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• Raspberry Pi Camera feedback freezes when moving NEMA 17 stepper motor with A4988 stepper motor driver [closed]

  31 août 2023, par Broteen Das

  I have a Raspberry Pi with a camera module and a NEMA 17 stepper motor connected to it. When I run the command ffplay /dev/video0, the video runs perfectly. However, whilst the video is running, and I run a script that moves the Stepper motor with the A4988 stepper motor driver, the video feed freezes and needs to be restarted.

  


  At first I thought it was ffmpeg's fault, so I tried viewing the feed with OpenCV, but the same probelem persisted.

  


  I also thought that the CPU prioritization was causing the problem, but this one time, the entire Raspberry Pi froze. The Keyboard, mouse, keys, numlock key, everything was dead (the Numlock light on my keyboard was on, I tried toggling the NumLock, but it did not go off) and so I had to turn off and turn on again the power supply to reboot the Pi.

  


  How do I get rid of this issue ?

  


• vulkan/common : Use u32vec2 buffer type instead of u64

  27 novembre 2024, par IndecisiveTurtle

  vulkan/common : Use u32vec2 buffer type instead of u64
  According to the GL_EXT_buffer_reference spec alignment
  
  "must be a power of two and be greater than or equal to the largest scalar/component type in the block."
  This means by using u32vec2 we can drop the requirement alignment from 8 bytes to 4 bytes
  
  and save a pack64 call in reverse8 (though I assume in most ISAs that compiles to nothing)
  Allows the vc2 vulkan encoder to function without setting PB_UNALIGNED
  

  • [DH] libavcodec/vulkan/common.comp

• Why are the colors transposed in my webm thumbnails ?

  9 décembre 2022, par Peter Chaplin

  I have been using ffmpeg to generate webm files from png frames, and the webm files run ok in my video player, but the thumbnail colours appear transposed - blue replacing red, purple replacing orange, brown replacing green. I've also encountered issue uploading the webm to an image hosting site (which normally does support webms), though this might be an issue on their end.
I'm on Ubuntu 22.04.1 LTS

  


  Does anyone know what might be causing this, and how to fix it ? Or how to check whether the webm files are ok or corrupted ?

  


  *Edit : ok, here's a side-by-side comparison of the thumbnails that appear in my file explorer - mp4 on the left and webm on the right.
Both were generated from the same set of pngs, using the same command except with the filename extension changed.

  


  

  


  Specifically,

  


  ffmpeg -framerate 24 -i Panel2Humanized/frame%04d.png panel2humanskin.webm


  


  and

  


  ffmpeg -framerate 24 -i Panel2Humanized/frame%04d.png panel2humanskin.mp4


  


  Both look the same when opened with a video player. It looks like the mp4 thumbnail grabbed the 1st frame while the webm grabbed the last, but the colors should be the same in each. (The text-bubble in the top-left is yellow in the mp4).

  


  *Follow-up : Apparently my WebMs are being generated in GBRP (Green-Blue-Red Planar) pixel format, the site I was trying to upload to requires YUV420P (Luma/Chroma 4:2:0 Planar) format, maybe that's the issue ? I'm still not sure exactly what that means or how to fix it.

  


  *Final follow-up : Looks like I needed to change the argument to :

  


  ffmpeg -framerate 24 -i Panel2Humanized/frame%04d.png -pix_fmt yuv420p paned2humanskin.webm