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Declip, snake oil?
Old 14th April 2008
  #1
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jahtao's Avatar
 

Declip, snake oil?

Greetings,

Out of curiosity, just had a really quick go on Izotope RX declip and.... rubbish! : )

I challenge anyone to produce before and after files of successful declipping!

I can't understand how such a thing is possible. I mean, I if over expose a digital image how is it possible to know what its a picture of?

Matt
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Old 14th April 2008
  #2
Gear Head
 
havlowjumper's Avatar
 

I humbly disagree. Been using it all day today as a matter of fact. I think it needs to be a quick period of clipping for it to be most effective. My guess with how it works is it looks for periods of clipped audio and then redraws the waveform based on how the wave looks before and after the clipping (again better with a short period of clipping) If the file is totally flatlined (your overexposed analogy) than yeah, you are probably in trouble.

Admittedly there are still some artifacts from the declip process, but in some instances masking those artifacts is a better alternative (or the only alternative) to getting a new take.

my 2 cents,
-Abe
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Old 14th April 2008 | Show parent
  #3
Gear Maniac
Has been working well for me, within limits.
Badly distorted audio will NOT be fixable.
Also the -8dB threshhold is fairly useless.
I have found myself adding gain to bring the clipped portion of the audio into the usable region (0db to -8dB), declipping with some gain reduction for peaks in the declip module, then reducing gain back to original levels, taking into account the gain reduction from the declip module and making up the difference with the gain module.
Also, I have found declipping followed by declicking to work well sometimes.
Admittedly, the settings are finicky and need some careful knob twiddling to get good results.

Hope that helps.
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Old 14th April 2008 | Show parent
  #4
Gear Maniac
 

I've had good results using the Spectral editing function in Samplitude to fix clipped audio. Samp has a declip feature as well but I didn't find I got good results with it so instead I opened up the voice dialog in the spectral editing and saw the clipped lines appearing as weird square patterns. I highlighted the clipping patterns and reduced their level until the "edge" dissapeared. Worked amazingly well and far better than the official declipper tool.
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Old 15th April 2008 | Show parent
  #5
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peeder's Avatar
 

I love the RX declipper. Spectral repair for the longer problems. You need to know how to work the params and such.
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Old 29th January 2009 | Show parent
  #6
Gear Addict
 

I've been using it extensively on a horror feature recently. Works perfectly well for screams!
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Old 29th January 2009 | Show parent
  #7
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DrDeltaM's Avatar
 

All depends on how much useful data is still in the nonclipped audio portion. Can you post a sample of your problem?

When something is so heavily clipped that there's little usable signal left, nothing can fix it, as you'd have to 'reinvent' it almost completely.
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Old 29th January 2009 | Show parent
  #8
Gear Guru
 
charles maynes's Avatar
 

I have used successfully on a number of occasions- to say it works everytime is subjective, but it will likely be better than the original- I also REALLY like the Oxford declicker...
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Old 29th January 2009 | Show parent
  #9
Lives for gear
 

All the declippers I've used seem to want to see a really flat-topped waveform in order to be able to "grab" it. I haven't found a hard and fast rule about what will work and what won't, but it's usually worth a try. Another way to do this same work is to reshape the clipped peak in an app like reNOVAtor or ReTouch.

Philip Perkins
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Old 30th January 2009 | Show parent
  #10
Gear Maniac
 
bizzle's Avatar
 

Waves X-Crackle usually works great for distorted production. I have had only occasional success with the iZ de-clipper.
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Old 30th January 2009
  #11
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BIGBANGBUZZ's Avatar
 

Quote:
Originally Posted by jahtao View Post
Greetings,

Out of curiosity, just had a really quick go on Izotope RX declip and.... rubbish! : )

I challenge anyone to produce before and after files of successful declipping!

I can't understand how such a thing is possible. I mean, I if over expose a digital image how is it possible to know what its a picture of?

Matt
Izotope seem to only work on square wave digital clips, I have had no help with Izotope on analog type distortions, or anything with a saw tooth type artifacts in the waveform.
Izotope does work, but only on certain types of clips.. which is a real bummer.
Try zooming on the wave forms with Spectral repair. and hitting repair, I just fixed some distorted vo recorded by a video editor using it.
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Old 30th January 2009 | Show parent
  #12
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DrDeltaM's Avatar
 

Quote:
Originally Posted by bizzle View Post
Waves X-Crackle usually works great for distorted production. I have had only occasional success with the iZ de-clipper.
There's different types of solutions for different types of distortion. I too use declick & deccrackle for removing some types of distortion, works great (using Cedar Declickle).

But for distortion coming from clipping (or similar), Cedar Declip usually delivers, unless the file is simply waay too damaged, then you can't expect a full fix, tho an improvement is still possible.
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Old 30th January 2009 | Show parent
  #13
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jahtao's Avatar
 

As the originator of this thread way back when I feel i should point out that I have seen the light. After wow-ing myself, my boss and some rather anxious clients I am now a believer! For me the secret was to submit to the mysetries of pot luck: try enough different settings and you should strike gold. Different settings for different distroted syllables, and combine different renders to get rid of all the distortion through out the whole passage.

Some material it just won't work on at all for some reason.

I've also chopped out all the sibilants and put them on a separate track, and used an expander... and EQ obviously... in conjunction with the undistort, on bad sound. The results can be very pleasing
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Old 30th January 2009 | Show parent
  #14
Lives for gear
 

Quote:
Originally Posted by jahtao View Post
As the originator of this thread way back when I feel i should point out that I have seen the light. After wow-ing myself, my boss and some rather anxious clients I am now a believer! For me the secret was to submit to the mysetries of pot luck: try enough different settings and you should strike gold. Different settings for different distroted syllables, and combine different renders to get rid of all the distortion through out the whole passage.

