I have implemented MMAL component graph with PREVIEW port as a source to "ril.isp" as resizer.
This works.
Now that everything in MMAL part works as expected, I want to address the speed issue.
First thing to address is the number of frames per second that I get from PREVIEW->RESIZER chain.
I currently see two ways of how I control number of frames output by preview:
There is a structure, sent to MMAL by parameter MMAL_PARAMETER_CAMERA_CONFIG. Inside it has a field - "num_preview_video_frames",
In RaspiVid.c there is a formula that has to mean something, but I don't understand the point of it
https://github.com/raspberrypi/userland ... 1-L1585C80Suppose state->framerate is 30, then num_preview_video_frames becomes 3.
but then there is also framerate of video inside of a format structure. Should they be the same?
I've tried now to set framerate to preview to 30, but then the hole component and port enabling failed.
Is there some limitation on preview fps?
Also, I observe a huge lag, when I use preview port in combination with "ril.isp" with RGB24 / RGB565 as output, with resizing from 1280x1024 to 320x240. The delay is approximately 3 seconds.
If i remove "ril.isp" from the chain and set camera frame size originally to 320x240, then the draw lag is about 250ms which is poor but probably ok
If I use just a video port in 320x240 with 25fps - everything runs much smoother and real-time.
This works.
Now that everything in MMAL part works as expected, I want to address the speed issue.
First thing to address is the number of frames per second that I get from PREVIEW->RESIZER chain.
I currently see two ways of how I control number of frames output by preview:
There is a structure, sent to MMAL by parameter MMAL_PARAMETER_CAMERA_CONFIG. Inside it has a field - "num_preview_video_frames",
In RaspiVid.c there is a formula that has to mean something, but I don't understand the point of it
https://github.com/raspberrypi/userland ... 1-L1585C80
Code:
.num_preview_video_frames = 3 + vcos_max(0, (state->framerate-30)/10) but then there is also framerate of video inside of a format structure. Should they be the same?
I've tried now to set framerate to preview to 30, but then the hole component and port enabling failed.
Is there some limitation on preview fps?
Also, I observe a huge lag, when I use preview port in combination with "ril.isp" with RGB24 / RGB565 as output, with resizing from 1280x1024 to 320x240. The delay is approximately 3 seconds.
If i remove "ril.isp" from the chain and set camera frame size originally to 320x240, then the draw lag is about 250ms which is poor but probably ok
If I use just a video port in 320x240 with 25fps - everything runs much smoother and real-time.
Statistics: Posted by valc — Wed May 22, 2024 7:19 pm