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Compression?


cinetj

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Hi,

I've just got my nomad. Really enjoyed the possibility of doing fine adjustements on the compressor and its transparency as well. Hence my question. How many of you, if any, use compression when recording, not only as a way of avoiding distortion (limiting) but to make dialog sound bigger and fuller?

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I do. What if there isn't any audio post?

Then production is making a choice to skip a vital step in the process. I could see this on sit down interviews and the like, but I still don't use the compressors for that in the field. It's too hard to accurately monitor in the field, and I don't know if/how they will edit etc...

Overload protection only here.

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In music tracking environments, I often use a "leveling" compressor to help keep the recorded vocals a bit more consistent. This compression is never used to have a "sound", just for basic leveling. I use very fast attack, low ratio, like 1:2 or 1:4 at most, soft knee, and set the threshold high enough so that it is not active most of the time, just acting on higher peaks... you could sort of think of it a progressive component of the peak limiter. I've been experimenting with the compressor built into the Zaxcom TRX900LT and LA transmitters and have been happy with their performance. It gives me a bit more room to ride dynamic passages with multiple people in unscripted environments, where I'd be hitting the limiter or worse, over modulating, more often. Compressors if abused, however, can impart unnatural artifacts that post will not be happy about. Also in general, compressors bring out the sound of the room more, especially when the threshold is set too low.

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Are we talking about narrative, or non narrative work here? I feel that the venue would certainly affect the decision to use effects like compression or more advanced equalization.

I don't see the venue as affecting the decision, but the specific production, their expectations, and their post flow all come into the equation.

However, even having said that, I mostly stay with the approach of "get it as clean and natural as possible" which usually just means some peak protection by way of limiting, and let post deal with shaping and mixing the sound as appropriate for the final product.

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From memory, choose the fastest attack, 2:1 ratio, soft knee engaged, and a threshold is completely situation dependent. If I had remote control, where I could monitor these settings from the QRX and adjust on the fly (Howy please), I could really dial in a setting. But as it is, you really can't expect to get the actors attention that long, have him deliver test lines, set gain, adjust compressor, repeat, rinse, so for the most part, the threshold stays set to something like -10dB for controlled sit down interviews. My limiter is set to -2dB. So in effect, I have a brick wall, presumably at infinite ratio at -2 and and additional -8 dB of some padding... where the signal is cut a few more dB before it actually engages the limiter. If my target is to keep my average around -20 with peaks at -10 or so, ideally the talent will just be tickling the compressor occasionally and turn those "oh shit" moments into "oh crap" situations instead... still bad, but I figure the compressor gives me about a syllable or so of additional reaction time to catch situations where I need to adjust gain levels. For unscripted reality type situations, I'd be inclined to set up my mixer with a few dB of "gain in hand" and shoot for lower average levels on the preamp gains, and make up for the loss with fader rides. I really don't think that the compressor should be used much, just a little bit to help you at the limits of your performance envelope with manual fader riding, and ultimately cannot be used as some sort of "auto mixer" feature, even though that idea is enticing for those of us without auto mix capable front ends.

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I would use this perhaps in interviews that I know will have no post work. Perhaps make a clean and processed track with routing when in doubt? I'd use for panel discussions and other "mix it all to mono on tape" type stuff, but again, only when there is absolutely no audio post in the workflow.

Generally a very transparent go-to setting I use in post is setting the threshold just above soft material. Moderate material should be pushing the threshold some, and loud material should have the compresson fully engaged. Fast or medium timings. 1:1.1 to 1:1.5 ratio, basically looking for a gain reduction of about 3db at the loudest parts. I find this type setting will avoid most pumping artifacts, acts good with voice on most compressors, and brings dynamics into what I would consider a natural range, getting rid of very loud fluctuations but not doing really bad things with your noise floor or risk pumping sounds.

Keep in mind, a lot of noise reduction is based around a constant noise level as the reference for noise removal. If you're compressing the voice, you're also bouncing the noise floor around. That can cause the noise reduction to not work well or to change the quality of the background noise in time with the speech patterns, adding strange effects. Same reason why post doesn't like volume riding.

When in doubt, go clean, but I for one REALY like having the option available if needed. Consider compression on IFB output to make noise problems more readily noticable when producers are listening at low volumes. I'm not sure what routing configs are available with Nomad, so I'm not sure what is or isn't available.

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What if there isn't any audio post?

Unless there isn't going to be any editing at all, leave the compressor off.

Even compressing in Avid/FCP is better than trying in the field... because the pix editor can play with the settings, or undo, or keep multiple versions. I'd also suspect that trying to set up a compressor under field conditions, wearing headphones, won't tell you as much about dynamics as even the poor speakers in an edit bay. Phones tend to make you overdo the final dynamic range since there are no distractions.

Of course if it's a once-in-a-lifetime with a wide and unpredictable dynamic range, or the producer says "I want this to sound like a finished track" and you can't persuade otherwise, all bets are off.

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Unless there isn't going to be any editing at all, leave the compressor off.

Even compressing in Avid/FCP is better than trying in the field... because the pix editor can play with the settings, or undo, or keep multiple versions.

It's so wonderful that we have this forum... and the opportunity to disagree. Creative pic editors don't know SHIT about audio!

How about a radio broadcast when there is no pic at all?

I have to add... "it depends!"

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Creative pic editors don't know SHIT about audio!

That's frequently true. ("Frequently" rather than "always"... for example, there's this very creative pix editor named Murch...)

But I stand by what I said. If the project is going to be mixed in Avid, then the producer will be sitting there and can make the final "too much /not enough / undo and start again" decisions. And since the producer is the one who decided to forego audio post, he or she can be the person who determines the result.

Why deprive the producer of an opportunity to screw things up their own way? That's what they live for.

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That's frequently true. ("Frequently" rather than "always"... for example, there's this very creative pix editor named Murch...)

But I stand by what I said. If the project is going to be mixed in Avid, then the producer will be sitting there and can make the final "too much /not enough / undo and start again" decisions. And since the producer is the one who decided to forego audio post, he or she can be the person who determines the result.

Why deprive the producer of an opportunity to screw things up their own way? That's what they live for.

I mostly agree with your sentiments with respect to applying compression in the field vs post, but I think that the way that it can be used here can be beneficial, especially in less than optimal situations. We are talking about a very slight leveling process, rather than compression for effect or for finishing. In ideal situations, the sound power levels involved should be below the threshold of the compressor, so for the most part, it is out. When we start seeing levels that are above the threshold of the compressor and it starts working, first off, it should be as close to transparent as possible. Secondly, the alternative is to either consistently keep levels down to a much safer range, which would increase noise floor and sometimes give editors levels lower than they would like to see or to risk over modulation or activation of a brick wall limiter, a much less desirable outcome. That is to say, the compressor should be set for a range where the audio is already compromised or about to be compromised regardless and should be thought of as a different process than one you would apply in post. Compression for effect or for heavy handed leveling - absolutely not in the field of course. Having remote control of the preamp in the case of Zaxcom transmitters, makes a case for using the compression where in the past it would not have been an option or advisable due to the lack of control.

Should you run sound so that your consistently about to hit the brick wall limiter? No of course not, but for reality situations or 1-man mix / boom gigs, it's going to happen. In those instances I'd rather have a little bit of a safety net prior to the limiter kicking in. Even for cart / multi-crew narrative, it happens, just can't be helped with unexpected performances and the dynamic range of the human voice.

I would argue that the quality of the recorded audio file will be better with properly applied compression when you have compromised situations that exceed your ability / equipment / manpower / set conditions to address with fader rides alone.

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