Reaching for the expander

vitalforces wrote on 2/22/2005, 11:42 AM
I'm a writer/director/editor trying to take on sound mastering in a DV film project being sent off to festivals before hiring a post audio expert--we're meeting some deadlines with a 'rough cut' but want it to sound as good as my limited ability can take it, for a first impression.

The problem is: When normalizing a dialog track, all the ambient background sound is amplified as well (of course). I've used EQ, compression and noise reduction on the track but it's a little like the monkey-with-a-typewriter analogy. I'm using the plug-ins but I'm not convinced I'm using them the most effectively. By now I understand that I can go back and fine tune the EQ better to minimize things like a boomy room and a voice that's too bassy.

The remaining issue that intrigues me is using a downward expander instead of a noise gate, "in between" the spoken lines of dialog, because of course you don't want a complete dropoff to silence as each character speaks a line--rather, a reduction to a very low noise level.

I just recenly got my head around how an expander works, thanks to an internet tutorial. Sorry about the long lead-in to the question here, but: Would anyone have a moment to comment on what's the best tool, or tool combination, to achieve what I'm after? Graphic dynamics? A special setting for noise gate? I have Vegas 5 and SF7.
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Comments

farss wrote on 2/22/2005, 11:59 AM
Over on the audio forum the guys were playing around with a plugin that'd write an automation envelope based on the VU of a track. You could then use that envelope to control well, gain or Eq. But the best thing would be an decent noise gate ( the one that ships with Vegas is near useless from what I can see). What a decent noise gate needs is a bandpass filter in front of it. Actually what we need are three teminal FXs. I've yet to see anything that advanced on any DAW yet it was pretty common back in the days of analogue.
What they let you do is have a gate that is driven by an FX that isn't in the chain. So you can take the signal from the track, feed it through say a notch filter and use the output of that to control the the gate without affecting what's going through the gate. Result is that say only audio in a 1 octave band can turn the gate on but when it's on it passes the full band.
Other uses for this include having the level of one track control the Eq on another track, makes many tasks automatic.
Bob.
Former user wrote on 2/22/2005, 12:56 PM
Some WAV editors have a noise reduction function that might help.

You sample a "silent" part of the audio track, and then it will try to filter that out throughout the track. It can be used very effectively. I know Cool Edit and I think Goldwave have this function.

Dave T2
filmy wrote on 2/22/2005, 1:17 PM
>>>Over on the audio forum the guys were playing around with a plugin that'd write an automation envelope based on the VU of a track<<<

That is a free plug-in by the way. The "pro" verison costs - find out more about Digital Peak Meter. And by the way the link they have to the Vegas tutorial is dead - the link works but the link to the actual video from the link is dead.

But to the question - dialog editing is an art in itself. You can not just drop some magic filter onto the track and make it all better. Yes, you will increase all backgroud noise by increasing volume so typically what you would do is cut a dialog track as well as a production track that contains everything else but the dialog that was captured during production. This will also help to smooth out changes from shot to shot. Ideally the production sound mixer or location sound recordist has maintained levels from scene to scene. And very important - they have taken room tone at each location.

Best scenrio is that you do not have high BG noise, but if there is and you have no money to ADR the scene you have to work with what you have. You can EQ and use Noise reduction but this also will change the overall tone. So you could something else as well - cut the dialog - isolate it. You blend this in with the production track, Once you add in music and perhaps other hard effetcs you may find you never notice the BG noise changes. You can also add some light compression on the dialog track and than when you do the final mix use something like the Waves L1/L2/L3 maximizers on the overall track. Remember that volume can be percieved as being loud, even if it is not peaking. A quiet scene may be "loud", but yet everything is a whisper...it is hard to acheive this when on set the actors were really whispering and the location sound recordist pumped up everyhting in oder to get a peak reading on the whisper. Even harder is when you have freeway noise bleeding through the walls. On the other hand ADR has its own quirks as well.

Somewhere Spot did a very good little tut about mixing and it included some tips on noise reduction and dialog EQ-ing. Do a search - or look around on the Sundance site or over at DMN - it is around somewhere.

As for what I use - in the analog days of cutting film I really loved the BBE Sonic Maximizer. I still like it but when everything is digital you don't really have to brighten up dialog as much. I got the broadcast bundle from Waves and it is pretty awesome out of the box. The L1 maiximaizer I use alot - it will bring up overall volume but make it stay within the levels. It is also a percieved volume increase if you use it that way. Nose reduction is a nice thing to help cut down backgorund noise - the Sony one is nice, I lean towards the Waves one - but both are good. Waves MaxBass is good - the one included in the broadcast bundle allows you to dial in a set frequency so after all the EQing is done you can restore a bit of low end at a set frequency.
vitalforces wrote on 2/22/2005, 2:13 PM
Thanx gentlemen. I'll follow up on your various ideas.
Opampman wrote on 2/22/2005, 2:28 PM
Might I also suggest in addition to those in the other replies, a program called DC6 from Diamond Cut productions. While originally designed for removing noise from phonograph records (remember those) I find it works great removing noise of virtually any type, plus it has an incredible array of expander/compressors, noise gates, etc. and other noise removal tools. If you like, you can even "sweeten" the sound with a virtual 12AX7 vacuum tube and it allows you to import and play the video as an AVI file also. In fact, as much as I like Sound Forge, DC is set as my default audio editor in vegas. There is even a rather "pricey" version for forensic use to extract inaudible audio from noise.
vitalforces wrote on 2/24/2005, 2:09 PM
Just wanted to share with the forum, a plugin I found called FASoft Compressor 1.1. It has a graphic window which allows you to reshape various curves with a mouse, and create a custom filter. In my case I created what I wanted--a noise gate with a soft knee and band-pass feature where background noise between spoken lines of dialogue was lowered but not completely (unnaturally) silent. Knowing I'm speaking to people 95% of whom likely know more about all this than me, let me offer the link for this remarkable $20 plugin.

http://www.softpedia.com/get/Multimedia/Audio/Audio-Plugins/FASOFT-Compressor.shtml