Some material it just won't work on at all for some reason.

I've also chopped out all the sibilants and put them on a separate track, and used an expander... and EQ obviously... in conjunction with the undistort, on bad sound. The results can be very pleasing
This is pretty much my experience--sometimes it works and sometimes it doesn't, and I've never been able to predict the results based on the sound of the original file. I'm just glad it works sometimes!

Philip Perkins
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Old 30th January 2009 | Show parent
  #15
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Alexey Lukin's Avatar
 

Here is one before/after declipping sample that I've done with RX recently: 2 links after the images.
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Old 1st February 2009 | Show parent
  #16
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jahtao's Avatar
 

Quote:
Originally Posted by philper View Post
I've never been able to predict the results based on the sound of the original file.

Philip Perkins
Good (key) point, nice Phil
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Old 2nd February 2009 | Show parent
  #17
The very fact that this discussion is even taking place says much more to me than I like to hear. Like "Why are we being expected to work with such dreadfully badly recorded sound in the first place?" and "Why was this passed and not ADR/dubbed/re-recorded"?
Would the picture editor accept a shot that was overexposed with bad lighting?
Of course not - so why should we take this?

Perhaps the real question should be "Why is this happening in the first place"?
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Old 2nd February 2009 | Show parent
  #18
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Quote:
Originally Posted by neilwilkes View Post
Perhaps the real question should be "Why is this happening in the first place"?
Because they're more willing to pay for catering than audio? (no offense to catering, its not their fault)
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Old 2nd February 2009 | Show parent
  #19
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Henchman's Avatar
Quote:
Originally Posted by neilwilkes View Post
The very fact that this discussion is even taking place says much more to me than I like to hear. Like "Why are we being expected to work with such dreadfully badly recorded sound in the first place?" and "Why was this passed and not ADR/dubbed/re-recorded"?
Would the picture editor accept a shot that was overexposed with bad lighting?
Of course not - so why should we take this?

Perhaps the real question should be "Why is this happening in the first place"?
Because this is simply the way it is with low-budget movies and TV shows.
And underexposed shots ARE being accepted now. People are shooting with malfunctioning cameras, and trying to fix it in Video-Post, because they were too cheap to budget the show properly in the first place.

I swear, some of the reality TV shows I've worked on have better sound and picture than TV Drama shows they are trying to do for such little money it's ridiculous.
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Old 2nd February 2009 | Show parent
  #20
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Quote:
Originally Posted by Henchman View Post
Because this is simply the way it is with low-budget movies and TV shows.
And underexposed shots ARE being accepted now. People are shooting with malfunctioning cameras, and trying to fix it in Video-Post, because they were too cheap to budget the show properly in the first place.

I swear, some of the reality TV shows I've worked on have better sound and picture than TV Drama shows they are trying to do for such little money it's ridiculous.
In docs we don't ask these questions because we already know the answer--this was the best they could do under the circumstances. Next.

Philip Perkins
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Old 11th February 2009 | Show parent
  #21
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Jfriah's Avatar
 

Quote:
Originally Posted by bizzle View Post
Waves X-Crackle usually works great for distorted production. I have had only occasional success with the iZ de-clipper.
Shhhh! That's my job security!


I concur, I've had moderate succes (depends on length/frequency of the clips) with iZo. I usually resort to X-Crackle for a lot of DIA stuff--- there's always one character in a TV series I do that has a few lines per episode that need hitting 2-3 times. There's a loss of high-end but you deal...
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Old 11th February 2009 | Show parent
  #22
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Jfriah's Avatar
 

Quote:
Originally Posted by smurfyou View Post
Because they're more willing to pay for catering than audio? (no offense to catering, its not their fault)
Oh gosh and golly, I'm gonna have a whole slew of new t-shirt slogans thanks to gearslutz.com!!!

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Old 27th March 2009 | Show parent
  #23
Gear Maniac
 
josh broome's Avatar
 

Anyone try using the pencil tool in PT? One time I had to clean up some clipping, and x-crackle and x-click weren't enough, so I drew it in. It only worked on one clipped part in particular, but it worked very well.
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Old 28th March 2009 | Show parent
  #24
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Jfriah's Avatar
 

Quote:
Originally Posted by bizzle View Post
Waves X-Crackle usually works great for distorted production.

X-Crackle has been my 'job security' as the guy who can clean a good amount of stuff up. X-Crackle worked HUUUUUUGE on an MOW a number of years ago in the early days of HD video where there were all kinds of distortions and buzzes in the audio tracks from the camera and monitor system.

Saved an entire scene from ADR. It was a nice constant and most of the scene was a master, so the noise was continuous and went away quite nicely.

I haven't had the best of luck with any "x-clip" type plugs. I suppose I lose patience, knowing I can "usually" cut out the clipped piece if short enough/ALT it, and cut/shift/timestretch the remaining chunk and move along.


...and the pencil tool is your friend... I prefer to use the 'random' setting. Bit of an art form getting consistent results with the pencil but start trying it out. Myself, I draw a lot of stuff out and usually do "squiggly" drawing as opposed to just a smooth line, etc. I try to follow the curve but make it 'look' like the original without the clip or tick. If that helps any---

-Jeff
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Old 3rd April 2009 | Show parent
  #25
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kk@jamsync.com's Avatar
 

Quote:
Originally Posted by Alexey Lukin View Post
Here is one before/after declipping sample that I've done with RX recently: 2 links after the images.
Nice work!
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