably got most of you beat with participation in other forums, particularly Usenet newsgroups, audio, video, cine, and electronics. Yes, I have also seen this question dozens/scores of times before. And very frequently we fly into some pet cause/solution without really knowing exactly what all the presenting symptoms are. Poor medicine however you slice it.

I probably have also been doing audio (long before getting into video) at least as long as anybody here. Since the early 1960s. But I came here first to learn things from the rest of you, and secondarily, to offer whatever helpful response I may be able to add. The Usenet newsgroups, at least the video ones, are dying, and these web-based forums are superseding them.

I apologize to C2V for coming off as a personal attack. I did not mean to do that and I am sorry for it. Please forgive me.

Richard Crowley

11-05-2009, 08:37 PM

I think noise is only going to mean one thing, honestly. There's something there that he doesn't want. It's either popping, scratching or hiss. Whatever it is, it's obviously ambient. And he's already shot what he was going to shoot (as at this stage he's trying to remove the "noise").

"Noise" has an extraordinarily wide definition by the standards of people new to the audio field. But poor signal to noise ratio is primarily caused by inadequate signal level. Whether from poor performances by the actors, or noisy locations, or poor mic techniques, etc. If these are taken care of, even this camera has plenty of SNR that post-production de-hissing should never be necessary.

I'm unclear why you're saying reducing hiss in post is that big of a challenge, though. I'm doing it for the first time now and it's pretty simple IMO. Any decent audio program is going to have a generic noise removal generator that will work pretty well. If he needs to get more specific he can attack the wave file directly and remove anything unwanted.

Removable of wide band noise (i.e. "hiss") without damage to the desired signal is the holy grail of audio. Companies with huge budgets and laboratories full of brilliant scientists, engineers and computer programmers continue to seek this ideal result. Very high-end software/hardware like CEDAR approach the desired effect, but at a huge cost. At least at the present state of the art.

David W. Richardson

11-05-2009, 11:02 PM

Gotta agree with Richard here. When I read the original post, my first thought was: "Was the air conditioning turned off? What about the refrigerator? Water fountain?"

In other words, is the 'noise' environmental? That would be the first thing to look at, in my opinion.

If environmental issues are ruled out, then my next question would be levels. Were the audio levels set too low? Was any kind of gain or automatic level control used?

Richard is right -- we need more info from the OP in order to narrow down the cause.

David W. Richardson

11-05-2009, 11:06 PM

And he's already shot what he was going to shoot (as at this stage he's trying to remove the "noise").

That's not the way I read it. It doesn't sound like he's shot some important piece of video, and now is trying to figure a way to salvage it by getting rid of the noise.

What I get from his posts is that he's trying to figure out why this mic is giving him the noise in the first place -- if, indeed, it is a mic (or some other hardware) problem. It sounds like he's shooting test video and trying to resolve the problem. Maybe I'm wrong.

The sooner the OP tells us more about the problem, or ideally posts an audio clip we can listen to, the sooner we can home in on a solution.

David W. Richardson

11-05-2009, 11:11 PM

One other question.....is there a battery in the NTG-2? And is it fresh? (Okay, that was two questions.)

Ted Spencer

11-06-2009, 06:52 AM

The sooner the OP...posts an audio clip we can listen to, the sooner we can home in on a solution.

This, as Richard Crowley also pointed out, is essential. Otherwise we have no idea what "noise" means in this case.

etrust

11-06-2009, 03:07 PM

Hi all,

thank you very much for all posts.

the rode ntg-2 was conected with a new battery on the jack plugin on the cam. i have only the option on the cam to set 5.1 or stereo. it was stereo.

ok here the test:
http://www.youtube.com/watch?v=xrDmx8RRELE

The original sound is better than this link. I thing it's because i convert to mp4. But the noise problem is the same.

I hope you know what i mean with noise :=)

Please help me to get a nice quality with this mic.

