Understanding the Mixer Meter

[solarblast]

I'm considering a simple scenario. One video and one audio track. OK, I'm looking at the Master Mixer. It's graduated from 6 to 54 units. I take it these are relative measures in Db. 6 Db denoting a doubling, or (-) halving. Apparently, this is the overall volume control for all audio, correct? If I apply audio effects (NRT), audio envelopes, and audio fade-ins, then I would hear the result of them, correct?

Apparently, the game is to make sure the entire track does not produce periods of orange-ness at the top of the bar. As the track is played, numbers appear at the top and bottom. What do they indicate? Max, min values? I see -2.5 and -5.4 at the top, and 0.4 and 0.4 at the bottom. What do they mean. I would have guessed 0.4 and 0.4 means the L & R tracks are above some value. If so, then I would think the orange indicator would be at the bottom. The 0.4s stay pretty constant across the small segment I'm looking at, 2 minutes, Comments?

Since the top is showing negative values, wouldn't that indicate a diminished sound? However, it seems it gets louder as the bar's height increases. It makes sense to color the top of the bar orange as the bar height increases, and causes more distortion.

If I play with the slider, I can get positive values on both bop and bottom, and the same (top, bottom) for negative. It seems these values do not relate to the scale in the middle.

[solarblast]

BTW, this is really about the Vegas mixer. I guess in this Forum, other s/w packages that might be discussed here use some variant.

Perhaps this (red-orange, scales, Dbs, ...) is somehow so obvious it doesn't need a n explanation. However, here's some background from the web. It appears historically it's called VU U.S.) or PPM (British, European) meter.

From the Buzz Turner (Radio College) site:
The VU meter was designed to respond to sounds in the same way our brains perceive "loudness". The duration of a sound will affect our perception of how loud the sound is. A drum roll will sound louder than a single hit on a drum. Guess what? The VU will register higher on the drum roll. The bottom line is that a VU will work well on sounds of continuous duration but will not show rapid transient peaks.

And Wikipedia (VU Meters):
Tape and cassette decks typically used physical meters similar to needles on a compass. The needles would be "pegged" when they hit the physical pegs which stopped the maximum motion of the needle. The first high-fidelity deck, the Advent, used only one meter, which could be switched to average both channels, or either channel, but this was never adopted by any other design. When LEDs were developed, they were often used to indicate peak levels, and later arrays of them replaced mechanical meters, and later LCD and fluorescent displays which are not subject to Newton's laws of motion to limit reaction time. Computer recording software often emulates an array of LEDs. ... [more on the entry]

Continuing with Decibel from Wikipedia
Acoustics
Main article: Sound pressure
The decibel is commonly used in acoustics to quantify sound levels relative to some 0 dB reference. The reference level is typically set at the threshold of perception of an average human and there are common comparisons used to illustrate different levels of sound pressure.

A reason for using the decibel is that the ear is capable of detecting a very large range of sound pressures. The ratio of the sound pressure that causes permanent damage from short exposure to the limit that (undamaged) ears can hear is above a million. Because the power ...

Well, somehow it all never describes the Vegas scales and so on. I guess one just gets the "feel" and comfort from all the extras. Just keep it out of the red (orange) and note the doubling or halving of power ...

Technology gone wild (with the addition of "extras")?!

VU = volume unit
A reference for a bit of the technological ideas behind it http://www.shure.com/ProAudio/Products/us_pro_ea_vu