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Thread: The LaserBoy Thread

  1. #111
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    If you think about it for a minute you'll see there are some real issues when it comes to converting waves back into color vector art.

    The output a any DAC is more or less a set of analog signals. If you record that with an ADAT or similar multi track recorder, that recorder has no connection what so ever to the DAC clock. The recorder itself will have it's own clock, probably at a fixed rate of 48KHz (maybe 96KHz). So you will end up with vector data that is sampled at 48KHz. That's 48000 samples or points per second; regardless of the laser DAC clock rate.

    This might be the reason for this comment:

    Quote Originally Posted by Laser Wizardry View Post
    I've tried to use laser boy. Ive seen it add extra "vertices" to files off an adat.
    That's not LB adding any extra vertices. It's the ADAT clock.

    Another issue is the time delay between the scanner signals and the color signals. The way you deal with this is by time shifting samples between the channels. So your smallest quantum of time to use as an adjustment is one sample or 1/48th of a second.

    Then there is the issue of framing. That is the most difficult thing to deal with and in many cases there isn't anything you can do except pick some arbitrary number and split up the wave data into that many samples per frame.

    I spent some time looking for a way to identify a big blank spot at the end of each frame, but that technique is easily confused with frames that have lots of blank in them. And not all laser DACs / software use the idea of a time synch blank spot at the end of every frame.

    LaserBoy has a black level setting that lets you specify a number that is close enough to black (0.00 on the red green and blue) to be called black, therefore blank.

    It also lets you set the number of samples to shift in time to align the colors to the scanners per channel.

    You can also set the number of samples you want in each frame.

    You can import waves into the memory model as a frame set or you can just display the wave on the screen either in real time or as fast as your computer can render it.

    Another important thing to note is that you have no way to know if the original ADAT recording was made at full scale. As long as it plays back the same voltages that it recorded, it works as a laser show recorder. But the recording might not go to full scale. So it is a good idea to open your ADAT waves in Audacity and normalize the channels. It's best to select both scanner signals together and normalize them to zero dB. Then you can assume that at least at some point, each one of the color signals will hit full swing. So you can normalize each one of them separately to zero dB. That way, when you import them to LB you'll get a full sized image with the brightest possible colors.

    If anyone knows exactly where DZ's abstract recordings are please post a link.
    Last edited by james; 11-14-2015 at 07:58.
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  2. #112
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    I see a lot of value in coverting z5 abstract output to frames and incorporating those sequences into my LSX timeline for show programming.

    Quote Originally Posted by JohnYayas View Post
    Do the z5 waves have any sort of frame information in them or are they just standard waveforms? If they are just waveforms then they can just be arbitrarily broken up into frames. You could use Dean Hammond's waveform generator if you want to experiment with those types of samples. But, I don't see a whole lot of value in that. The value is being able to take a frame based ADAT and convert that back to discrete frames that start and end where they should and the being able to remove or correct any color shifting and blanking that was added and encoded into the tape. The ultimate would be able to play back existing wave files, live, and be able to handle those color/blanking shifts in real time so that you could adjust them for your projector. For example, lets say they over compensating when recording so it isn't quite right for your projector. Can you decompensate and then adjust so that it looks nice on your projector? I have an ADAT wav file that has some really bad blanking issues when played back directly. I want to be able to play it and make adjustments to it so that it looks right without having to do any preprocessing. That is a stalled side project of mine, unfortunately.

  3. #113
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    Quote Originally Posted by swamidog View Post
    I see a lot of value in coverting z5 abstract output to frames and incorporating those sequences into my LSX timeline for show programming.
    Since these are from a totally analog source, there probably is no notion of frames. So it would be trivial to record the output onto an ADAT or similar HD multi-track recorder and open that as a set of frames with a fixed number of points per frame in LaserBoy and export that as ILDA.

    Let's do it!

    If 48KHz or 48000 points per second is too much for your laser show software, you should be able to open the ADAT waves in Audacity and do a sample rate conversion to something like 20KHz. This would be a very effective way to reduce the total number of points per frame (or per second) and still give you a decent looking image.

    However, if you do a sample rate conversion to something less than 48000 samples per second, you'll need to do some math to figure out how many samples to delay between the scanner and the color signals.
    Last edited by james; 11-14-2015 at 09:20.
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  4. #114
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    Quote Originally Posted by JohnYayas View Post
    The value is being able to take a frame based ADAT and convert that back to discrete frames that start and end where they should and the being able to remove or correct any color shifting and blanking that was added and encoded into the tape.
    I'm curious as to what cues you would look for in an ADAT recording to find the end of frame points.

    At 48KHz, the colors should be 5 samples in time behind the scanner signals. I have found this works on every projector I have had any experience with.

    You can import waves into LB with sample shifting to correct for the color to scanner time alignment. You can also use LB to change the time shift in a multi-channel wave.

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  5. #115
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    Quote Originally Posted by james View Post
    I'm curious as to what cues you would look for in an ADAT recording to find the end of frame points.

    At 48KHz, the colors should be 5 samples in time behind the scanner signals. I have found this works on every projector I have had any experience with.

    You can import waves into LB with sample shifting to correct for the color to scanner time alignment. You can also use LB to change the time shift in a multi-channel wave.

    James.
    It depends on the source. I don't know much about how the old planetarium equipment worked. With some of the software packages you can check for large blanks, a return to zero, bearing movements, or if the frames are at a constant rate you can figure out the break and it will tell you all the frames more or less. It's definitely not a "one size fits all" problem.

  6. #116
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    I just updated LaserBoy.

    The link is in my forum signature.

    I found a bug that caused a crash.

    It was somewhat related to opening waves. If you end up with a frame that is all below the black threshhold and therefore set to all blank, the previous version would crash when you tried to synch the RGB and palette indexes, because it was trying to dereference an array with an index of -1.

    Ooops.

    Fixed it!

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  7. #117
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    I PM'ed DZ and he sent me a link to a flac file he made from his abstract console.

    I opened it in Audacity and found that it only had a red modulation signal. So I copied that track and skewed it in time to create color information for green and blue.

    In LaserBoy, I set option i in the [Tab] menu to 2331 samples per frame and option s black level to 40 and opened the wave I exported from Audacity.

    Then I saved that as ILDA format 5.

    http://laserboy.org/free_art/DZ_fmt5_001.zip

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  8. #118
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    2331 samples is too much for some DACs. Some max out at 1500 which is a bit low, in my opinion.

  9. #119
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    Quote Originally Posted by JohnYayas View Post
    2331 samples is too much for some DACs. Some max out at 1500 which is a bit low, in my opinion.
    That seems like an arbitrary number but it was the predominant period of the waveform. So I got one whole cycloid per frame.

    It is possible to reduce the number of points per frame, but then you lose color modulation.
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  10. #120
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    Thanks, James. I look forward to checking this out. Unfortunately, I wont have access to my DAC for about another week.

    I did create a new recording with changing patterns and color mod, I wonder how this would turn out? It's about 12 minutes long.

    https://drive.google.com/file/d/0BzS...ew?usp=sharing

    Quote Originally Posted by james View Post
    I PM'ed DZ and he sent me a link to a flac file he made from his abstract console.

    I opened it in Audacity and found that it only had a red modulation signal. So I copied that track and skewed it in time to create color information for green and blue.

    In LaserBoy, I set option i in the [Tab] menu to 2331 samples per frame and option s black level to 40 and opened the wave I exported from Audacity.

    Then I saved that as ILDA format 5.

    http://laserboy.org/free_art/DZ_fmt5_001.zip

    James.

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