Looking for audio assistance

YesMaestro wrote on 2/2/2014, 9:44 PM
I was asked to film a recital and it was performed at a local high school so the audio mixer was manned by a teenager. When I got the line feed from him when I set up, everything sounded fine. But when the show started the feed I was getting was distorted. Unfortunately I couldn't go back to him to see what the issue was as I was the only cameraman. Does anyone think there is a software (iZotope???) that could help with this?



musicvid10 wrote on 2/2/2014, 9:56 PM
A few portions of the first 22 minutes may be salvageable; unfortunately, the last 17 minutes seem to be unrecoverable by any means. Sorry to be the bearer of bad news.

Teenage tech monkeys need training. This goes double for sound board ops.

John222 wrote on 2/3/2014, 8:39 AM
Did it sound that clipped live? Or did the sound guy just overload the recorder input.

I usually use my Tascan Dr-2d recorder with an attenuator cable to get a board signal. A nice feature is it's 4 channel and can record a 2nd track at 6 or 12db lower input volume. I use this as a safety. When they don't let me use the board I put it on a mini pod near the front of the stage. I've done several high school things and they always mess it up.
Steve Mann wrote on 2/3/2014, 9:07 AM
For future reference, NEVER rely on a single source of sound in a live stage production.
Grazie wrote on 2/3/2014, 9:18 AM
Spent 20 minutes with it in iZotope RX3 Advanced - can't do it.


vtxrocketeer wrote on 2/3/2014, 12:06 PM
I just had nearly an identical experience, but in this case a professional was on the board. Line out to my line level inputs, but I still heard clipping, even though house sound was perfect. It was just a simple matter of turning down the board line-outs. Not the pro's fault.

Another production did have high schoolers running the board, including a mess of wireless mics that suffered immensely. The wireless channel was a disaster of dropouts, fuzz, and spikes, and my own stage mics saved the day. I used Izotope to excellent effect to salvage just some of the mildest digital spikes and fuzz. Everything else from house sound was trash.

Lesson: use backup mics, record backup tracks (i.e., two cards, separate device, etc.), attend one or more tech rehearsals. Fixing clipped audio in post is dicey at best.
Grazie wrote on 2/3/2014, 12:18 PM
My rule ONE: Audio is MORE important than the VIDEO!

Yeah, I know it is a sweeping statement, but it always puts me in the correct state of mind/thinking . . .

My rule TWO: Light is EVERYTHING!

Simples . . . . .


(PS: Where do I send my invoice?)

musicvid10 wrote on 2/3/2014, 12:22 PM
I always carry a pair of little Matchbox25 direct boxes in my kit. They will pay for themselves the first time you use them.

Besides -20dB, -40dB attenuation, they convert balanced to unbalanced, and have a ground lift switch to take out the hum. I never leave home without them ;?)

Note: There are bigger, more elegant solutions ( UltraDI), but the Matchbox25 is tiny and unobtrusive when you're hooking to a board.
Jumping Rascal wrote on 2/3/2014, 12:53 PM
I have spend some time recently attempting to fix up the audio portion of a 1980s church VHS concert tape was in bad shape/recorded poorly with distortion and found that a combination of audacity (free download) and vegas audio tools often can do a reasonable job of repairing and/or refocusing the audio to minimize the nasty parts. For your clip, the amount of distortion is very heavy but I tried applying audacity fixclip, equalization acoustic, normalize at -5, and then reverb at 0 from the defaults. After this in vegas, I applied audio restoration, gsnap, and paragraphic EQ (remove low rumble). The annoying spikes at the beginning can be chopped out manually. The outcome was not wonderful but was better. By the way, I found out that the small audience for my restored video was so happy with having a nice remembrance of the event on DVD that my less than perfect 5.1 audio restoration in parts was overlooked. I hope that you can find somebody who made an audio recording of the recital to combine with your video....all the best of luck on this!
Chienworks wrote on 2/3/2014, 1:43 PM
About a year ago i got called last minute to do a very low-grade freebie, single speaker wanted mic'd and video'd. I didn't have time to set up a real system so i grabbed a powered mixer, mic, stand, speaker, cables, and camera. When i got there and set up i realized i had my M-Audio Transit in the backpack with my laptop so i figured i'd record line out from the mixer as a backup to the camera audio. The signal looked rather hot so i turned down the gain to get it peaking around -3dB, then ran back to the camera just in time to start it running.

I discovered two things: 1) the recording output of the powered mixer was about 20dB hotter than most "line level" signals, and 2) the volume control on the Transit is after the digital stage, not on the analog stage, so the hot distorted signal was was digitized first, then the fuzz reduced in volume. It was completely unusable. Fortunately the camera audio was acceptable.

YesMaestro wrote on 2/3/2014, 4:03 PM
It did sound clipped once the show started so the sound op must have done something. But like I said, I couldn't go back and leave the camera unmanned. I do have another channel but that was a room mic so the sound is hollow. Thanks for the effort Grazie, I really appreciate it. I was hoping that it could be improved even just a little bit.
johnmeyer wrote on 2/3/2014, 4:47 PM
See if this is any better:

Singer (somewhat restored).wav

You'll have to adjust the volume to suit your taste.

