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by 6by9
Tue Jun 18, 2019 5:22 pm
Forum: Camera board
Topic: open discussion on the camera latency
Replies: 7
Views: 1789

Re: open discussion on the camera latency

Please read the docs on how the camera subsystem and rolling shutter sensors work - https://picamera.readthedocs.io/en/latest/fov.html It looks like the exposure and readout takes a significant amount of time. I am not 100% sure why. Physics. You have to take some time to sample the photons received...
by 6by9
Tue Jun 18, 2019 1:47 pm
Forum: Camera board
Topic: Custom image filter with picamera
Replies: 4
Views: 115

Re: Custom image filter with picamera

PiCamera has set everything up to expect the input to components to be a connection from another component. Typically the original source will have been the camera component, which requires no other input. It only registers user callbacks for the output data. image_encode (which is what you want) ha...
by 6by9
Tue Jun 18, 2019 9:19 am
Forum: Camera board
Topic: Text overlay over split screen live preview
Replies: 3
Views: 88

Re: Text overlay over split screen live preview

Thanks gordon77. I was expecting errors, hence being reluctant to spend the time trying to run it myself. add_overlay is a function of the PiCamera class, not MMALCamera https://picamera.readthedocs.io/en/latest/api_camera.html#picamera.PiCamera.add_overlay The code for it is trivial though, so a qu...
by 6by9
Tue Jun 18, 2019 7:53 am
Forum: Camera board
Topic: Text overlay over split screen live preview
Replies: 3
Views: 88

Re: Text overlay over split screen live preview

What "doesn't really work"? Please describe the results you do get.
At a guess your layering is wrong, but it would take a fair amount to recreate. You can use "vcgencmd dispmanx_list" to see the list of elements that have been requested to be put on the screen.
by 6by9
Tue Jun 18, 2019 7:46 am
Forum: Camera board
Topic: Custom image filter with picamera
Replies: 4
Views: 115

Re: Custom image filter with picamera

OpenCV is hideously slow for many operations, and has no hardware acceleration. JPEG and MJPEG also generally operate on yuv data, not rgb, therefore you have a format conversion to be done too. You ought to look at the MMAL encoder options. PiCamera does expose some of those (https://picamera.readt...
by 6by9
Tue Jun 18, 2019 7:40 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: WiringPi and I2C BME280
Replies: 5
Views: 143

Re: WiringPi and I2C BME280

ioctl(I2C_SLAVE) only updates the address to be used in subsequent transactions, it does not perform any communication with the device at that point, and therefore doesn't know whether the device is present or not. When you try to do a read or write to the device, that will fail as the device will n...
by 6by9
Mon Jun 17, 2019 4:40 pm
Forum: Graphics, sound and multimedia
Topic: Which single board computer for path recognition with OpenCV?
Replies: 1
Views: 44

Re: Which single board computer for path recognition with OpenCV?

These forums are provided by Raspberry Pi for the support of their products. Support or recommendations of other products is outside their scope. I'd suggest you do your development on whatever you have, and once you have it working look to optimise it for an SBC. OpenCV is a seriously heavyweight a...
by 6by9
Mon Jun 17, 2019 4:10 pm
Forum: Camera board
Topic: Convert MJPEG output to mp4
Replies: 5
Views: 164

Re: Convert MJPEG output to mp4

You've said mp4, which is a container format and not a codec. mp4 can hold a huge number of codec formats.

You can put mjpeg into an mp4 container with

Code: Select all

ffmpeg -r 15 -i foo.mjpg -c:v copy bar.mp4
Transcode is a much bigger job, and will be very slow at 8MPix resolution on the CPUs.
by 6by9
Mon Jun 17, 2019 1:36 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Device tree overlays and i2c_vc
Replies: 6
Views: 152

Re: Device tree overlays and i2c_vc

What was the problem here exactly though? Was it simply a mismatch between the compatible string and the aliases of the kernel module? This is probably fixed in newer versions since the default i2c-rtc overlay wouldn't work either? Yes, it's a simple mismatch on the compatible string. I'm not quite...
by 6by9
Mon Jun 17, 2019 11:18 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Device tree overlays and i2c_vc
Replies: 6
Views: 152

Re: Device tree overlays and i2c_vc

Check "/proc/device-tree/soc/[email protected]/[email protected]/status" is "okay", and "/proc/device-tree/soc/[email protected]/[email protected]/compatible" is "maxim,ds1307". Bells are ringing for me now. https://github.com/raspberrypi/linux/issues/2989, however I don't think that is the condition here. "modinfo ds1307" i...
by 6by9
Mon Jun 17, 2019 9:49 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Device tree overlays and i2c_vc
Replies: 6
Views: 152

