Raspberry Pi Forums

cpunk

Since this bit took me a few hours to code, I thought I'd try to save time for others in case they try similar ventures. :) Basically, I got some APA102 LEDs and needed to implement blinking lights and a continuously rolling rainbow with them. The program needed to be in Java, as the rest of my syst...

cpunk

The lift of that thing in case of helium: approximately 1 g / L (or alternatively, kg / m3). With hot air, about 10 times less, maybe 0.1, as hot air is comparatively dense, not much lighter than ordinary air. As for volume, if we assume it's a cylinder, then volume = base area * height. Base area w...

cpunk

The (fresh) water resistance of unprotected electronics is quite surprising sometimes (at low voltage?). :D But salt water does things quickly. I have once landed a foam glider in sea, and within the 7 seconds it took me to disconnect power, the receiver and motor controller had already conducted a ...

cpunk

Quite impressive for such a small plane. :) I'm used to them blowing away with wind. :D

cpunk

Hello, Can you please confirm that your camera is working in normal mode (without this command line switch)? I added the command line option for flicker avoidance, and it was a simple userland change, no firmware was involved at all. Also, can you try if the short command line option (e.g. "-fli 50h...

cpunk

Tested. :) Works beautifully. Thank you! :)

cpunk

Thank you, will test it this evening. :) If I can cut Gstreamer entirely out of the game and refactor the drone's entire video feedback subsystem to broadcast RGB scanlines in packet injection mode (ground station listening in monitor mode), I should have an rather low latency and highly robust vide...

cpunk

Relays you can easily connect to GPIO pins - there are plenty of relay cards available, starting from 1 relay and ending with 10 relays, I think... Sensors... unless you mean simple on/off sensors, I would recommend looking for I2C-connectable versions, and connecting them to the I2C pins. There are...

cpunk

Wow, nice. :) If you need testers at any point, just drop a line here - I would definitely be interested in trying (although I don't think I have ever compiled firmware for anything GPU-related - only to put the WiFi card in packet injection mode).

cpunk

P.S. Maybe this problem of getting YUV instead of RGB is specific to low resolutions?

cpunk

Or alternatively, just put a package of moisture-absorbing silica granules along with electronics into the box. Might also help, but needs regular (yearly?) replacement.

cpunk

P.S. I also have:

Code: Select all

raspivid Camera App v1.3.12

cpunk

Thanks for trying... it is strange to hear that somewhere, it is outputting RGB. So I tried recreating that (but could not). First I reinstalled the following packages: libraspberrypi-bin libraspberrypi0 raspi-config Output was: (Reading database ... 70121 files and directories currently installed.)...

cpunk

Maybe you are accidentally forcing V4L to convert the video from one size to another (or one pixel format to another)? If that happens, it will do that using CPU resources. Meanwhile, "raspivid" lets the GPU do such things...

cpunk

Not sure if it's legal in the country you reside in (it has 33dBm of RF output), but I'm using the E31-TTL-2W from CDE for more than just hobby projects, but also industrial telemetry and a prototype environmental monitoring mesh. It's a narrow band radio modem with adjustable frequency channels. No...

cpunk

Tried it, but no remarkable delay here. :)

cpunk

Thank you. :)

For me, it was a fortunate mishap, as due to swapping kernels back and forth trying to figure things out, I found and patched a juicy bug in my own video analysis code. :)

cpunk

Wow, thanks for the detailed info. :) And sorry for "barking up the wrong tree", at the time of writing I didn't figure out that there was library embedding going on, and that simply setting a system property could override it. :) :D

cpunk

Also, GRAY8 (-rf gray) is working as intended. :) However, since the source code suggests that GRAY8 is produced by actually running in I420 mode and sending the leading part of the buffer instead of the whole buffer, I guess I should not be surprised. :)

cpunk

I can additionally confirm that even if I override the choice between RGB and BGR, and tell it to always output BGR, it still gives me YUV. The nice thing is that I can decode the YUV like this: public class YuvToRGB { private static int R = 0; private static int G = 1; private static int B = 2; pub...

cpunk

I am confident that "format->encoding" is set by "create_splitter_component(RASPIVID_STATE *state)". I think this is not a command line parsing problem.

cpunk

I get the same output if I tell Gstreamer to decode H264 into I420. So I think it must be I420 ("8 bit Y plane followed by 8 bit 2x2 subsampled U and V planes", according to: https://www.fourcc.org/pixel-format/yuv-i420/ ). My versions over here are: # vcgencmd version Feb 20 2017 14:01:24 Copyright...

cpunk

I have recreated it - definitely not the kind of RGB8 that Gstreamer outputs. Much more likely YUV or some similar format. I will try to search for it tomorrow, although I am very new to "raspivid" source code, having modified it only once before (so please don't count on me to solve it, I am more l...

cpunk

For such a high frame rate, the pictures are remarkably light and contrastful. :) I wonder what tricks you are using to achieve that? :) Are you using very intensive lights?

cpunk

Interesting... I will try to recreate the effect on my system, since at some point, I would also be interested in shifting the work of producing RGB to hardware instead of Gstreamer (which I'm using currently).

I'll mention if I see something that draws attention.

Search found 85 matches

Code sample: rolling rainbow on APA102 LEDs from Java

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