I give up. . .how do I eliminate hiss in post? at DVinfo.net

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Old May 22nd, 2003, 03:17 AM   #1
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I give up. . .how do I eliminate hiss in post?

Using my ME66 as a boom mic, there's often very low level noise picked up while recording dialogue. If I edit a scene where I have to raise some people's levels, then that hiss/noise gets raised with it. How do I eliminate that noise, so that when I raise levels, there's no hiss?

This guy who specializes in audio told me to use a notch filter. I assume that means taking an EQ (using Vegas 4, for me) and going through each frequency, and lowering it all the way down, until you find the frequency that the hiss/noise is on. Well, I tried that, but so far it's only worked once. Every other time, I spend forever moving the "notch" around, only to find there's hiss in every band!

Isn't there another way?

By the way, I still don't have a windscreen. Is this my problem? I'm not talking about wind noise. . .just basic noise at a very low level that only shows up when the volume is raised. Still though. . .
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Old May 22nd, 2003, 04:41 AM   #2
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That is so weird, i don't hear about hiss so much with a xl1s.

Hiss is a funny thing, it is kinda like white/pink noise, it just invades a lot of frequencies.

How to get around this without re-recording all the audio again is next to impossible, but to rule some stuff out, what are you monitoring your audio with?

Are you sure it is not caused by the amplification or audio setup of your computer?

Or the sound card, before you come to the conclusion it is the xl1s?

Zac
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Old May 22nd, 2003, 06:48 AM   #3
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I have used Sound Forge to "tweak" audio, and have had some success in removing odd noises like hiss. So, I will assume that Vegas, being made by the same people, will have the same filter. I haven't used Vegas in a while, but I know that even Premiere has a hum and notch. If not, you will have to go through it one frequency at a time. I forget what frequency hiss will normally reside in. When you find it, save those settings as a preset.
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Old May 22nd, 2003, 07:00 AM   #4
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Sonic foundry have a Plug in called Noise reduction, steinberg also have a plug in of a similar vein...

I use noise reduction when im restoring old tapes as wella s removing unwanted environmental hums and hisses...

one thing is that your problem may not stem from the mic, it could be a weak line leading to the cam, or even the cams recording heads as well...

Noise reduction is the best way to refine the sound IMO...
Notch filters are ok, as do paragraphic eq's and noise gates (to a point) but which noise reduction, you can capture a second of the noise your wishing to eliminate and it will configure itself to remove those freq fluctuations.
also when EQing, it might be an idea to cut the high shelf.. running a cut off freq filter plugin might also help, but dropping gain usually wrks.

good luck
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Old May 22nd, 2003, 11:56 AM   #5
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I tried using a shelf. I had to extend it from 20k all the way to around 300hz or so to get any good result! Isn't that noise reduction filter ridiculously expensive?


You're saying that ideally, I should be able to capture with my mic and not get any noise at all in the background, no matter how much I raise my volume?
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Old May 22nd, 2003, 12:03 PM   #6
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Yes, the Noise Reduction filter from Sonic Foundry is great, but expensive. Sometimes you can get it bundled with Sound Forge for just slightly more than its original cost. Usually you are look at more than $200.
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Old May 22nd, 2003, 12:09 PM   #7
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It could be the computer I guess. . no way to tell.
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Old May 22nd, 2003, 12:30 PM   #8
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i actually think it might be your camera, i dont knwo what your using though, so who knows...

One thing to note is that if your using standard PC monitors the sound wil be different, obviously due to the quality and EQ settings etc etc...

if you use a good quality set, this shoudl help eliminate nuances in what your actaulyl hear and give you a more acurate rendition.

as for recording, it could also be that your gain is set too high...

I usually run a lil lower than needed, then normalise the sound during post.
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Old May 22nd, 2003, 02:05 PM   #9
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I should record low? The thing is, the show that most of this stuff with the noise/hiss is for is on Public Access, and the equipment there totally sucks or something, because I have to have my peaks at -6db, instead of -12.
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Old May 22nd, 2003, 08:03 PM   #10
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Hiss in post -- isn't that what they tie horses to? :-)

Not much can be done if the hiss is like "pink" noise, in which case it's spread all over the spectrum. An EQ filter can't take it out at all.

Attempting to bring levels way up in digital post might be a problem since there might be artifacts that add to the noise. Try acquiring through an analog route, using a mixer to bring up the gain to normal levels. Might be worth a try.

Good luck!
Dean Sensui
Base Two Productions
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Old May 22nd, 2003, 11:34 PM   #11
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I don't own any of that stuff, mixer and all. I need a solution that doesn't cost 200 dollars, and can be found in Vegas, Sound Forge, or something cheap. "Get good audio during acquisition," you say, well I can't. I have no way of monitoring audio while also checking my viewfinder.
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Old May 23rd, 2003, 02:17 AM   #12
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if ur using soundforge, (even in vegas actaully) u can run a paragraphic EQ preset for hiss removal

this might help...

the problem here could stem from many factors...
the solutions may be many and varied...
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Old May 23rd, 2003, 04:14 AM   #13
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What about track compression? Wouldn't this lower the difference between the louder and softer parts? I don't know much about compression, except what it does. Can anyone recommend a ratio (2:1, 3:1 etc.) and the threshold settings, as well as whatever else you might find relevant?
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Old May 23rd, 2003, 09:55 AM   #14
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compression is used to confine teh freq distribution range of certain frequencies..

for speech a ratio of 2:1 is usually tight enough... basically what your doing with compresion is "tightening " up the freq fluctuations of the signal.. for basses a higher compression with a short envelope are usually good if you want to acentuate teh lower end roll off..
for speech its always an idea to chain a slight reverb after the compression to give it a fuller steadier sound.
You could also add vocal harmonisers or harmonic exciters for that added sparkle, but for video it might be a lil overboard.

compression it wont do much for noise reduction thou...

at least an uncompressed white noise can have some processing done to it.. if its compressed, itll make it harder to rectify later on as the freq are bought closer together, and it'll end up being a lot more work to segregate them again if you wnat to do so in teh future.
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Old May 23rd, 2003, 12:45 PM   #15
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Yeah, but, what I was saying was that by compressing, don't you lower the difference between the low parts and the high parts? Don't push down the high parts and push up the low parts so that there's less between them?
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