[edit]Look at my post below for a slightly better version ...[/end edit]
richard-amirault wrote on 2/3/2014, 7:53 PM
Ways to deal with "hot" sound are good, but understand (as most of you here do) that if, anywhere in the chain *before* it gets to you, it gets clipped (and thus distorted) there isn't much you can do.

Yes, you can tweak it, and with the right tools you might make it sound better, but it will never sound like it could have (should have)
willqen wrote on 2/3/2014, 8:02 PM
Has anyone tried Sound Forge's Peak Repair?

May take some time but if the audio is absolutely required this tool can accomplish miracles.

At least it has for me.

The trade off is always the time spent vs the amount of result.

Might consider it ...



PS: I just looked at the file. It's not possible with Peak Repair.

The audio file is too large with too much distortion, too many clipped peaks.

Peak Repair, while very good at what it does, is too slow of work flow for this project/audio file.

It would take more than 1 lifespan to repair this audio file with Peak Repair ...

TeetimeNC wrote on 2/3/2014, 9:21 PM
>See if this is any better:

John, that sounds better than I would have expected could be done. How did you do it?

YesMaestro wrote on 2/3/2014, 9:37 PM
That does sound great John! How did you do it? I have approximately 22min that needs fixing?
johnmeyer wrote on 2/3/2014, 10:23 PM
I simply used iZotope RX3 clipped peak restoration. The settings were a little tricky to get just right.

The file I uploaded still has some bass thunks in spots, and a few residual clips. Those could be repaired manually in iZotope. Here are the settings I used in iZotope RX3:

I just ran it again, using exactly the settings shown above, and then followed that by using the Click and Crackle module, but modified heavily so that it finds and removes the "thumps" that happen when the bass overloads everything, just prior to the singing. Here's the result from that:

Singer Restored

The only really bad section left is on the word "reveille." If this was a job for money, I'd restore everything except that section and then try different settings on that one spot until I got a better result.

Grazie wrote on 2/3/2014, 10:44 PM
The settings were a little tricky to get just right.I started with the most challenging areas first. I got down to realms of those low DBs and had that rather unpleasant, you call "thumps" too, and decided to move on.

Looking at the curves, really liked the "smoothed-out" rounded waveforms - nice!

This product gets better and better.



johnmeyer wrote on 2/3/2014, 10:53 PM
Here are the settings for the "de-thumping:"

[edit]I would be happy to apply these two functions to the entire file. I don't have time to do local cleanup or manual restoration of the portions that fail. Also, it will be up to you to normalize/EQ/balance the resulting audio file.
Grazie wrote on 2/3/2014, 11:04 PM
John, what you've done is to invite me to re-order the task/workflow in hand and push iZo.

Is there ANYTHING it can't do?

Just used your de-thump and picked up 14 "clicks" on an area.


John_Cline wrote on 2/3/2014, 11:31 PM
Izotope RX3 Advanced is as close to "miracle software" as one can get, too bad there isn't something like it for video.
YesMaestro wrote on 2/4/2014, 12:57 PM
Thanks John! I really appreciate the effort. This program is definitely amazing.
John222 wrote on 2/5/2014, 7:38 AM
Hey musicvid10, the Rolls Matchbox looks like a great idea. I did a search and found two versions... One had the 0 - 20 - 40db switch (like yours) and the other have a variable attenuator. Which would you recommend? I'm currently using a 20db Sescom LN2MIC, whichs works great, except a ground lift would be very nice.
TeetimeNC wrote on 2/5/2014, 9:41 AM
Musicvid, I'm curious that you use the matchboxes routinely when connecting to a soundboard. I only occasionally get an audio feed and haven't yet been bitten by the hum issue. And I naively thought "line out" was a "standard", but it sounds like there may be some situations where I will need attenuation. I would appreciate your thoughts on what you have encountered that prompts you to use these routinely.

johnmeyer wrote on 2/5/2014, 11:01 AM
"Line Level" is sort of a standard but the problem is that many soundboard feeds actually give you a headphone output which is something a little bit different. Not only can it be hotter than line level, but it is a variable output, meaning that during the performance someone at the board can accidentally tweak the levels.

Hum is almost guaranteed when running from a soundboard using any of the unbalanced outputs. My "solution" to this is to use an audio/video to Cat5 converter like this:

Composite Video and Audio Over CAT5 Extender

This not only completely eliminates any ground loops, but it lets me set up a long way from the sound board. I carry several hundred feet of Cat5 cable with me which I then use to make the connection with one of these converters on each end. Cat5 cable is exceptionally easy to gaffe-tape to the floor, so setup is quick.

This doesn't provide any solution to the overload, so you still need to look at musicvid's excellent suggestions (I'm looking at that one for myself).