Thank you

Richard Crowley

11-06-2009, 03:46 PM

I hope you know what i mean with noise

Sorry, all I am hearing is the artifacts of compression. Or if that is what you mean by "noise" then it is distortion. If it isn't the artifacts of compression, then my first guess would be that the "plug-in power" from the camcorder is feeding back into the microphone in a way that does not agree with the mic output circuits.

We don't really need to see the video, since that is not the issue.
Can you post somewhere an uncompressed WAV file of the sound?

etrust

11-06-2009, 04:06 PM

hi i know i have some distortion there. But i would like to reduce the basic noise there..

where could i put this uncompressed file?

Chadfish

11-06-2009, 04:24 PM

Upload it to youtube then we can hear what's going on. If you want to fix noise after the fact, there are audio plug-ins that allow you to select a sample of the noise only, then you can pull out the noise from the rest of the clip. It's not perfect, but you can lower the noise. I'm not sure, but Soundtrack Pro may have a filter like that.

EDIT
{{{{{OK I heard your youtube video}}}}}}} Yes you can reduce the noise with a "Noise Reduction" plug-in. I don't know what audio apps you have. Do you have any audio editors?

Chadfish

11-06-2009, 04:46 PM

I don't know if anyone has said this, but firstly a shotgun is not the best choice for indoor use. Second, when recording dialogue the mic should be between 1 and 2 feet from the mouth of the person speaking. This will help get your levels up.

ALSO TURN AGC OFF!!!! Auto gain compensation will raise the noise level when nobody is speaking.

Another thing is to not turn up your audio recording levels up all the way. Try keeping them at 50% - 75% at most. Turning levels up also turns up the noise.

You basically have a consumer camera and a mic plugged straight in. You need to get the signal coming into the camera louder. Maybe a JuicedLink box. YOu must pay attention with box' like Beachtek though because many times they do not turn up the mic, but only attenuate (turn down) from the level of the mic.

You have vegas, which is an awesome audio app. To remove hiss get some noise reduction plugs like I said. Try iZotope RX.Check out this video: http://www.youtube.com/watch?v=wP1PjS7Jrxg&feature=related

THis is cool: http://www.youtube.com/watch?v=HTabBpjweBc&feature=related

stip

11-06-2009, 05:56 PM

I had Izotope RX but switched to Wave Arts Master Restoration, which does a better noise reduction job in my opinion (but is also twice the money)

http://wavearts.com/products/plugins/master-restoration/

David W. Richardson

11-06-2009, 11:04 PM

Okay, I haven't had a chance to check out the clip yet -- the site is blocked here at work. But my next thought would be the connection between the Rode and the camera.

The Rode has an XLR connector, the camera has a stereo mini jack. So are you using a cable with an XLR connector on one end and a stereo mini plug on the other? Are you using one or more adapters to convert the XLR to a mini stereo? Is your mini plug a stereo plug or a mono plug? You could have a bad cable, a bad plug, or a bad adapter of some kind.

On playback, can you tell if the noise is only on one channel, or on both channels? If you're connecting a mono plug into a stereo jack, and the noise is only on one channel, the solution might be (a) a mono-to-stereo plug adapter, or (b) duplicating the good track to the opposite track in post.

Lastly, have you tried the mic on another camcorder? If you can find one with an XLR input, try it on that and see if it still makes noise. If it does, chances are you have a bad mic. If not, more investigation is in order.

David W. Richardson

11-06-2009, 11:23 PM

I've skimmed through the online documentation, and there's not a lot of useful info in the manuals for your camera regarding connecting an external mic. But it does refer to the mic jack as the "MIC (PLUG IN POWER) JACK". Which makes me wonder if it is sending phantom power to the microphone. Maybe try taking the battery out of the NTG-2 and see what happens.

Also, as mentioned before, go into the camera's settings and make sure the mic volume is turned up to an adequate level.

etrust

11-07-2009, 05:21 AM

hi all,

i will be able to do some more tests next week :(

I tested Audacity and i get nice results there.

Why is a Shotgun not the best choise for indoor?

Would you use this rode ntg-2 only for outside? What should i use for indoor and outdoor?

Thank you all for helping me.

