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Exporting Neverclip files from recorder. Please explain?


Lids

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Lately I and a few other colleagues have encountered some strange distortion issues in the dialogue recordings of recent film jobs (we are in sound post using protools). The one common denominator seems to be that the recordists have used Zaxcom recorders and the "neverclip" function. I can't pretend to be very literate about recorders, but we're wondering if there might be a transfer issue from the recorder that is preventing us from hearing that extra headroom and is thus causing the clips to sound distorted/compressed? I guess my question is can someone explain the details of Neverclip and the export process to someone who doesn't know the equipment so we can ask the sound recordist the correct questions. 

Any help is appreciated, it'd be great to get to the bottom of this!

Thank you! 

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I think it would be best, by the sounds of it, for you and the mixer to contact Zaxcom directly. Get an answer from the horses mouth, so to speak once you have exhausted other areas of possibility for the distortion. There are also a lot more things we would need to know, like what recorder are they using? What is their setup within that recorder? etc, etc...Is the distortion happening at the mic, or the mics plug on transmitter, or the analog mixer first before it goes into the zaxcom recorder?

 

I use zaxcom recorders all the time and they all have Neverclip. It is more a process that helps make sure you don't distort the audio coming into the inputs of the recorder itself. It is a bit shifting thing and there are 4 extra bits that can kick in if there is a signal that is too hot for the first 24 bits to handle. If too hot it can use the 4 extra bits to give you sort of a 28 bit recording and therefore more headroom and dynamic range and side stepping the distorted audio at the input into the recorder. That is my understanding of it anyway. I could have that completely wrong. Regardless it is supposed to give you some breathing room if a hot signal comes in. Of course, you can still distort your analog channel on your mixer, for example, and there is no saving that. It will be recorded sounding distorted regardless of neverclip.

 

Exporting files is done through a conversion process within the recorder and converts from Zaxcom's proprietary MARF file to the BWF files onto a CF card, handed to the DIT, and then on to you that you receive to put into your Pro tools session. Neverclip, as I understand it, does not come into play in the conversion process. It is only working at time of recording the audio on set as it is going on to the main hard drive, or main CF card of the recorder. Then the mixer chooses how it gets converted to be sent to you.

 

Please correct me if I am wrong about how Neverclip works guys.

Hope that helps.

CRAIG

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Never clip works at the input of the analog channel as Craig describes.  Gain structure is still important as its possible to distort the output busses and/or the card tracks if the signal is too hot going to them and/or hit the compressors too hard.  If they are using the input compressors and hitting them too hard that's another place distortion could be coming from.  On my Nomad I don't use the input compressors at all, but do use the card and output compressors.  
As Craig noted it would be best to contact Zaxcom directly in tandem with the mixers on the job.  

Out of curiosity how do the iso levels and mix levels look?  If you zoom into the waveform are the peaks squared off, or do they look normal but sound distorted?  I've worked some very loud events with my Nomad recorder and I've rarely if ever had distortion occur within the device.

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Neverclip uses dual A/D converters in tandem to expand the dynamic range of an analog input. It's main purpose is circumvent the use of input limiters that may produce distortion when engaged. It's most effective if the ISO track has Neverclip attenuation set to it.

 

For example, you have one boom mic and it's ISO track is Neverclip attenuated 12 dB. You have it routed post fade to Mix Bus 1 and accidentally crash into the Mix bus 1 Compressor (you didn't fade back on cue). Well, the ISO track has 12dB of headroom that post can now use to treat the problem area of the mix.

 

It's only effective if the mixer in the field knows how to use it.

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Lids says: "Lately I and a few other colleagues have encountered some strange distortion issues in the dialogue recordings of recent film jobs (we are in sound post using protools). The one common denominator seems to be that the recordists have used Zaxcom recorders and the "neverclip" function"

 

Question: once determined that the tracks that you have had a distorsion problem came from sound mixers using Zaxcom recorders, did you speak with any of these sound mixers? I'm sure you have had distortion issues on occassion on some films where the sound mixer was using some other recorder (typically a Sound Devices recorder)  ---  did you ever follow up speaking to those sound mixers to determine the source of the distortion? It is commendable that you wish to understand the inner-workings of Neverclip in Zaxcom recorders, but your assumption that the distorsion you have heard is a result of Neverclip is highly unlikely. It is possible that the sound mixers using the Zaxcom recorders as you state, may not themselves understand Neverclip and are making critical mistakes in their gain staging thinking that whatever they do, Neverclip will save them. As many have stated here, Neverclip when used properly will be highly effective in protecting the ISO tracks but it is still very easy to overload or clip a mix track resulting in distorsion. Of course if the signal coming into the recorder input is distorted or compromised in any way (the source being a wireless transmission for example that is already into limiting or distorsion  ---  Neverclip on the input will not help out in this case, the recorder will just faithfully record the signal.

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On 10/27/2019 at 9:45 AM, Lids said:

Lately I and a few other colleagues have encountered some strange distortion issues in the dialogue recordings of recent film jobs (we are in sound post using protools). The one common denominator seems to be that the recordists have used Zaxcom recorders and the "neverclip" function. I can't pretend to be very literate about recorders, but we're wondering if there might be a transfer issue from the recorder that is preventing us from hearing that extra headroom and is thus causing the clips to sound distorted/compressed? I guess my question is can someone explain the details of Neverclip and the export process to someone who doesn't know the equipment so we can ask the sound recordist the correct questions. 

