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Cam output on Monitor without Latency

Posted: Wed Jun 05, 2019 8:57 am
by BenzW
My goal:
-Live Preview of the Rasperry Pi Camera (Without Network/Stream)
-Latency ~10ms

My hardware:
-Raspberry Pi 2
-Raspberry Pi Camera

Question:
Is is possible to achieve the goals with the mentioned hardware?
I tried die python "camera.start_preview" script, but the delay was way to high (~100ms).

Greetings! :D

Re: Cam output on Monitor without Latency

Posted: Wed Jun 05, 2019 9:06 am
by jamesh
raspivid is about as fast as you can get with regard to latency. Note though that at 30fps, each frame is 33ms, and I think there is one frame delay before it gets to the display. You could reduce the resolution, and up the frame rate to decrease latency.

Re: Cam output on Monitor without Latency

Posted: Wed Jun 05, 2019 9:06 am
by RaTTuS
use the rpi hdmi ?

Re: Cam output on Monitor without Latency

Posted: Wed Jun 05, 2019 9:45 am
by BenzW
jamesh wrote:
Wed Jun 05, 2019 9:06 am
raspivid is about as fast as you can get with regard to latency. Note though that at 30fps, each frame is 33ms, and I think there is one frame delay before it gets to the display. You could reduce the resolution, and up the frame rate to decrease latency.
I tried it, but I get a strange phenomenon:
If I type "raspivid -t 10000 -w 400 -h 400 -fps 60 -vf -hf -o test1.h264" I get a perfect video with nearly no latency. But thats not exactly what I want.
This Command "raspivid -t 0 -w 400 -h 400 -fps 60 -vf -hf" just gives me the cam-output and doesn't save it. But there is more latency and the image in general looks very different.

Re: Cam output on Monitor without Latency

Posted: Wed Jun 05, 2019 11:38 am
by jamesh
BenzW wrote:
Wed Jun 05, 2019 9:45 am
jamesh wrote:
Wed Jun 05, 2019 9:06 am
raspivid is about as fast as you can get with regard to latency. Note though that at 30fps, each frame is 33ms, and I think there is one frame delay before it gets to the display. You could reduce the resolution, and up the frame rate to decrease latency.
I tried it, but I get a strange phenomenon:
If I type "raspivid -t 10000 -w 400 -h 400 -fps 60 -vf -hf -o test1.h264" I get a perfect video with nearly no latency. But thats not exactly what I want.
This Command "raspivid -t 0 -w 400 -h 400 -fps 60 -vf -hf" just gives me the cam-output and doesn't save it. But there is more latency and the image in general looks very different.

I just tried that, looked OK to me. No difference in the two commands that I could tell. What differences are you seeing?