Dimmer levels

[P. Short]

Does vixen make any effective use of hardware that supports more than 100 (or 101) levels of dimming? I've been wracking my brain over the last year or so trying to make all of my hardware support 256 levels of dimming, and I'm wondering if that was necessary.

--

Phil

[KC]

The editor uses percentage levels strictly for ease of use as a lot of people who would be using it wouldn't understand 256 levels and why it has to be. However, everyone understands percentages.

So the short answer is no. It could, if need be, but it does not.

[P. Short]

Is the information stored internally as 256 levels (and converted back down to 100 levels for the GUI and for the Firegod plugin), or is stored as 100 levels (and converted back to 256 levels for the Renard and DMX plugins)? Are there any scenarios where it makes a difference?

I'm not pushing for it one way or another, since I haven't played around with it nor have I heard any complaints, I'm just asking.

--

Phil

[KC]

It's stored as 256 levels and converted to and from 100 levels for the UI.

[RJ]

I guess thats a new problem then for us who are working on dmx solutions. if we attach dmx stuff we wont be able to fully control them.

[A Marchini]

I guess thats a new problem then for us who are working on dmx solutions. if we attach dmx stuff we wont be able to fully control them.
Which may beg the question, Can a human eye actually tell the difference?
I suppose someone could actually test this.
Doing a ramp over various periods of time in fractional parts of 255 and 100 and seeing if it really "looks" different might be the way to settle it.

[KC]

I guess thats a new problem then for us who are working on dmx solutions. if we attach dmx stuff we wont be able to fully control them.
Not quite true (potentially). An editor could choose to ignore that data completely and implement its own data storage more suitable to the paradigm its implementing. That's only way that I could get LedTriks to work.

[ErnieHorning]

If you think of the dimming values as totally linear, then you need most of the 255 values; you can lop off a few at the top and bottom. The steps are most noticeable at the lower end. If you linearize the dimming curve, so that the steps appear to have a linear affect on an incandescent bulb, you can use as few as 64 steps if you dim slowly. I also found that you only needed 32 steps if you dimmed rather quickly, such as you would do with chasing mini trees.

Since Vixen uses percentages, it could just as well apply a formula or a look-up table (dimming curve) and 0 to 100% would look more like 0 to 100%. A dimming table could contain only the values 0 to 63. Even though there would be 100 positions, only 64 values would be used and some would be the same value.

I’m pretty sure that KC will be adding a dimming curve feature to Vixen 2.0, so this would solve your dilemma.

[RJ]

Maybe If I explian what I mean. Some of us are using DMX to build are shows. This would mean other DMX equipment that expect 256 differet outputs not just dimmers. Some of the equipment have there own built in curves so adding another wont help. What we need is to support true DMX with the ability to output 0 - 255 on any channel. On top of this I have a new dimmer I'm building around DMX that does not have the limitation on the bottom and the top so it can dim linearly. I can see a difference in 100 step to 256 steps if the fade is slow not when fast true but a slow fade on a linear setup does look better. I knew Vixen supported DMX and since the DMX standard calls for 256 levels I believed vixen would output it. Some DMX equipment use channels for position information this will limit there movement to 40% or so in each axis. If vixen wont do it, it wont do it. I will simply have to find a different way to control the stuff. I just believe DMX is the future as it is well suited to the lighting arena being designed for it. It is used by all professional lighting people. Its simply and open. And it would allow one protocol to rule them all (lord of the rings joke.) it has a high channel count, low event timing, and great distance, and allows us to hook other commercial equipment right up to our systems and use them seamlessly, or so I had hoped. This was my thinking behind it.

[P. Short]

Best to just put this in as a change request...

--

Phil

[RJ]

It has been done as requested by Phil.

[DynamoBen]

OK folks lets take a step back for a second.

First off the Vixen DMX plug-in outputs 0-255 for each and every DMX channel. It is true that the UI only displays 0-100%, and yes if you do the first grade math you end up with 155 missing values. So where do they go?

Well they aren't gone. Like all professional lighting equipment the percentage is rounded to the next whole number but the output is not. So while the UI increments from 50% to 51%, the DMX output is moving one value at a time from 128-130.

As far is the human eye noticing the difference between 100 steps vs 255 steps; it is completely noticeable. As a "professional lighting guy" I have seen the difference. With a 100 step fade it looks "steppy” however a 255 step fade is nice and smooth.

[RJ]

Ok I guess I was not thinking sure it goes from 0 to 255 it just skips some. Although this is less of a problem with the dimmer than I was thinking. Other than it wont be as smooth it still creats a problem for the other DMX stuff I'm working with because it means some positions will jump instead of move to.

Thanks for the brain jump start. I need that as i wasn't thinking clearly about it. I put in a request to have KC look at giving the option to work with all 256 levels

[P. Short]

This does make me a reluctant to consider hardware or firmware that is limited to 100 levels. My thought was that if Vixen had been limited to 100 levels all along without any visible problems, then perhaps limiting hardware or firmware to 100 levels would be OK. But if Vixen performs interpolation when ramping, and if 100 levels leads to a 'steppy' display, then I think that I should reconsider.

--

Phil

[DynamoBen]

An 8 bit dimmer (0-255) is the way to go.

At some point in the thread there was a mention of position information with DMX. While its possible to run this stuff with the current plug-in you may run into a small problem. The problem is vixen doesn't provide an easy way to control 16 bit moving lights. In the case of a 16 bit moving light the Pan and Tilt will actually take up two DMX channels. Every time the second channel goes from 0-100 the first channel increments one value thus giving you values from 0-65535. This method provides smooth movement and accurate positioning.

So in the end while it is technically possible to control anything via DMX, the UI at this point isn't "friendly" to more complicated things like moving fixtures.

[ErnieHorning]

It probably wouldn’t be too big of a deal to modify Vixen to accept a value instead of a percentage. It may be a simple as a check box that determines whether “255/100” is performed or not. A 16 bit value would probably be a bit more major.

I’m not claiming to know anything about DMX, but I thought DMX would accept a start value, an end value and how long it should take to get there. Vixen should be able to determine this on the fly. Then it would be left to the equipment to do it smoothly.

[DynamoBen]

DMX has no real intelligence. It just is a series of 512 values that can be 0-255 each.