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OT- Video editing guru's.... filtering background noise ?

Milacron

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Interview at my shop where the air conditioning fan is way louder in video that it seemed in real life. iMovie has background sound filter, but the more you eliminate the undesirable fan noise the more the speech is effected as well. Equalizer "voice enhance" makes speach sound worse if anything. Just wondering if more sophisticated video software might work better for this purpose ? And if so what exactly...
 
I don't do much video editing but when I do I use my audio recording software - Reaper. It has fairly sophisticated filters that you can use to "learn" and then subtract background noise.

My recording PC is in the same room where I track (home studio) so the fan noise is always an issue.

If'n you'd like I can take a crack at it but there needs to be enough of a break in other noise that I can build the profile. Usually a good ten seconds or so of just background noise is more than enough.
 
What you need for such things is a noise cancelling microphone that will plug into the iPhone. Typically, a headset with boom mic in front of the mouth is used.

There are many cheap headsets that claim to have noise cancelling mics, but their cancellation is not all that effective. One needs to go up the price scale a bit.

Noise cancelling mics are also good for cancelling your own echo in a hard-walled room, like many shops.

Noise-cancelling is really a marketing term. What is actually going on is that the mic can distinguish between distant sources of sound and close sources, and rejects the distant sources. This is accomplished acoustically in the microphone assembly.
 
Spent many years as a location audio engineer. Turn the fan off (next time). This time, Rick's Reaper module or similar. Beware sync if processing audio separately from video. If you have cutaways to B-roll of machines, etc. you can make adjustments easily.

Higher-end video edit programs have various plug-ins for audio and video that are pretty magic. Not sure what iMovie has to offer in this realm.
 
I also worked as an engineer at professional studio as well as TV stations. I never saw any good way to filter out the noise after it was recorded. We went to great extremes to eliminate the noise while recording. One very effective method is to simply turn the AC off while recording. Beyond that, it gets complicated, difficult, iffy, and down right expensive.

If the AC is a central unit with ducts, you can try using duct with insulation on the INSIDE AND putting at least three 90 degree bends in it between the shop and the fan. Be sure to super size the duct work (about 4X the cross sectional area - no joke, four times or greater). And increase the size of the grills or use ones that are quiet. But if the unit is located in the shop this will probably not work as the noise will be coming straight from the unit and not through the duct. When professional studios are built, the location of the AC and the configuration of the ducts are of prime importance.

Sorry about that, but it is the cold, hard truth.



Spent many years as a location audio engineer. Turn the fan off (next time). This time, Rick's Reaper module or similar. Beware sync if processing audio separately from video. If you have cutaways to B-roll of machines, etc. you can make adjustments easily.

Higher-end video edit programs have various plug-ins for audio and video that are pretty magic. Not sure what iMovie has to offer in this realm.
 
If you've got some time to kill, you can venture into the world of 'ADR' -- Automatic Dialog Replacement. Not so automatic here, however. It's re-recording the audio in-sync with the existing video. You can use your existing audio as a guide track, to get lip sync right, etc. It can be vexing to jump into all at once, as it requires significant patience and a good eye for sync. Rehearsing and recording line-by-line makes it easier. Not even sure if iMovie can allow you to record a track in-sync with the video and play it back immediately.

You can do it with iPhone clip playback and a 2-track recording device (so you can listen for audio sync on quick playback.)

Then it's back to edit to put it all back together.

Now you see why I recommend turning off the fan next time... ;)
 
Naw....all video's these days just use extremely loud thrash metal "Moosic".....:nutter:

Crank it UP !
 
I have had success with exporting audio from my video editor and bringing into Audacity to tweak it. Most important thing is not to change timing of anything from the when you export audio till importing fixed audio. That way lips and words line up.

That has worked for me, but I do have a decent amount of experience in Audacity and a lot of experience with live sound and EQ. Your results may vary.
 
I don't do much video editing but when I do I use my audio recording software - Reaper. It has fairly sophisticated filters that you can use to "learn" and then subtract background noise.

My recording PC is in the same room where I track (home studio) so the fan noise is always an issue.

If'n you'd like I can take a crack at it but there needs to be enough of a break in other noise that I can build the profile. Usually a good ten seconds or so of just background noise is more than enough.

I haven't done much video with audio but I do some audio recording and the technique described can work wonders if you have a section of nothing but noise to sample.
 
