Dumb question about sound

ThatJimGuy schrieb am 08.08.2005 um 22:05 Uhr
Some of my source material has a low volume. I want to make all my project output files (MPG) the same volume, very similar to making the sound volume consistent when converting a CD to MP3. The sound software I use for audio allows me to "normalize" the sound as a percentage (I usually use 90%, some people I know use 100%). However, in Vegas, it *seems* to only allow adjusting the Db up or down for the track(s).

I admit I'm not sure where my sound software gets the % from, but it seems difficult to get the right and consistend volume in Vegas.

Save any replies which amplify my stupidity please ;-)

Kommentare

John_Cline schrieb am 08.08.2005 um 22:09 Uhr
A lot of people will use the "Normalize" function in Vegas. This will adjust the peak level to a certain value. Unfortunately, peak levels are meaningless when it comes to determining how "loud" your final product is. The human ear doesn't determine loudness by the peak level, it determines it by the average (or RMS) level. The "normalize" function in Vegas is useless because it only makes adjustments based on peak levels and that's not the way we hear things.

If you're watching a movie on TV and it has some relatively quiet dialog and then a commercial comes on, the commercial sounds louder because it has been heavily compressed in order to raise its average level (and get your attention.) The fact of the matter is that the movie and the commercial probably had the same peak level, it just that the commercial has a much higher average level.

Audio compression and limiting is an art form and it takes a lot of experience to do it "correctly." There are no hard and fast rules to determine the appropriate average level, you'll just have to play it by ear. But like I said, peak levels are virtually meaningless (well, as long as they don't exceed 0db.)

You could use the Normalize function in Sound Forge, it can be set to normalize for average levels, which is what you want. Render out the audio from the entire timeline and pull it into Sound Forge, then mark each different clip or section that needs to be level matched. Use the Normalize function in Sound Forge and set it to normalize using "Average RMS power" and normalize to -20db and select "If clipping occurs apply Dynamic Compression." -20db is a good starting point, you will have to play with this value for your project. Once you have determined the appropriate RMS level, use that same value for everything and the loudness of will be matched throughout your entire project.

John
ThatJimGuy schrieb am 01.09.2005 um 06:24 Uhr
Thanks John. What I do now (a bit slow, but it works) is I render the project as a .wav file and bring it up in my sound editor that I use for converting LP's, cassettes and Cd's to MP's and use their normalize function. Then I just sub the result file for the main sound track in Vegas.

It just seems a bit strange that I can see on the waveform that it is a low "volume" soundtrack, but I could spend more time trying to fiddle with the Db+ on it and only have a small visual indicator of how "loud" the sound is. Also, I don't want it to clip.

PS I hate that loud commercial stuff. I used to have a Magnavox TV with "smart sound" that would keep the sound at the same level, no matter what. I don't know if they still make them, though. And I'm not buying another TV until the digital/HD/whatever standards become mandatory. OK I lied, I want a wide-screen plasma the size of a football field, but unless all y'all want to make donations, that won't happen ;-)

Thanks again.

- jim the eternal newbie
Edin1 schrieb am 01.09.2005 um 07:29 Uhr
What John is refering to as "average level" is actually called loudness, and the "Normalize" function in most audio editors and CD rippers usually sets what is commonly refered to as "Peak level".

Normalizing peak level simply adjusts the volume of your whole audio file in order to bring its maximum value up to the specified value. In digital audio, all the sample values are defined, and if the volume goes above the maximum value possible, it simply gets "cut off", where anything above it remains at that same maximum level (this is called saturation), leaving a straight line (making it a DC or 0Hz, which, if lasted longer would produce no sound, as sound is defined as a wave, 20Hz to 20kHz for humans), and causing an audible distortion, which sounds pretty much like an amplifier with volume turned all the way up, and the audio sounds "broken".
Normalizing peak level maximizes your volume up to a point where its highest sample value doesn't exceed 100% (highest sample value possible), or anything less than that, which you can set (I use -0.2dB peak level, or about 98%). With digital audio, you want to use the maximum dynamic range available without changing anything else in the original sound, and normalizing peak level does that, especially for audio files with low peaks.
That's all there is to it!

Normalizing using average RMS level or loudness sets the apparent loudness of your audio file to a value that you specify. It raises the quieter parts of the sound file, in order to achieve the specified average RMS level or loudness.
It only cares about peak level when a portion of the sound exceeds it, and in such case it applies dynamic compression, which supresses that portion to be below the peak level.

While normalizing peak level simply changes the volume of your whole file, without changing anything else, normalizing loudness changes both the volume of an audio file and portions of it in regards to other portions of it, which changes the essence of that audio file. If you had a recording where violins were supposed to be quieter than, say, piano, forget it! The violins' loudness will now be closer to piano's loudness, if not the same. That's what average RMS level or loudness normalization does.

My suggestion for you is to first normalize your peak levels, and then adjust volume in Vegas, reducing it for louder tracks, and keeping it equal to or less than 0dB for quieter tracks, or maybe raising their volume level if necessary, but make sure your Master Volume level doesn't peak above 0dB, and always keep it below 0dB!
Use RMS normalization only when you have to!
farss schrieb am 01.09.2005 um 07:45 Uhr
There's a number of presets in the track compressor that comes with Vegas, you will not go to far wrong with them. I'm not saying you cannot do better with more tweaking but they're better than nothing.
Thing is if your levels are all over the place then unless you have a compressor with smart threshold it's going to do nothing for you, if your levels are not hitting the threshold then it'll do you no good.
As a real basic way to handle things, normalise all your clips and use the "1.5:1 compression starting at -24dB" template.
Don't be afraid to experiment and watch what the meters in the compressor FX are doing, you'll start to pickup the idea.
Before all the purists jump all over me, this is only a basic way to work, just something that will not produce any ugly results.
My best advice to anyone is you can read and study all you want but it's only be experimenting that you'll get a feel for how YOUR material reacts and how it suits YOUR audience. Remember a good sountrack takes into account where it'll be heard, that's one of the best tips I picked up from a master of the art. Also remember Vegas is non destructive, keep saving different versions if you like, but you can always start again from scratch.
Bob.
rs170a schrieb am 01.09.2005 um 10:09 Uhr
DSE wrote an article called Audio Mastering in Vegas Video that may shed some light on this for oyu.

Mike