Ted Spencer

11-07-2009, 07:42 AM

Shotgun mics achieve extreme side rejection at the expense of back sensitivity, especially at lower frequencies. In an indoor setting there can be considerable reflection off of ceilings, again, particularly at lower frequencies, as well as other noises from above. So you could wind up with quite a bit of LF junk in the sound - boominess from the on-set sound itself, rumble from HVAC and other mechanical devices, thumps from upstairs neighbors walking around, etc.

Outdoors, there's no ceiling for anything to bounce off of, so with the typical downward facing orientation of the mic, its back sensitivity is almost irrelevant aside from things like aircraft. And its side rejection is ideal, because that's where most of the undesired sound will be coming from (traffic, pedestrians, construction crews, etc.).

So indoors, a hypercardiod, which has almost as much side rejection as a shotgun and quite a bit less back sensitivity, is a better bet.

dre83

11-07-2009, 08:47 AM

My first impression is:

- talking straight into the mice (don't, hold it in an angle of 45°)-
- holding mice with your hands..(ok for this example)
- a normal room noise, it's not a big hiss or electric noise
- is the window open ? soundengenieers DO have to suffer from hot weather outside !!!
so always windows closed and NO aircon on,(also a good advice for people recording on the set :-p)

Some solutions

- cut away the very high frequencies (17kHz - 20 kHz) with a EQ (parametric)
- a noise reducer could work also, but take care...

About the shotgun indoor: It's true that the best for indoor is cardiod or hypercardiod (cardiod is good for recording "environment sound of people takling for example".

BUT !! If you only have a shotgun, it's not a shame to use it. Only know that there are better solutions. You can make fire by scratching two stones, or with a lightner...

Chadfish

11-07-2009, 11:45 AM

Try a Rode NT3 for indoor use. Maybe an Ocktiva MK12. Those are the inexpensive choices that still sound great. The NT3 runs on 9v battery too, and with your consumer camera you will need it. It lasts hours and hours on one battery. The NTG-2 has no power switch, and the battery keeps running down until you take it out of the mic.

I'm almost positive the hiss I heard is from the camera. Just turn off AGC, turn down your levels to 50%, and get close to the mic. Try it. Then get an NT3 for indoor use. They sound very very nice.

Noiz2

11-07-2009, 01:18 PM

I'm unclear why you're saying reducing hiss in post is that big of a challenge, though. I'm doing it for the first time now and it's pretty simple IMO. Any decent audio program is going to have a generic noise removal generator that will work pretty well. If he needs to get more specific he can attack the wave file directly and remove anything unwanted.

Don't take this wrong but the above can only be said by someone who has either poor speakers, very low standards or is just not listening all that closely. I suspect the first and last since good speakers and a good listening environment are not all that high on most peoples lists and it takes time and experience to train your ears.

Tape hiss is pretty simple to remove with out having a big effect on the sound (of dialog) but broadband is often VERY hard to remove with out a lot of damage. And if you thing waveform editing is going to get you there talk into a mic and tap it. Now go and remove that thump with out touching the dialog. You won't do it at the waveform level. There are some tools that can do it but now we are talking $.

etrust

11-08-2009, 02:48 AM

Chadfish

11-09-2009, 02:11 PM

Aside from using proper mic technique and gear, here is a tutorial on how to remove noise in Soundtrack Pro from a FCP timeline:

http://www.youtube.com/watch?v=U8uJ9YNZtTY

Also this guy has some awesome free tutorials on Motion. I learned a lot from Emeek77, or "Apple Shake Guru" on his youtube channel.

Steve House

11-09-2009, 03:43 PM

Hi,

i will make tomorrow the last test with the rode-ntg2 without battery and with fresh baterry and will tell you the result.

I have a old Behringer B-1.
http://www.zzounds.com/item--BEHB1

Is this the correct one for indoor?

For indoor what? The B1 is a side-address studio mic. Recording a singer in a studio or an announcer in a voice-over booth, sure. Recording dialog in a dramatic production, no. (Disregarding Behringer's questionable rep for quality mics.)