need to reduce echo in post

droliff

droliff

Active member
Hi all,

I am pretty much a newbie to audio. Here is my situation:
I videotaped a local university dance major in one of the schools large dance studios.
The style of dance is Flamenco so she was using a hard wooden surface to dance on.
I used a Rode NTG shotgun mic pointed at her feet to record the audio. I didn't really know how to reduce the echo inherent in the live environment. What audio filter or combination of filters can I use (FCE v 4) to reduce or dampen the echo in the audio due to the environment in which I shot the footage? Here is a sample clip of the footage:

Margaret Williams/Flamenco

Thanks for any input.

Dennis
 
From everything I have ever read or seen, there are techniques add echo to audio, there is simply nothing to remove echo from audio. That also comes from Barry Green's DVD that I highly recommend you get. I've been using the techniques presented in the DVD and my audio is much better in the recording, makes massive difference in my final projects now.
 
Are you serious? That is funny. There is no remove echo filter in any audio software program. The only way I know of to remove echo is not to record it in the first place. Try rescheduling at a different location.
 
HOLY COW. That is som serious echo. Also it sounds like you are using the on board audio or a mic that is way too far away from the action.
 
thanks for the input. re-read the first sentence in my original post. this is the first time i've run into a pompous reply on this forum.
that's a shame.

Dennis
 
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Unfortunately, reverb - especially reverb that severe - cannot be tamed once it's recorded. Gating and compression can help, a little, but not to a point that you'll have a favorable end-product. Choreography rooms like that are almost like giant bathrooms in that they are the most unpleasing reverb chambers known to man, and there's not a whole lot you can do (short of hanging dozens of sound blankets) to deaden that kind of room.

Listening to the clip, though, it sounds like there was some serious compression/limiting on the signal. I can hear it clamp down on the claps and stomps, and then release with the reverb. That enhances the effect of the reverb as well. What else did you use to record (i.e. into what device was your shotgun mic connected... and which NTG)?

It's also worth noting that a shotgun in a room that reflective is not the best mic choice by far. You could try with a hypercardioid, or even PZM/boundary mics. You'll still record tons of the room's reflections, but they won't compound nearly as badly as with a shotgun.
 
droliff said:
thanks for the input. re-read the first sentence in my original post. this is the first time i've run into a pompous reply on this forum.
that's a shame.

Dennis
Click to expand...
I hope I did not come off as pompous or arrogant.:engel017: Maybe sarcastic at best.:D Just making light of the question it was simply meant in gest and I hope you can see that. Please re-read my post. But if you still feel that way too bad.
 
Unfortunately not much you can do. The main problem is the location and the reflective walls that bounce sound all over the place. Rolling off Hi-end on EQ and some gating will help a little.
 
thanks photonashville,

your input is much appreciated. i will check out Barry Green's DVD that you recommend.

Dennis
 
C2V said:
Unfortunately, reverb - especially reverb that severe - cannot be tamed once it's recorded. Gating and compression can help, a little, but not to a point that you'll have a favorable end-product. Choreography rooms like that are almost like giant bathrooms in that they are the most unpleasing reverb chambers known to man, and there's not a whole lot you can do (short of hanging dozens of sound blankets) to deaden that kind of room.

Listening to the clip, though, it sounds like there was some serious compression/limiting on the signal. I can hear it clamp down on the claps and stomps, and then release with the reverb. That enhances the effect of the reverb as well. What else did you use to record (i.e. into what device was your shotgun mic connected... and which NTG)?

It's also worth noting that a shotgun in a room that reflective is not the best mic choice by far. You could try with a hypercardioid, or even PZM/boundary mics. You'll still record tons of the room's reflections, but they won't compound nearly as badly as with a shotgun.
Click to expand...

Thanks C2V,

This is the kind of information and response I've come to expect and appreciate on these dvxuser forums.

Your points and suggestions will help me to make better audio choices in the future.