Any help is appreciated, it'd be great to get to the bottom of this!

Thank you! 

What is your real name?

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On 10/29/2019 at 2:53 PM, Jeff Wexler said:

but your assumption that the distorsion you have heard is a result of Neverclip is highly unlikely.


I don’t think it’s fair to say that Lids is actually making that assumption. It seems to me like this is an area they don’t understand and they wish to have more information so they can actually make the assumption...

 

I‘ve had issues with NeverClip on a transmitter in the past. It may have been fixed by now and it may have been exclusive to that transmitter (742), but I could hear a noise artifact whenever one converter process was switching to the other converter. This was confirmed by Howie at Zaxcom, although I should note that I have only heard this confirmation from another mixer. That certainly was a strange sound...

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So in summery, based on reading the replies - ‘neverclip’ doesn’t actually do that - It’s a tool that when used correctly ( which exactly how seems to be difficult to explain ) can help prevent clipping.

 

Thus recordists with this facility, expect it to prevent clipping, run hot levels, and what you’re hearin’ is good old fashioned distortion from limiters.  

 

I presume this also because I went thru the same thing, and instead use gain staging ( and Sonosax limiters )

 

regards

 

 

 

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Neverclip is a great name, but not a great description. With this, or any other technology, there is no substitute for proper gain-staging.

 

Unfortunately, many in a new crop of sound mixers simply want a magic bullet for everything. One of the latest shiny objects is 32-bit floating point processing. While I certainly champion its long-standing benefits in post production mixing, there are production mixers who anticipate that its implementation in their gear will alleviate them from the burdensome task of actually learning how audio works.

 

There is no substitute for knowing your craft. Learn, and use, proper gain-staging for Neverclip, 32-bit floating point processing, or any other advanced technology. Too many don't understand that gain-staging isn't just about how you set the knobs, it's about understanding the parameters of all circuit stages before, and after, those simple knobs. 

 

And while internally some devices are more forgiving due to increased dynamic range, what we deliver must still respect the digital "brick wall" -- against which all will shatter. 

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Thank you, John B., for the thoughtful and realistic explanation regarding this Neverclip issue. I was wanting to weigh in on the issue as it relates to other technologies, like 32-bit floating point, and point out as you have that sometimes the names and descriptions, and in some instances the marketing hype, can unduly influence some of our less experienced sound professionals. 

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On 10/28/2019 at 5:45 AM, Lids said:

Lately I and a few other colleagues have encountered some strange distortion issues in the dialogue recordings of recent film jobs (we are in sound post using protools). The one common denominator seems to be that the recordists have used Zaxcom recorders and the "neverclip" function. I can't pretend to be very literate about recorders, but we're wondering if there might be a transfer issue from the recorder that is preventing us from hearing that extra headroom and is thus causing the clips to sound distorted/compressed? I guess my question is can someone explain the details of Neverclip and the export process to someone who doesn't know the equipment so we can ask the sound recordist the correct questions. 

Any help is appreciated, it'd be great to get to the bottom of this!

Thank you! 

HI Lids - By process of elimination try the following.

 

Contact the recordists and ask what wireless systems they are using. The distortion maybe in the transmitter or even microphone or simply too hot

 

If it is zaxcom wireless then check the SD card recording against the iso track on the recorder to see if there are differences.

 

Most Recordists would have their contact details on their sound report. They would be able to answer many questions and probably remember the scenes in question.

 

Without confirming all of the equipment used on the scene's affected, its unwise to assume its the recorder. 

 

Tony

 

 

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There are threads here that explain how Neverclip(tm) works, and in a nutshell it uses two a/d converters to extend the possible dynamic range of an analogue input of the recorder. Now, this only works if it is set up properly (no input compressors, compressors on card tracks and/or output busses, activated ISO ATTENUATION) Note that it only extends the ad dynamic range of an analog input so it is not responsible for distortion that comes before that input - eg., from a wireless transmitter (most likely), or wireless receiver. Are the radios recorded to analog ins or digital ins of the Zaxcom recorder? Too many variables to tell. 

 

Contact the mixer, let him explain. Do workflow tests together if he's unsure. Yeah a bit too late for that, but at least you'll learn something for the next shoot. And please, do not bother Zaxcom with stuff that is available in the manual and on this very forum (and youtube, Glenn Sanders and others talked about ways of using neverclip for many years now)

 

Be well.

 

Bartosz

 

 

 

 

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Thanks all, most of your comments were very helpful. 

Here's another question: Can you change the settings on the export of recordings FROM the recorder (or SD card) and would that ultimately make any difference to what I would get as a dialogue editor? There was one job in particular where we did actually ask the sound recordist to listen to their tracks and tell us if they were distorting on the recorder, to which they said that they weren't. I wonder in hindsight, now, knowing a smidge more, whether we should've asked what the export settings on the recorder were and whether it would've made a difference had they been set differently? Is this worth exploring in your opinions?

 

 

 

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