Serious Audio Distortion - Need Help Bad!

G

Grasshopper

Member
I just went through the tapes of my last shoot and the audio has a terrible electronic type distortion occurring randomly throughout the footage.

It was shot on a dvx and I used two separate microphones
- Input 1 was from a lecstronic wireless mic that I rented
- Input 2 was from a shotgun mic (just in case as a back up)
The distortion is on both channels, so it's not the mics.

I tried importing into final cut from 2 different cameras, different fire wire cables, but to no avail.

Sometimes if I reimport the footage the strange blips will occur at different points in the footage.

I'd like to post a sample so someone can hear what I'm talking about, but not sure how to post one in this thread.

Any help would be much appreciated.

Thanks.
 
Grasshopper said:
I just went through the tapes of my last shoot and the audio has a terrible electronic type distortion occurring randomly throughout the footage.

It was shot on a dvx and I used two separate microphones
- Input 1 was from a lecstronic wireless mic that I rented
- Input 2 was from a shotgun mic (just in case as a back up)
The distortion is on both channels, so it's not the mics.

I tried importing into final cut from 2 different cameras, different fire wire cables, but to no avail.

Sometimes if I reimport the footage the strange blips will occur at different points in the footage.

I'd like to post a sample so someone can hear what I'm talking about, but not sure how to post one in this thread.

Any help would be much appreciated.

Thanks.
Click to expand...

Before you panic, the first thing to do is to hookup some headphones to your DVX and playback the tapes. Is the distortion on the tapes? Or has it been introduced in logging and capturing?

Dan
 
Grasshopper said:
I just went through the tapes of my last shoot and the audio has a terrible electronic type distortion occurring randomly throughout the footage.

It was shot on a dvx and I used two separate microphones
- Input 1 was from a lecstronic wireless mic that I rented
- Input 2 was from a shotgun mic (just in case as a back up)
The distortion is on both channels, so it's not the mics.

I tried importing into final cut from 2 different cameras, different fire wire cables, but to no avail.

Sometimes if I reimport the footage the strange blips will occur at different points in the footage.

I'd like to post a sample so someone can hear what I'm talking about, but not sure how to post one in this thread.

Any help would be much appreciated.

Thanks.
Click to expand...

I think what you'd have to do is put the audio clip up on a website somewhere, then post a link to it.

If you're right -- that the distortion appears in different places on the tapes during separate imports -- then that sounds like a good sign. It would indicate, I think, that the distortion is not on the tapes themselves, but somehow is being introduced during the capture process.

Can you get someone else to do a test capture using their equipment, and see if they get the same distortion? Or can you capture using a different camera or deck, something other than your DVX?
 
With a dvx I'm pretty sure it's possible to route the signal from one mic input to both audio tracks, do you remember setting the mic inputs? If that had inadvertently happened the noise may have been cause by RF interference hits on your lectrosonics operating range. Kind of a long shot but a definite possibility. Even if you could just post some of the audio from the tape would be very helpful. I agree with trying to monitor off the camera to see if its on the tape are was introduced elsewhere before doing anything else.
- oh and what kind of shotgun was it?
 
Here is a link to the distortion:

www.theministryentertainment.com/audio.html

You can hear it clearly as the girl says" trying to get that stretch"

It's pretty rampant thoughout the rest of the footage.

It sounds like aliens are trying to communicate with me through my dvx. I wish they's just try my cellphone.

I listened through the headphones and it seems like it is there, although less pronounced.

I tried cleaning the heads on my cameras and reimported, but still there.

This had happened to me before a few years back, but I had done a few music videos since then and the camera audio wasn't used in the final output.

If I recall correctly, it never happens when using the built in mic, just when using the xlr inputs.

I don't care if I have to have her do overdubs on the entire project, I would just like to figure out what's causing this so it doens't happen again. Very disconcerting.

Oh and the shotgun was a Sony ECM I think
 
You were listening when you shot this right? I'm going to assume someone was, if not don't do that again... If it was the mic whoever was listening should have heard it. The fact that it seems to be moving around probably means it's a transfer problem.
With that in mind are your capture settings set up correctly? Is the noise short and repeating or just long and nasty. Since you tried different cameras I would look to the computer and stuff connected to it or around it. Is it connected to the internet? Are you downloading a bitstream in the background?, checking mail etc. If the shielding isn't good it might be poss for things like your iPhone or Blackberry pump noise in when they call home, which they do periodically.
I would try a transfer in a very clean set up. NOTHING in the background and put the cel phones in another room, no internet connection etc. And when I say nothing in the BG remember that things like spotlight will be working in the BG unless you turn it off with something like spotless.
 
THis sounds like squelch on a receiver. If we assume that for some reason the wireless was going to both channels that could be your problem. With old wireless systems we used to get this with low batteries. This was theatre and we would use old ones for rehearsals. This would happen if the cells were low and it also happens almost instantly with any kind of rechargeable (since they start out low 1.2V as opposed to 1.5V). Were you using rechargeable or old batteries?
 
The noises are short, but persist throughout at random points. I was the dummy with the headset on and was sure I didn't hear it on the set. But even now as I listen to playback on the dvx through the headphones it is not so easy to pick up the distortion. Maybe bad headphone or ears, but definitely a good reason to have a dedicated sound guy on the set.

The receiver was connected to input 1 and the shotgun to input 2 through a long xlr cable. It's strange that it would be distorted on both channels.

The computer that I am capturing on is not connected to the internet, but there is wifi in the area.

I'm usung the same mq tape stock also. I should have access to a different computer later and will try to capture there.

I appreciate you guys helping out. It is kind to share your knowledge.

Great Forum!
 
Assuming the distortion is on the tape, I agree with Noiz 2, sounds like some kind of wireless issue. I can sympathize, how else could you have miked it? I would test the wireless system in the same place. As batteries die or lose power, I have experienced this, even with wired mics.

How long had the batteries in the wireless mic system been in use when you first hear this on the tape? What kind of wireless system? Generally, I try to change the batteries in the wireless about once every 3-4 hours and I try to turn them off during breaks.

Good luck and let us know. If it's on your tape, you are stuck but perhaps we can figure out what caused it at least so you don't get hosed by it again.

Dan
 
This is a broadband squelch kind of sound and no filter is really going to fix it. But there is also a dropout just before the noise so even if you got the noise out you would have a problem.

I would normally just paste RT over this kind of noise to get rid of it. Fixing the drop out and what you had to get rid of because of noise could be hard to near impossible. First you would need to come up with a list of words / syllables that need replacing and then go looking through footage to see if you can find some replacements. If you can then it's not too bad. If you have to try and recreate words from snips of other words in gets ugly fast. It really depends on how many of these hits happen on words. If it's a lot then maybe looping is a better choice.
 
Thanks, I think you are right about the filters...from what I've played with so far, no luck.

I have the same shots from different angles where she says approximately the same thing. So chances are I'll be able to pick up missing words somewhere in the footage. Plus during much of the dialouge her face isn't completely visible, so synching shouldn't be much of an issue.

I wonder if I could have some kind of bum audio inputs or something on my dvx.

This is the 2nd project that this has happened to me on and the 1st one wasn't a wireless mic.

Has anyone experiences this type of distortion before?
 
Yeah, I think that's my only option.

If anyone has experienced this kind of distortion using the xlr inputs, please let me know what caused it so I can avoid this in the future.

Thanks.
 
You must log in or register to reply here.
Back
Top