auto leveler attn: happyfriar

Rednroll wrote on 9/23/2003, 10:06 AM

Happyfriar said:
3) an "auto" volume leveler: when you stack lots of audio on top of eachother, it's easy for there to be clipping. if I could tell vegas to automaticly create a volume envelope that will stop all cliping (or max at a certain db) this would help A LOT

I've seen you've post this request a couple times. There is a way to do this in Vegas. This is known as a "limiter" in the audio world. You can easily achieve this by using the Sonic Foundry "Track compressor". The only thing different between a compressor and a limiter is the compression ratio. That's why most hardware compressors you can buy will say "compressor/limiter". A limiter is usually defined with a compression ratio of 10:1 and above, and a compressor with anything lower than that.

Explaination of "compression ratio": The first part of using a compressor/limiter is to set the "Threshold" of where it starts to work at. This is the level of the audio where it will turn on at, anything lower than that level will go through the compressor/limiter without any processing. The next thing to do is to set the "compression ratio". If you set the compression ratio at 10:1, this means that the audio level must exceed the threshold by 10dB for there to be 1dB of gain above the threshold. Within the Sonic Foundry Track Compressor you will see a preset named "hard limiter". This preset actually has a compression ratio of "Infinite:1" and the threshold is set at -6dB. This means once the audio level reaches the -6dB point there will be no gain added above -6dB. For what you are looking for, it would be good to use this preset and then adjust the threshold to something just under 0dB, and this will assure that no clipping happens. You could use this FX on the tracks and busses.

For your volume envelope, just use the automation of the Track Compressor and the envelope created for the threshold.

With a use of a limiter, it also makes me wonder why some users feel the need to have track meters. To me this is a big waste of CPU power and screen space. If you are really concerned that your track levels are exceeding the 0dB distortion point, then just put a limiter in that track.

Hope this helps,
red

Comments

RichMacDonald wrote on 9/23/2003, 10:24 AM

>With a use of a limiter, it also makes me wonder why some users feel the need to have track meters. To me this is a big waste of CPU power and screen space. If you are really concerned that your track levels are exceeding the 0dB distortion point, then just put a limiter in that track.

Reason 1) A limiter changes the sound, something you might not want. (e.g., over-loud TV commercials).

Reason 2) The SF limiter is not infallible. Even with the compression ratio at infinity and the attack at minimum, It does not react immediately. Clearly it does not "look ahead" as a software limiter could. Thus, you could add a limiter and *still* get clipping.

Chienworks wrote on 9/23/2003, 4:17 PM

I think a nice feature would be the ability to have Vegas do a quick scan through the project and find the maximum audio peak, determine if it's above 0dB and by how much, and then automatically crank all the track level sliders down by that much plus maybe another half dB. That would fix the overdriving problem without modifying the mix.

Rednroll wrote on 9/23/2003, 5:54 PM

Reason 1) A limiter changes the sound, something you might not want. (e.g., over-loud TV commercials).

Good point, but that's the reason for the high threshold, if someone is really mixing that far over 0dB peak.....well, ahhh you might need to go back to mixing school because changing the sound should be the least of your worries. :-)

Reason 2) The SF limiter is not infallible. Even with the compression ratio at infinity and the attack at minimum, It does not react immediately. Clearly it does not "look ahead" as a software limiter could. Thus, you could add a limiter and *still* get clipping.

I agree, although they do have a "0 mS" attack setting, I believe you're correct that it really isn't 0mS. I also did a little test with the limiter placed in the master out and I was able to go over 0dB even with the threshold set as low as -1dB, and raising the level of the track fader, which means their Inf:1 setting isn't really inf:1 either.

Another thing I remembered after making this post is that the track inserts are pre-fader which means a limiter wouldn't work as I described for the track insert anyway if you raised the volume of the track fader too high.

Ok, ignore my original post, I thought I had a usuable work around, but after I experimented around a little more with it I verified that the SF track compressor is fallible as you stated, and the settings are not quite as accurate as I had believed them to be. Well, back to the lab again. :-)

This, did make me think of another feature suggestion....pre and post fader track inserts...along with a DX meters...hmmmm ok.

TheHappyFriar wrote on 9/23/2003, 11:31 PM

Thanks for trying to help. I never knew what the track compressor was for before now, so you tought me somrthing new! Just last night I started using the EQ plugin for some basic noise reduction.

I'll look into using the compressor for what i need. I've just started getting clipping a lot because of placing songs i made in acid on the track with some voice and sfx, causing it to peak. I installed the Audio SDK so i could try (key word here!) to make some directx plugins. So, maybe i could come up with something that would do the trick (doubtful, but worth a shot).

thanks again!