Shouldn't the Anna Vu meter correspond with the volume dB scale? With the overdrive part in "red" ? Maybe I have no idea what I'm talking about.

Calvin

Okay to clear up what the visual is actually displaying I'll tell you exactly what the needle deflection means.

Each needle represents each channel (left & right) - For mono MP3s the visualisation library is conned into thinking it has a stereo signal with the same data in each channel regardless of the current visual.

Each needle can deflect by a maximum of 90 degrees. At any point in time the actual deflection of a needle is the decay damped rms of the audio. That is to say that if the rms of the current frame exceeds the decay damped value from previous frames that rms value becomes the new decay damped value, if it does not then the previous decay damped value is used and then decayed by a constant amount.

According to Time's reference this means that the visual is correctly named as the rms signal is used. The decay damping (and lack of attack damping to some extent) can be regarded as the method used to digitally model an analogue VU meter.

Given that the samples used in generating the RMS value are 16 bit signed then the maximum possible rms value (based on a square wave) is 32767.

Because the positioning of 0db sets at what point the rms value is being measured relative to it is important that this point is meaningful. The convention in analogue electronics is to use the rms of the maximum possible sine wave to measure the signal relative to. Our signal is bounded by the square wave maximum so this would be a logical choice (to position 0db at the far right of the scale) - However it is would probably be more in keeping with the theme of an analogue vu meter to use the sine wave to position 0db.

Therefore the position of 0db should be:

(90 degrees divided by the square root of two)degrees from the left of the scale.

The square wave is 3db louder than the sine wave so that positions another point at the far right of the scale.

The far left of scale is -infinity decibels (subject to debate), it just remains to make the scale meaningful between 0db and -infinity db.

Hope all of this makes sense,
Toby.

(90 degrees divided by the square root of two)degrees from the left of the scale.

And this number is?

(Don't have a SQRT button on the Windows Calculator )

Don't have a SQRT button on the Windows Calculator

Tony, your forgetting to apply MS logic to the problem. Go to View, Standard, and there is your SQRT button on the right upper edge. No clue why the scientific one dosen't have it, then again I do only trust RPN calculators anyhow.

ROFL, okay.

Why duplicate functionality? Not that I believe that's the reason sqrt isn't there...

You do have a x^y button that will do sqrt if you give it 0.5 as second argument.

/Michael

Wait, that can't be right. That tells me that 0db should be about 63-64 degrees from the far left of the scale.

SQRT of 2 is 1.414...

90 divided by 1.414 is 63.649...

So that means 0db would be on the left third of the scale instead of towards the right.

I'm doing it wrong or not understanding something.

AFAIK start to end is 90 degrees, mid scale (straight up) is at 45 degrees...

/Michael

He said "from the far right end of the scale".

EDIT: I just re-read it. He said LEFT end of the scale. I am an idiot. All is well.

/me goes to work on the image.

Okay, the 0db marker was pretty close to that point. Just have to move it a couple pixels to the left and mess with it some more. Cool...

Okay, attached is my latest stab at an Anna VU visual replacement.

For those that wish to try it, upload it to the player as vuback.raw into /empeg/lib/visuals as instructed here.

The 0db point is about (as close as I could get it with low-rez pixels) at 64 degrees from the left end of the scale. The right end of the scale is labeled as +3, and the left end of the scale is numbered approximately what Tim suggested.

I think that it is not possible to get it perfectly accurate to the real world, and this is about as close as we're ever going to get it.

And this is what the latest one looks like on the screen:

Very Nice!

Thanks. Now the question is whether or not this meets Toby's criteria to use as the "official" Anna VU visual....

And thanks for the FAQ entry.... that was the first time I sent a file to the player and all went well! (I always get worried when mounting the music partition rw takes several minutes!)

The engineers here at work approve!

EDIT: 1 thing about the FAQ... it doesn't mention to change the Hyperterminal (assuming that is what people mostly use) to Zmodem. I believe (at least in my case - w. a 2 day old install of Win2k) it defaults to ZModem w. Recovery or something similar...

I always get worried when mounting the music partition rw takes several minutes

I think it was Mark Lord that pointed out that one can add the nocheck option to the mount command in the rwm script to speed it up.

You can change the /bin/rwm script to contain the following (the red stuff is the change).
==============
#!/bin/sh
mount -n -o remount,rw,nocheck /drive0
[ -e /proc/ide/hdb ] && mount -n -o remount,rw,nocheck /drive1
==============

If you edit the file on a non-Unix machine, use an editor that can save the file with unix style linefeeds. After (re)uploading, make sure the file is executable, default permissions seem to be 0755 (rwxr-xr-x)

/Michael

Very nice!

I especially like the lower left screw head being rotated...

I was gonna draw four completely different screw head angles, but got fed up.

Looks and works great!

Mmm.. I'd really prefer if the upper right screw were the same orientation as the lower left.. symmetry or something.

It's deliberately asymmetrical.

What's wrong with INV x^2 ?

Besides, *everybody* knows that 1/sqrt(2) ~ 0.707

I knew it was, that's why I mentioned it.

It's one of those subtle things, that I think most people wouldn't notice, kinda like those two thin horizontal lines on Trinitron monitors, only not as annoying.

I actually like it being rotated... I think it gives it more of a quirky, non-mainstream feel.

kinda like those two thin horizontal lines on Trinitron

they should put warnings on the box about those they are annoying

VERY ! cool... I love it, kudos, keep up the good woork

Dude, YOU ROCK!

Nice work Tony! It looks great!
Thanks!

Thanks!

Hey, Toby. Tim likes it. Does that mean it can be the default visual now?

A suggestion here - let alternative versions of a visual to be selected by using the "select mode" button on the remote, like when changing the visuals that sometimes leave trails. Then we can all choose the version we prefer, and the visual selection menus don't end up being any more massive than they are.

Interestingly, I have some audio test signals on my empeg.

When I play a -14db Sine wave reference, the numbers line up perfectly with the expected value, just a hair to the right of the -15 mark.

When I play a 0db sine wave, the needle pegs at +3! I thought Toby had said that only a square wave could push it that high, or was I reading it wrong?

Anyway, I love it! Very cool!

Could you send me the files you are using please?

Thanks