Avid Pro Audio Community

Avid Pro Audio Community

How to Join & Post  •  Community Terms of Use  •  Help Us Help You

Knowledge Base Search  •  Community Search  •  Learn & Support


Avid Home Page

Go Back   Avid Pro Audio Community > Pro Tools Post Production > Post - Surround - Video

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-07-2003, 04:39 PM
Syncman Syncman is offline
Member
 
Join Date: Nov 2003
Location: Detroit, Mi
Posts: 22
Default The -20 dB discussion

Okay, Here it is. Who can tell me why the hell we ended up with 20 dB of headroom. Because we can? Because Sony decided it was the way. Everytime I mix down and watch those top 6 dB just sit there unused (I use -18, sue me), I kind of laugh to myself about the state of things.

So what to do, not use the top few dB, the best sounding bits? Use -12 for reference in a blatant protest to the Sony way and confuse editors everywhere? Or the most popular way, compress the hell out of the mix so it seems as though it's all the way up there (kidding). Really how do you all handle it? I'm assuming most just throw them away and leave the levels down where the kid bumping it to 1/2" will stay out of trouble, but is it right?

Chip

Reply With Quote
  #2  
Old 11-07-2003, 05:41 PM
trakbytes trakbytes is offline
Member
 
Join Date: Dec 1969
Location: Los Angeles CA USA
Posts: 845
Default Re: The -20 dB discussion

Turn down the monitors and print hotter!

Actually, I believe the -20 standard was arrived at as a means to get a full-level mag film mix onto 16 bit digital media without blowing it out. -24 was tried for awhile, but it was too low for average levels. I used to get a lot of ADR (still do, for that matter) where the waveform is barely visible. Signal to noise sounds like a cassette tape. A common myth is that digital has no noise, where in reality it is plenty noisy if recorded too low.

I see plenty of 5.1 mixes where every one of the bits is used. TV broadcast is a different story, as program material is limited to +12. Here, the top 8db remains unused. I have been told that this is a limitation with Digibeta machines, although I find that kind of hard to believe with today's technology. Maybe Dr Sound has some more concrete explanation?

rcm
__________________
Save early and often! (or once a day whether you need to or not...)
Reply With Quote
  #3  
Old 11-07-2003, 07:52 PM
Chief Technician's Avatar
Chief Technician Chief Technician is offline
Moderator
 
Join Date: Dec 2001
Location: NYC
Posts: 6,981
Default Re: The -20 dB discussion

Could you be more specific about the limitation? I can certainly hit the deck at 0dBFS (if the broadcaster's would let me, alas we don't do mixes for FOX that often).
__________________
Jonathan S. Abrams, CEA, CEV, CBNT
Apple Certified - Technical Coordinator (v10.5), Support Professional (v10.6 through v10.10)
Reply With Quote
  #4  
Old 11-08-2003, 12:39 AM
TVPostSound's Avatar
TVPostSound TVPostSound is offline
Member
 
Join Date: Aug 2002
Posts: 3,217
Default Re: The -20 dB discussion

Quote:
I have been told that this is a limitation with Digibeta machines
Not true, sattelite transponders have a HARD -8 limiter, anything above gets rejected, if it passes the QC, it gets distorted!!!!!
__________________
IMDB
Reply With Quote
  #5  
Old 11-08-2003, 07:03 AM
Soundwise Soundwise is offline
Member
 
Join Date: Dec 1969
Location: Helsinki, Finland
Posts: 21
Default Re: The -20 dB discussion

In Finland the TV broadcast level is -12dBfs for Digibeta masters. Peaks can go up to -3dBfs. Go figure.

Jari
__________________
Jari
Soundwise Ltd
Reply With Quote
  #6  
Old 11-08-2003, 01:17 PM
dr sound's Avatar
dr sound dr sound is offline
Member
 
Join Date: Jul 2002
Location: Burbank, CA
Posts: 2,118
Default Re: The -20 dB discussion

Why do we have to hit stuff at the absolute maximum to feel we've used every "good sounding bit"?
Thank God we have dynamics. Hell, if you wanta slam it go for it. Just don't bitch when it gets rejected or is lower in volume then the next show or spot. It takes skill to make it fit within the guidelines.Find out what they are and go for it. Otherewise have at it and keep on bitching! The reasons are as explained, satelites and other mediums are the reason for -20. I Like it!
Just a point of view,
__________________
Marti D. Humphrey CAS
aka dr.sound
www.thedubstage.com
IMDB http://www.imdb.com/name/nm0401937/
Like everything in life, there are no guarantees just opportunities.
Reply With Quote
  #7  
Old 11-08-2003, 06:38 PM
Chief Technician's Avatar
Chief Technician Chief Technician is offline
Moderator
 
