Subject:Graphic Dynamics causes pops?

Posted by: pbeshuk

Date:3/13/2004 12:03:31 PM

I'm using Graphic Dynamics with the following settings:
Attack = Release = 0.0
Threshold = -10.8db
Ratio = 5.5:1
Output Gain = 0.0db
Sync Stereo Gain is checked
Auto Gain is not checked

After the processing is done, there are noticable static-like pops introduced. I have a sample wave file which proves this. If I could get an address and a name, I'll send it on CD to someone at Sony if they want to hear it. Else, I'd appreciate any advice.

Subject:RE: Graphic Dynamics causes pops?

Reply by: MJhig

Date:3/13/2004 2:15:43 PM

>>>>Attack = Release = 0.0<<<<

Huh?

MJ

Subject:RE: Graphic Dynamics causes pops?

Reply by: rraud

Date:3/13/2004 5:13:09 PM

Not to repeat MJ but,
>>>>Attack = Release = 0.0<<<<
Huh?
>>>>Attack = Release = 0.0<<<<
Huh?
hint?

Subject:RE: Graphic Dynamics causes pops?

Reply by: pbeshuk

Date:3/15/2004 9:11:10 AM

I was trying to use Graphic Dynamics as a limiter.

Subject:RE: Graphic Dynamics causes pops?

Reply by: MJhig

Date:3/15/2004 6:27:16 PM

Then you would want to use a very high compression ratio like infinite.

The attack may be alright at 0 but you would want a long release say 500 ms to maybe even as much as 5000 ms.

But why bother, use Wave Hammer's limiter page only and adjust the threshold accordingly and maybe set the output to something like -0.3.

The clicks you are experiencing are probably caused by the compressor instantly attacking and instantly releasing.

MJ

Subject:RE: Graphic Dynamics causes pops?

Reply by: pbeshuk

Date:3/18/2004 6:56:24 AM

But what if I want to "chop the tops off" of some high, quick spikes in the waveform? Wouldn't the long release time reduce a lot more of waveform than that?

Subject:RE: Graphic Dynamics causes pops?

Reply by: MJhig

Date:3/18/2004 7:21:47 AM

That's where the Threshold setting comes in to play. The Threshold determines at what dB the audio is affected.

Example: Threshold is set to -10, the compressor will NOT effect anything below that threshold (-10)

MJ

Subject:RE: Graphic Dynamics causes pops?

Reply by: pbeshuk

Date:3/18/2004 7:37:59 AM

thanks.

Subject:RE: Graphic Dynamics causes pops?

Reply by: Rednroll

Date:3/18/2004 9:05:14 AM

"Example: Threshold is set to -10, the compressor will NOT effect anything below that threshold (-10)"

Not exactly correct MJ. Here's some information I posted from another thread on the adjustments for a compressor. I do agree that the release time is incorrect and part of the problem. Almost ALWAYS the release time is greater than the attack time, that's basic compressor 101 knowledge.

Compressor- It is named a "compressor" because it's function is to "compress" the dynamics range. That is, it will bring the louder parts of the audio closer in level to the quiet parts. It does this by turning down the volume of the louder parts, while leaving the quieter parts at their current level.

CONTROLS-
1. THRESHOLD: This is the setting that determines at what level the compressor will start to work. Anything below this level will go unaffected by the compressor, except during the release time duration after the threshold has been exceeded.

2. COMPRESSION RATIO: This is the amount of dB the compressor will turn down the audio depending on how much louder the actual audio is over the Threshold. Example. If you have a 4:1 compression ratio. The actual audio level must go 4 dB above the set threshold for 1 dB of gain past the threshold to occur. So what use to be 4dB past the threshold value, now get's compressed into 1dB above the threshold. If the audio exceeded the threshold by 10dB, it would now exceed it by 2.5dB. What use to be 10dB of dynamics get's comressed into 2.5dB of dynamics.

3. ATTACK TIME: This is the reaction time for the compressor to start working (ie start turning the volume down) once the THRESHOLD has been exceeded. Example: Attack Time=10mS. With this setting the audio exceeds the threshold value, but this level get's unaffected by the compressor until 10 milliseconds later, where at which point it will then start to turn the volume down.

4. RELEASE TIME: This is the time the compressor stops turning down the level once the audio level goes below the threshold value. EXAMPLE: Release Time=100 mS. The Threshold has been exceeded and starts to turn down the level of the audio after the initial attack time setting. The input audio then goes below the threshold value, the compressor will still turn down the audio so that dynamics are maintained for the next 100mS. After the threshold has remained below the threshold for 100mS, then the compressor will stop turning down the level.

