Manual keyframing or Compressor filter? at DVinfo.net

Gene Brockhoff · April 29th, 2005, 11:42 PM

What are the pros and cons of using a compressor filter in FCP to limit audio spikes? I have been keyframing to keep them down for broadcast (between -6and-4db) but it's getting tedious and I just heard about using this filter but I'm sure there is a drawback right?

Glenn Chan · April 30th, 2005, 01:29 AM

I would definitely not try to keyframe everything. As you said it's very tedious... and a compressor can help you out a lot.

2- Which version of Final Cut are you using? This is a key piece of information. The older versions kinda suck audio-wise... but you can put the audio into Peak (which is on the FCP CD).
FCP4 is decent.

Ideally:
Add a compressor filter with a soft knee/curve at the top. Typically these filters show you a picture and it will have a curve instead of an angle. They may be called dynamics instead of compressor.
The soft knee sounds better. If you can't hear the difference it doesn't make a big difference though. At gentle amounts of compression it's not a big deal the quality of the compressor you use.

To hear too much compression, push the ratio to 6:1 or higher, push the threshold really far down (i.e. -30dB), and push make-up gain up 20dB or so.

Mess around with all these settings:
Use a gentle ratio like 2:1 ~ 3:1
Threshold something like -12dB
Attack and release something like... around 50ms ish. (This is a really rough figure)
Make-up gain like 2dB
(Sorry these numbers are going to be a little off)

If you want to make the sound really loud while staying broadcast legal, then a higher quality compressor can help you do that... but from your post, it doesn't sound like you'd need one.

A good article on compression:
http://www.dv.com/dv_login.jhtml;jse...questid=180977
registration required.

Gene Brockhoff · May 1st, 2005, 10:53 AM

Thanks so much for your well thought response Glenn. I have FCPHD. I guess Peak is around my hard drive somewhere though I havn't used it. I'll try your advice and post back. Thanks.

April 29th, 2005, 11:42 PM	#1
Gene Brockhoff Regular Crew Join Date: Aug 2003 Location: Oakland CA Posts: 46	Manual keyframing or Compressor filter? What are the pros and cons of using a compressor filter in FCP to limit audio spikes? I have been keyframing to keep them down for broadcast (between -6and-4db) but it's getting tedious and I just heard about using this filter but I'm sure there is a drawback right? __________________ "We are basically free, but who we think we are is not" Ram Dass

May 1st, 2005, 10:53 AM	#3
Gene Brockhoff Regular Crew Join Date: Aug 2003 Location: Oakland CA Posts: 46	Thanks so much for your well thought response Glenn. I have FCPHD. I guess Peak is around my hard drive somewhere though I havn't used it. I'll try your advice and post back. Thanks. __________________ "We are basically free, but who we think we are is not" Ram Dass

April 30th, 2005, 01:29 AM	#2
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	I would definitely not try to keyframe everything. As you said it's very tedious... and a compressor can help you out a lot. 2- Which version of Final Cut are you using? This is a key piece of information. The older versions kinda suck audio-wise... but you can put the audio into Peak (which is on the FCP CD). FCP4 is decent. Ideally: Add a compressor filter with a soft knee/curve at the top. Typically these filters show you a picture and it will have a curve instead of an angle. They may be called dynamics instead of compressor. The soft knee sounds better. If you can't hear the difference it doesn't make a big difference though. At gentle amounts of compression it's not a big deal the quality of the compressor you use. To hear too much compression, push the ratio to 6:1 or higher, push the threshold really far down (i.e. -30dB), and push make-up gain up 20dB or so. Mess around with all these settings: Use a gentle ratio like 2:1 ~ 3:1 Threshold something like -12dB Attack and release something like... around 50ms ish. (This is a really rough figure) Make-up gain like 2dB (Sorry these numbers are going to be a little off) If you want to make the sound really loud while staying broadcast legal, then a higher quality compressor can help you do that... but from your post, it doesn't sound like you'd need one. A good article on compression: http://www.dv.com/dv_login.jhtml;jse...questid=180977 registration required.