Join Date: Dec 2001
Location: NYC
Posts: 6,981
Default Re: The -20 dB discussion

I never claimed I didn't like it. Perhaps I should've phrased it differently. We stay within specs, and FOX as I understand it wants you to hit at -2dBFS. So, when we mix for Discovery and they say -10dBFS is your peak ceiling, that's how we mix.
__________________
Jonathan S. Abrams, CEA, CEV, CBNT
Apple Certified - Technical Coordinator (v10.5), Support Professional (v10.6 through v10.10)
Reply With Quote
  #8  
Old 11-08-2003, 08:04 PM
TVPostSound's Avatar
TVPostSound TVPostSound is offline
Member
 
Join Date: Aug 2002
Posts: 3,217
Default Re: The -20 dB discussion

FOX is digital, so we get full dynamics.

I just printed a Dicovery/Travel Channel show the delivery specs are -12dBfs or +8 analog,
-20dBfs = 0Vu

But they want the average VU to be -5 to -2 at 300ms analog metering response (Can you say Dorrough?). That left me 10 to 13 dBs of dynamic range, not bad for a talkie with BI music!!! Its nice to mix with minimal compression!!!!
__________________
IMDB
Reply With Quote
  #9  
Old 11-09-2003, 08:26 AM
Richard Fairbanks Richard Fairbanks is offline
Member
 
Join Date: Dec 1969
Location: New York, NY
Posts: 1,861
Default Re: The -20 dB discussion

I appologize up front for the tone of this reply. Don't take it personally but this topic is worn out for me.

Hey, if you want to set your system for a reference level of -12 (instead of -18 or -20) then go right ahead. Just be sure you bring your final mix level back down to -20 before you make your deliveries. It is the networks who have set their delivery standards to be what they are, not a room full of misguided editors. Existing land and satelite distribution chains are filled with old technology and the built in limits exist until the equipment is replaced.

Personally, I prefer to do my final deliveries with 1:1 gain, which means my whole system is set for a -20 reference level. I prefer to have the extra headroom in my tracks for mistakes and surprises. I believe it is foolish to operate at tippy top peak because when your tracks are constantly hitting the top you will be forced to always pad your signal before you process further. Talk about a waste of time and resolution! You cannot even do subtractive eq because the eq will actually cause a bit of gain somewhere out of band. Gain applied to a 0dbfs peak equals distortion.

"Best sounding bits"???? There is a one bit difference between 0dbfs and -6dbfs. Technically you will probably get between 1 and 2 bits of extra resolution if you operate with no headroom. I did it that way in the old days and can honestly say the negative impact in terms of having no spare headroom was not worth it to me. I could honestly never hear a difference in sound quality. What I could hear was the increased noise floor when I had 48 tracks opened up and no signal in most of them. That was on digital 16 bit tape machines. Today we can mute those silent regions on our tracks, which effectively turns the track off and removes the noise. Or just mute the freakin' fader. We can work at 24 bits, which takes most of the weight out of your concerns. It is much more important, in my view, to concentrate on good mixes and good content, and forget about that extra bit just sitting there unused but available to catch you when you mess up.

But, hey, go ahead and do whatever makes you comfortable. After all, there are no rules and if you want to live on the edge of crazy then I think you should.
__________________
Call me by my real name, "Postman"
Reply With Quote
  #10  
Old 11-09-2003, 11:13 AM
dr sound's Avatar
dr sound dr sound is offline
Member
 
Join Date: Jul 2002
Location: Burbank, CA
Posts: 2,118
Default Re: The -20 dB discussion

Thanks Richard! Well said!
__________________
Marti D. Humphrey CAS
aka dr.sound
www.thedubstage.com
IMDB http://www.imdb.com/name/nm0401937/
Like everything in life, there are no guarantees just opportunities.
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Protools 8 New look, old look! Discussion Ale Pro Tools TDM Systems (Mac) 1098 07-07-2009 12:04 PM
Synchronic discussion? daeron80 General Discussion 12 04-06-2006 07:55 AM
Further X-Curve discussion Andy Hay Post - Surround - Video 12 05-22-2005 11:02 AM
Mix Discussion - Effects or Not Kevin Genus 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Win) 1 10-03-2002 11:51 AM
man, ive had another discussion with people about PC or MAC executive_chu 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Mac) 4 05-02-2001 11:27 PM


All times are GMT -7. The time now is 08:24 PM.


Powered by: vBulletin, Copyright ©2000 - 2008, Jelsoft Enterprises Limited. Forum Hosted By: URLJet.com