6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Stereo camera PI processing

Tue Jan 21, 2020 11:12 am

6by9 wrote:
Tue Jan 21, 2020 9:21 am
HermannSW wrote:
Tue Jan 21, 2020 8:58 am
Direct output of Raspberry v2 camera on HDMI monitor has latency of 66ms(!):
https://www.raspberrypi.org/forums/view ... 6#p1573596
Possibly, but you're also now including the refresh rate of your phone display in the equation as well. If that's only running at 60Hz, then your source has a 16ms granularity.

What you really need to measure the latency is one of the calibration devices that has a sequence of running dots that illuminate at fixed intervals (typically 1, 2, or 5ms). I can't remember the product name, but I have one on my desk.
Magic box: LED-PANEL from Image Engineering https://www.image-engineering.de/produc ... -led-panel
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
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HermannSW
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Re: Stereo camera PI processing

Tue Jan 21, 2020 12:44 pm

6by9 wrote:
Tue Jan 21, 2020 11:12 am
6by9 wrote:
Tue Jan 21, 2020 9:21 am
What you really need to measure the latency is one of the calibration devices that has a sequence of running dots that illuminate at fixed intervals (typically 1, 2, or 5ms). I can't remember the product name, but I have one on my desk.
Magic box: LED-PANEL from Image Engineering https://www.image-engineering.de/produc ... -led-panel
Nice piece of hardware, and I see why you have such a professional 1550€ device.
But for hobbyist a bit expensive ;-)
Possibly, but you're also now including the refresh rate of your phone display in the equation as well. If that's only running at 60Hz, then your source has a 16ms granularity.
No phone display in my measurement, that is the reason why I pointed to my previous posting.
Camera records HDMI display itself with very fast running millis.c, that does 58,000 console display updates per second.
But your argument with 60Hz refresh and off being 0-16ms is valid.
The screenshot I showed was minimal value, so display refresh delay near 0ms (I saw 79ms delays as well):
https://www.raspberrypi.org/forums/view ... 6#p1573596
Image
⇨https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264
https://github.com/Hermann-SW/fork-raspiraw
https://twitter.com/HermannSW

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