Author Topic: Frame rate for wave export  (Read 2426 times)

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Offline ojovijo

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Frame rate for wave export
« on: August 15, 2017, 06:21:07 pm »
I'm confused about how LB renders WAV files. I'm importing a directory of DXF files (with lots of vertices) and have the frame rate at 16 fps. I'd like each image to display for 1/16 second, but after saving the wave file it lasts for rather longer than (numberofframes/16) seconds. I'm doing this with o/3/4 or o/3/8 (and I don't really follow the difference between these).


(I'm aiming to display things on an oscilloscope or vector monitor rather than lasers.)

Clearly I'm missing something - presumably the distinction between a LB frame and a video frame. Can anyone clarify?


/* thanks to James for a great program, by the way */

Offline James

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Re: Frame rate for wave export
« Reply #1 on: August 15, 2017, 07:23:02 pm »
Hello ojovijo. Wecome to The LaserBoy Forum!

First of all, LaserBoy does not omit any data from frames when it makes waves. So if you consider the fact that a wave is 48 thousand samples per second and 1/16 of that is 3000... If your frames have more than 3000 points, LB will take longer than 1/16 of a second to display those frames.

LB looks at each frame and shows it in a wave at least one whole time. It only repeats a frame if the frame has few enough points to be less than the time it takes to show the frame for 1/frames-per-seconds. And even then it shows whole frames; never partial frames.

That said, if you are making waves for a vector scope you really don't need to worry about optimization; although it will effect the weight of your lines. At least you don't have to worry about burning up your scanners!

You could try making waves that are not optimized for scanners. That might make them display a little faster.

Also, what settings are you using in menu x?

Take a look at options 7 8 and 9 in menu x.

For DXF import you want these all to be on!

This might reduce your total points per frame quite a bit.

Can you share an example of your DXF art?

James.
« Last Edit: August 15, 2017, 07:25:56 pm by James »
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Offline ojovijo

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Re: Frame rate for wave export
« Reply #2 on: August 15, 2017, 07:44:44 pm »
Thanks for your reply!


I'm writing the wave at 96 kHz, so at 16fps that's 6000 samples per frame.


Suppose a frame has 5000 points, what I'd like it to do is output those points then the first 1000 again, so that the next image can be displayed exactly 1/16 second later. But if LB never writes partial frames then I presume this isn't possible. I can find a workaround for this.


Currently the x menu uses options 1234ahj - I'll look into 789 as you suggest.


Offline James

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Re: Frame rate for wave export
« Reply #3 on: August 15, 2017, 08:05:00 pm »
LB was designed to make waves that are safe for scanners, so no there is no way to display a whole frame and then just the first 1000 points before going off to the next frame.


LB puts transitions in between the frames to make sure the scanners never exceed a predetermined velocity.


James.
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Offline James

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Re: Frame rate for wave export
« Reply #4 on: August 15, 2017, 10:20:33 pm »
After you turn on options 7, 8 and 9 in menu x, go into menu h and hit capital K to minimize all the frames. It might take a little while to get it done, but you will end up with the minimum number of points possible.

Then you can use o 3 4 to make a wave of the minimum number of points per frame. But don't play it into a real set of scanners!  :o

James.
« Last Edit: August 15, 2017, 10:42:24 pm by James »
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Offline James

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Re: Frame rate for wave export
« Reply #5 on: August 17, 2017, 04:40:24 pm »
Can you share some pictures of what you are working on?

Thanks!

James.
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Offline ojovijo

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Re: Frame rate for wave export
« Reply #6 on: August 18, 2017, 08:47:43 am »
I'm trying to vectorise video. Still lots of tweaking to be done. An example is attached. (Not great quality for many reasons - it's 48-kHz output as I can't currently do both DC coupled output and 96 kHz.)
« Last Edit: August 18, 2017, 08:53:54 am by ojovijo »

Offline James

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Re: Frame rate for wave export
« Reply #7 on: August 18, 2017, 12:43:28 pm »
Looks like you're getting somewhere.

Does your scope have in intensity input?

You might be able to blank out the connecting lines.

There is a setting in LB to put O-Scope blanking in the 6th channel of a wave.

But that means you need a modified sound device that has at least 6 channels.
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