Can you elaborate on what you mean by 'compression/limiting' on the signal? I was using a Rode NTG-2 microphone connected via 25 ft cable to input #2 on the xlr adapter of a Panasonic HMC40 camera. The microphone was running on phantom power from the cameras battery and mounted in a shock mount on the end of a C-stand 40" grip arm and pointed at the dancers feet. Here are the settings that I used on the xlr adapter: audio setup

Thanks again.

Dennis
 
mrmoe said:
Unfortunately not much you can do. The main problem is the location and the reflective walls that bounce sound all over the place. Rolling off Hi-end on EQ and some gating will help a little.
Click to expand...

Thanks mrmoe,

Your input is much appreciated.

Dennis
 
mrmoe said:
Unfortunately not much you can do. The main problem is the location and the reflective walls that bounce sound all over the place. Rolling off Hi-end on EQ and some gating will help a little.
Click to expand...
For that to have any you would need much more outboard equipment and run double system. You would need a gate. They are primarily rack mounted and learning it is not extremely difficult but does take some time to master. Furthermore trying this in post it would hardly be noticable because every hand clap and foot stomp hits on an echo in rhythm. So you would be reducing the actual signal you are trying to capture.

As for EQ, if you are trying to reduce it during production your mixer will need to have an on board eq. And if you are doing it in post it might help but you will also reduc the highs in the usable signal as well.

As for my original thought about the mic distance for your subject how far away were you from the dancer?

Also as for location, can you choose another location or reshoot this particular shot?
 
droliff said:
Can you elaborate on what you mean by 'compression/limiting' on the signal?
Click to expand...

There's a "breathing" or "pumping" in the audio. A compressor is designed to squeeze the dynamic range of the audio in the event of sudden peaks, in order to avoid distortion on the peaks. That also allows the low dips (whispers, etc.) to be brought up a little. A limiter is sort of like a compressor, in that it reduces the signal in the event of sudden peaks... but a limiter's function is not to reduce dynamic range, just to "limit" those peaks so they don't go over a certain point.

Heavy limiting or compression is painfully audible. You'll hear the sound squeeze at a peak, and then you can hear the limiter or compressor "release" the squeeze afterward. Does the HMC40 have and ALC setting, did you have it on, and where was your audio peaking on the meters while you recorded? Or did you try to apply any audio plug-in/filter in FCP before you posted this clip?
 
There is one reliable way to reduce the echo in post - record new footwork!

Perhaps your dancer would be willing to help you out by duplicating the footwork in a more acoustically-friendly environment?

You could record a stereo "perspective" (from the POV of the camera), and tape one (or two) tiny lav mics to the shoes (or something equally creative) and see what you get. Maybe there's someone you know who would be willing to help. It could be a fun challenge either way, and great way to focus on audio basics for a bit.

Just a thought.

Oh, and have fun with it.
 
Actually there is at least one "reduce echo" plugin, for Pro Tools anyway. And there are some things that can help. The plugin BTW has not gotten any rave reviews so it is probably just a multi band compressor.
As to things you can do. EQ may help, but probably not much. An expander gate set just right might help also. I say "just right" because it's a tricky thing to set and it is different on each set up. THe best tool is unfortunately not available for sale. Elemental Audio (then bought by Roger Nichols Digital and abandoned) made a level based multi band compressor. That was pretty good at reducing low level echos and leaving the higher level dialog.

Any "fix" depends on there being a significant level difference between what you want and what you don't. I haven't listened to your clip but it "sounds" like that may not be the case with your sound track. In which case you are probably SOL.
 
You could use a little compression on a duplicate track, reverse phase on the duplicate and mix them. Phase cancellation should bring down the echo a noticeable bit
 
There's some odd things about the sound which probably have to do with the fact that the mic is pointed towards the floor. Because of the nature of the material, this is a candidate for "foot over", where you just redo the audio and sync it back to the vid. If you can't shoot it over.
 
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