R/E/P Community

R/E/P => Recording - Engineering & Production => Topic started by: pgisclair on November 13, 2011, 09:48:11 am

Title: Why are the the bottom halves of my audio file bigger than the top half?
Post by: pgisclair on November 13, 2011, 09:48:11 am
I've searched here and on Goggle, and I can't find an answer as to why both of the bottom halves of the left and right channels of my stereo interleaved file are larger than the top halves.  I completed my PT mix, bounced to a stereo interleaved file and that's the first thing that caught my eye.  My first thought was that maybe I had phasing issues, but I checked and it looks correct.
Everything sounds good, so I'm not all that worried, but this just looks weird.  I'd like to know what I'm doing to cause this.  Any help would be appreciated.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Tim Halligan on November 13, 2011, 11:02:25 am
Everything sounds good, so I'm not all that worried, but this just looks weird.  I'd like to know what I'm doing to cause this. 

You're "mixing with your eyes".



Any help would be appreciated.

Sure.

Stop doing that.

You're welcome.

 ;D

Cheers,
Tim
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Rick Sutton on November 13, 2011, 12:55:48 pm
Any horns in the track?
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: pgisclair on November 13, 2011, 02:02:41 pm
No horns.  All acoustic mic'd drums, mic'd guitar amps and DI bass.  No Vocals yet.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Patrick Tracy on November 17, 2011, 02:04:49 pm
Many instruments have asymmetrical waveforms. Sometimes it's due to the transients being so short that the second half of the cycle is much lower (e.g. snare, slap bass). Other times it can be from distorted guitar amps with asymmetrical clipping. Those sounds are probably okay.

If the waves are not particularly asymmetrical but are not centered on the line you have what's known as DC offset, which is a bad thing.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: MarcAlanGoodman on December 06, 2011, 03:30:33 pm
I've searched here and on Goggle, and I can't find an answer as to why both of the bottom halves of the left and right channels of my stereo interleaved file are larger than the top halves.  I completed my PT mix, bounced to a stereo interleaved file and that's the first thing that caught my eye.  My first thought was that maybe I had phasing issues, but I checked and it looks correct.

Is this on every mix you do, or just a particular one? Could you post a screen shot for us?

The rule is if it sounds fine it is fine, but if it's due to DC offset you may be losing quite a bit of potential headroom.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Grant Ransom on December 23, 2011, 10:04:13 am
The rule is if it sounds fine it is fine, but if it's due to DC offset you may be losing quite a bit of potential headroom.

If you're using tape or a 16 bit system.
If it os a DC offset and not an asymmetrical waveform, it's worth removing though.
A Hi-Pass filter or OTB summing through Transformers would do it incidentally.

BTW, I just joined, and it's asking me to use captcha varification just to post. It's not going to do that every post is it? That might be a deal-breaker. :-(

Edit: Oh man, just tested it with an edit, and I have to squint at those damned pictures again...
And I got "You already submitted this post! You might have accidentally double clicked or tried to refresh the page."
Is this all going to be fixed or is it a "probationary" measure or is this just the way it works for everyone?
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Fletcher on December 23, 2011, 11:04:38 am
I'll forward these issues to the cyber powers that be... hopefully they will be taken care of in short order.  I have never seen that sort of thing when I was posting or it would have been taken care of WAYYYYYYY long ago.

Peace
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Fletcher on December 23, 2011, 03:00:04 pm
From webmaster Ernie:

The configuration is set to require two posts with CAPTCHA before
one is able to post freely without being prompted for the CAPTCHA. This is a security
measure to help reduce spamming in the boards.


So - the good news is - after post #2 all will be fine.

Just so you're in the loop as to why this security precaution was put in place... for a few months we were getting hit by some Russian "spammers" - like 250+ bogus "registrations" and posts a day... it was hell for the moderation / administration staff.  Sorry for any inconvenience this may cause... but if you went through what I went through during that period you'd appreciate some level of "spam deterrent"!!

Peace
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Grant Ransom on December 23, 2011, 06:08:15 pm
OK, Thank you Fletcher and Ernie for taking the time to explain...

Hope you and everyone here has a great holiday.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Ward Pike on April 24, 2012, 02:21:56 pm
I've searched here and on Goggle, and I can't find an answer as to why both of the bottom halves of the left and right channels of my stereo interleaved file are larger than the top halves.  I completed my PT mix, bounced to a stereo interleaved file and that's the first thing that caught my eye.  My first thought was that maybe I had phasing issues, but I checked and it looks correct.
Everything sounds good, so I'm not all that worried, but this just looks weird.  I'd like to know what I'm doing to cause this.  Any help would be appreciated.

Have you checked the phase of everything in your project?
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Patrick Tracy on May 08, 2012, 05:43:17 pm
Have you checked the phase of everything in your project?

How would phase (or polarity if that's what you mean) relate to an asymmetric waveform?
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: PRobb on May 08, 2012, 08:25:30 pm
I've often noticed this with brass, particularly trombone. I'm sure it's not DC offset and I get that it's not a problem, but I am curious how it happens.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Fletcher on May 09, 2012, 05:33:32 pm
I don't know if the DAW graphics are recording actual wave forms or not... but most music contains lots of asymmetrical wave forms.

If you have access to an oscilloscope, hook up a mic and a pre and sing a single note into it [hold it as long as you can] and look at the wave form.  Even on a single note the wave will be asymmetrical.

Peace
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: PRobb on May 09, 2012, 08:45:59 pm
Yeah- but with trombones I'm talking about waveforms that are 75% below the line.
Title: Re: Why are the the bottom halves of my audio file bigger than the top half?
Post by: Fletcher on May 10, 2012, 12:16:45 pm
Flip the polarity on the mic-pre and I'll bet they'll be 75% above the line next time... not Gospel - more of a guess really... interesting to hear if it works.