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@Hermann-SW
Last active March 28, 2025 13:54
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tool for playing with Raspberry Pi Global Shutter Camera crop values
#!/bin/bash
# shellcheck disable=SC2154
# (silence shellcheck wrt $cam1 environment variable)
if [[ $# -lt 4 ]]; then echo "Format: [narrow=1] [cam1=1] $0 width height framerate ms [us]"; exit; fi
if [[ "$(( $1 % 2 ))" -eq 1 ]]; then echo "width has to be even"; exit; fi
if [[ "$(( $2 % 2 ))" -eq 1 ]]; then echo "height has to be even"; exit; fi
export SHTR=""; if [[ $# -gt 4 ]]; then SHTR="--shutter"; fi
export workaround=""; if [[ "" != "$(grep '=bookworm' /etc/os-release)" ]]; then workaround="--no-raw"; fi
export d=10; if [[ "" != "$(grep "Revision.*: ...17.$" /proc/cpuinfo)" ]]; then if [[ "$cam1" == "" ]]; then d=10; else d=11; fi; fi
for((m=0; m<=5; ++m))
do
media-ctl -d /dev/media$m --set-v4l2 "'imx296 $d-001a':0 [fmt:SBGGR10_1X10/${1}x${2} crop:($(( (1440 - $1) / 2 )),$(( (1088 - $2) / 2 )))/${1}x$2]" -v; [ $? -eq 0 ] && break
done
libcamera-hello --list-cameras ;echo
rm -f /dev/shm/tst.pts
if [[ "" != "$(grep "Revision.*: ...17.$" /proc/cpuinfo)" ]]
then
rpicam-vid "$workaround" ${cam1:+--camera 1} --width "$1" --height "$2" --denoise cdn_off --framerate "$3" -t "$4" "$SHTR" "$5" -o /dev/shm/tst${cam1:+1}.mp4 -n ;echo
~/venv/bin/python ~/rpicam-apps/utils/timestamp.py --plot ${narrow:+--narrow} /dev/shm/tst${cam1:+1}.mp4
else
libcamera-vid "$workaround" --width "$1" --height "$2" --denoise cdn_off --framerate "$3" --save-pts /dev/shm/tst.pts -t "$4" "$SHTR" "$5" -o /dev/shm/tst.h264 -n ;echo
rm -f tstamps.csv && ptsanalyze /dev/shm/tst.pts
fi
@Hermann-SW
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Latest revision fixed two problems (device numbering for cam1, media-ctl command to be used) to make GScrop work again:
https://forums.raspberrypi.com/viewtopic.php?p=2301063#p2301063

@paprikodlak
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paprikodlak commented Mar 13, 2025

Hi,
thank you for this work.

First, I was not able to capture anything, because the camera would not set up. Then I studied the script and the "no raw workaround" pointed me to the right direction. To capture using picamera2, the raw stream needs to be disabled when configuring.

Copilot was able to convert the script to python, for those interested.
https://gist.github.com/paprikodlak/0f55438ec000157a43e1d3612a00b919

It also includes a script I am using for square cropped capture.

@Hermann-SW
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Hermann-SW commented Mar 25, 2025

@paprikodlak Please create a gist named "GScrop.py" and replace your comment above with a short description and link to that gist.
Then it can be found via this gist, but is separate.

@Hermann-SW
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Hermann-SW commented Mar 25, 2025

Two big news for using GScrop.

  1. running GScrop to set crop, and then directly rpicam-vid with --codec yuv420 and same width+height allows to process frames on the fly (at 527fps for a simple example) while being captured:
    https://forums.raspberrypi.com/viewtopic.php?p=2305225#p2305109
  2. much bigger frames can be captured @536fps than 224x96 — frameskipless capturing of 1456x96@536fps is possible (yes, full sensor width)! This is 50% reduced in size screenshot of mplayer playing video recorded with GScrop:
    https://forums.raspberrypi.com/viewtopic.php?p=2305225#p2305205
    image

@Hermann-SW
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Hermann-SW commented Mar 25, 2025

  1. passing optional parameter 100 to GScrop allows to set shutter speed to 100µs:
    GScrop 1456 96 536 2000 100
    That allows to capture >40m/s inflight airsoft pistol pellet without too much distortion.
    This can be seen in two of the 5 frames of below animated .gif (only left frame half, with 1.87ms between frames):
    https://forums.raspberrypi.com/viewtopic.php?p=2305225&sid=c396d0ec32f4c37dfd1aa56aa2758dbd#p2305225
    pellet anim
    The animated .gif only has 256 colors, so makes the frames look uglier than real.
    This is the left frame half of last of the 5 frames only as captured for comparison.
    A bit dark because of 100µs shutter time, but everything but the >40m/s inflight pellet is sharp:
    4

@Hermann-SW
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Hermann-SW commented Mar 28, 2025

GScrop can also be used as simple tool to set crop and framerate for other processing.

This posting describes a processing pipeline with all the details:
https://forums.raspberrypi.com/viewtopic.php?p=2306078#p2306078

In short it does this:

  1. captures 224x96@536fps yuv420 video and pipes to next command
  2. determines dark/bright for each frame while it is streamed and writes to file "err"
  3. ffmpeg converts the yuv420 video to .mp4

image

Despite the quite concurrent processing, recorded framerate only dropped to 527fps from 536fps.

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