5. GAIN: This is the level you adjust to bring the level back up once it's been processed by the above compression settings. EXAMPLE: If the "compression reduction" meter the majority of the time is reading "-6dB", then you might want to raise the GAIN to +6dB to bring the output back up to compensate for the reduction done by the compression. This brings the peaks that where turned down during the compression back to where they originally where. Therefore, what the compressor did was reduce the level of the loud parts, making them closer in level to the quieter parts, then you boasted the overall gain back up making the recording louder in level, thus the quieter parts are now louder.

AUTOGAIN COMPENSATION: Automatically increases the GAIN, taking into consideration the gain reduction amount.

Subject:RE: Graphic Dynamics causes pops?

Reply by: MJhig

Date:3/18/2004 2:28:10 PM

Red, I saw when you posted this the first time and thought it was and excellent presentation of compressor functionality.

I am confused however, are you saying that compression will continue on the audio even if the level drops below the threshold for the duration of the release? I've not seen anything, or it didn't soak in, that states this. Do you have a link? If this is the case I've learned something. It would seem this scenario would defeat the purpose of leveling the dynamics though.

If the compressor continued to compress the subsequent lower than threshold audio per release time it would have the opposite affect or raising the lower levels by virtue of squashing levels above the threshold (gain consideration asside) audio.

My understanding is that compressing occurs on levels above the threshold for the duration of the release setting "or" the level drops below the threshold.

MJ

Subject:RE: Graphic Dynamics causes pops?

Reply by: Rednroll

Date:3/18/2004 3:09:59 PM

Actually, I don't have a link to refer you too, this is just some of the common knowledge stored away in the rednroll grey cell archives. I do have a pretty easy way to prove this too you using Sound Forge.

Using simple synthesis, create a 60 Hz at 0dB mono sinewave. Have the timeline set too "Time". Select the duration of one of the cycles of the sinewave from -6dB to -Inf or (ie zero crossing.) Goto Tools>Statistics. Statistics will show you that the Max sample value is "-6dB". Now look in the far lower right hand corner of the wave view and this gives you the duration of your selection. This should be .001 seconds or 1mS. Now create a region in the region list or use the "Set" buttons, so you can easily go back to this selection of the waveform. Add a compressor in the plugin chain. Set the Attack=0mS, the release to anything greater than 2 mS (I used 20mS), Set the Threshold on the compressor to -6dB, and set the compression ratio to 6:1. I used Ultrafunks Compressor R3, because it has a nice envelope interface. Select the entire wave file and now apply the compression. Click on the Region to bring back your original selection. Goto Tools>Statistics....You'll find the Max Sample Value, now at -12dB. So that entire selection that you selected was below the threshold value, but it got reduced by 6dB (ie 6:1 compression ratio). That's because that duration fell within the release time. So according to your thought it should have remained at the same level if it was below the threshold. Get it?

Now how about this? Do the same thing and set your release time to 0mS. You'll now see some nice clicks on that sinewave instead of the natural looking sinewave, just like the original poster was complaining about.

Subject:RE: Graphic Dynamics causes pops?

Reply by: MJhig

Date:3/21/2004 11:28:48 AM

Hmmm, Red, very interesting. I see the results.

It's spring break time here in FL so it's been party time, still beer:thirty if you get my drift. Not good for math right now but I'm interested in how this behaves during the release. It must be variable I'm thinking (or am I?).

I'm going to look deeper into how this is working when I get time.

MJ

Subject:RE: Graphic Dynamics causes pops?

Reply by: Rednroll

Date:3/21/2004 1:15:33 PM

Not variable, just as I mentioned it reacted.

"The input audio then goes below the threshold value, the compressor will still turn down the audio so that dynamics are maintained for the next 100mS (ie the duration of the release time). After the threshold has remained below the threshold for 100mS, then the compressor will stop turning down the level.

So the compressor will continue to work for the duration of the release time, after the audio signal goes below the threshold. This is to maintain the dynamics so that the signal does not sound unnatural, and you can hear the compressor turning on and off too rapidly. Oh course if you want to hear the compressor pumping and turning on and off then you decrease the release time.

Subject:RE: Graphic Dynamics causes pops?

Reply by: jorgensen

Date:3/22/2004 11:51:13 AM

Attack and Release times are not hold times, but integration times

Basically this means it is the time it will take the output level to reach the new level.

In the analog world, a simple form of integration normally was used.
For attack time, a burst signal of 6dB to 12dB above the threshold should lower the signal, corresponding to the ratio setting, at the chosen attach time.
For release time, the output level should equal the input after the chosen period, and the threshold has been exceeded.

In the digital world, it is much more complicated, as most compressors use look-a-head, meaning the attack can take effect before the threshold is reached – and hold times could easily be implemented.

We still have to see digital compressors, where we can control all these new settings.