And re-reading the original post -- You mention it's an interview. If you recorded each mic on a separate channel, you can mute the un-used channel and cut the noise in half immediately. Make sure one channel or the other is on, though -- unless there's a music bed which would hide the 'no background noise at all' situation.

You've probably posted the video already, so I'll quit with the recommendations...
 
Isn't there a way to use the other channel, without the interview audio in it, and difference the two channels, cancelling a lot of the ambient noise?

An aside, for anyone who hasn't seen it before, Coppola's film "The Conversation."
 
Isn't there a way to use the other channel, without the interview audio in it, and difference the two channels, cancelling a lot of the ambient noise?
Problem one being that A/C is almost a white noise source.
Problem two is phasing since mic one and mic two not in line to the noise source so different timing on the wave fronts.
A 5k wave is only 3 inches long.
Bob
 
Whatever music they use is always ten times louder than the speech. So you start a video with some questionable music and turn the volume way down. Then you can't understand a word they say.

Brilliant! Some people never grow up.



Naw....all video's these days just use extremely loud thrash metal "Moosic".....:nutter:

Crank it UP !
 
Wavelength and distance. Bingo!

Noise canceling microphones have two pickup elements or entry ports, one facing the speaker and the other facing the opposite direction. These two are very close to each other but even then there are problems when the higher frequencies are desired. This technology has improved from the WWII aircraft mikes which were limited in their high frequency response, but still leaves something to be desired. Using a second microphone, even one that is literally an inch or two away from the first one, will only accentuate those problems. Frankly, in 45+ years of professional experience, I have never seen noise canceling, with either one or two microphones, actually used.

You can try a noise canceling microphone if you want. But the problem is most digital video cameras and phone cameras do not have a microphone input so you have to record that microphone on a separate device. Or get a high end camera with a microphone input.

In open space, sound intensity decreases with the square of the distance from the source. This is why you often see microphones placed only inches from the speaker's lips. The closer the microphone is to the speaker, the more intense (louder) the speech is in comparison to the background noise which is coming from a much greater distance. A directional microphone can also help. Of course, you must point it at the speaker's lips, not off to the side. Again, most microphones that you see being used by the pros are directional. Boom microphones, which are on a pole above the talent but out of the shot, are often highly directional. They are usually held or operated by a boom man who must keep them pointed at the speaker's lips at all times because even a small error in their orientation would result in a large fallout in the level of it's output.



Problem one being that A/C is almost a white noise source.
Problem two is phasing since mic one and mic two not in line to the noise source so different timing on the wave fronts.
A 5k wave is only 3 inches long.
Bob
 
Filtering noise after it is recorded is the least effective, highest effort method to improve audio quality.

The better method is:
1) Move the microphone closer to the desired audio source.
2) Reduce the unwanted sound source level (turn off the fan or A/C)

There are some amazing machine learning algorithms but I don't think they are commercially available yet and will likely be expensive when they are commercialized.
 
Hem's sake. Shed the audio entirely. Studios have more mics and more "channels than a civilian would believe, still add more content, later, after "mining" the live catch.

It is not live-streamed in "real time".

KISS for smaller budget is to record a voice-over / machine-tool over.
Before OR after.

The motion vid - edited very simply - becomes but the background filler to the well-crafted MESSAGE.

Once hired John Cleese to do a Cable & Wireless Commercial. Nothing to do with what he was "famous" for. Only that he WAS a widely recognizable figure and could capture the viewer's attention, then "present" very well. As he did.

You see it all the time with famous figures peddling inch-hoorance, reverse mortgages, vitamin pills, and .. would yah believe. their election to political orifice?

Works well-enough.

Cue "Guns of Navarone", "Life & Times of Judge Roy Bean", or 'Zulu" for voice-over intro or other examples done very effectively as attention "grabbers".

Example:

YouTube
 
Isn't there a way to use the other channel, without the interview audio in it, and difference the two channels, cancelling a lot of the ambient noise?

An aside, for anyone who hasn't seen it before, Coppola's film "The Conversation."

Not really applicable to the OP's issue, but there are audio tools used in film post work that let you (graphically, I believe) phase-align boom and lav production tracks, dynamically, to be able to use both simultaneously if you want -- without phasing issues. That's before any DSP fixes for ambient noise, etc...
 








 
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