Re: Device tree overlays and i2c_vc

Changing the target from <&i2c_arm> to <&i2c_vc> in all the fragments, recompiling, and copying to /boot/overlays, should be sufficient. Check the output of dmesg for any evidence of issues when probing the rtc. "vcdbg log msg" will only give information from the firmware as it merges the DT fragmen...
by 6by9
Mon Jun 17, 2019 9:00 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C is broken by latest commit
Replies: 10
Views: 343

Re: I2C is broken by latest commit

Apologies - I'd missed that it had been backported on Thursday. I'd only seen it on the mainline mailing lists.
I'll check to see if Phil has seen any issues.
by 6by9
Sun Jun 16, 2019 6:22 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C is broken by latest commit
Replies: 10
Views: 343

Re: I2C is broken by latest commit

Seeing as I've only just seen that commit accepted into the mainline kernel I suspect you're building off one of the upstream staging branches, and not a release. In which case all bets are off, and any issue ought to be reported upstream to the maintainers and mailing lists (linux-rpi-kernel, and l...
by 6by9
Sun Jun 16, 2019 12:33 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPU RAM Interface
Replies: 1
Views: 98

Re: GPU RAM Interface

ARM and gpu both access ram through the same bus infrastructure.
The codecs write their data to sdram (generally as yuv), and the composition pipeline takes that frame and others to generate the hdmi (or other) output on the fly.
by 6by9
Sat Jun 15, 2019 9:41 am
Forum: Camera board
Topic: Camera dropping frames, any advice?
Replies: 16
Views: 570

Re: Camera dropping frames, any advice?

I also tried playing the .h264 version of the video within omxplayer, but instead of showing artifacts, the video played at a rapid speed. When there are no timestamps, omxplayer plays back as fast as it can decode the frames. With a VGA resolution frame, that's pretty quick. 1080p would end up bei...
by 6by9
Sat Jun 15, 2019 9:35 am
Forum: Camera board
Topic: Pi 3 B+, v2.1 camera abyssmal fps @1080p
Replies: 12
Views: 375

Re: Pi 3 B+, v2.1 camera abyssmal fps @1080p

@6by9 or @jamesh might know why some frames less than you expect get recorded. When you request video capture the system has to switch modes. If currently streaming, that means: - completing the current frame first (NB this may not be at the same frame rate as your recording) - stopping the sensor ...
by 6by9
Sat Jun 15, 2019 7:54 am
Forum: Camera board
Topic: Scrolling Horizontal Blur
Replies: 7
Views: 218

Re: Scrolling Horizontal Blur

LEDs follow the input even faster than the phosphor in fluorescent lights, so it really depends on the driver. If it converts to DC to drive the LEDs (as Hermann's does) then you'll get 0 variation. If it half wave rectifies and then current limits, you'll get significant variation still. 60Hz mains...
by 6by9
Fri Jun 14, 2019 8:55 am
Forum: Camera board
Topic: Scrolling Horizontal Blur
Replies: 7
Views: 218

Re: Scrolling Horizontal Blur

If it is more, then use the -fl option to specify the mains frequency, and ae will choose exposure times that are a multiple of the flicker period. I had seen mains flicker myself in the past and was not aware how to overcome that with a raspivid option (I bought led drivers that deliver DC to the ...
by 6by9
Fri Jun 14, 2019 6:26 am
Forum: Camera board
Topic: Scrolling Horizontal Blur
Replies: 7
Views: 218

Re: Scrolling Horizontal Blur

Mains flicker. Your illumination is most likely fluorescent lights which flash at twice the mains frequency (once for each half cycle). The sensor is a rolling shutter sensor, therefore not all lines expose at exactly the same moment. If the exposure time is not a multiple of a mains half cycle then...
by 6by9
Thu Jun 13, 2019 7:44 pm
Forum: Off topic discussion
Topic: 3B+ has some competition
Replies: 5
Views: 433

Re: 3B+ has some competition

That link says 1080p on the hdmi output, and only 100Mbit ethernet.
Having options is always a good thing.
by 6by9
Thu Jun 13, 2019 9:47 am
Forum: Compute Module
Topic: CM3 DPI connection
Replies: 6
Views: 218

Re: CM3 DPI connection

I'll draw your attention again to the config line dpi_output_format=0x6f005 As per the documentation, bits 0-3 control the mode. You have them set to "5", therefore you are selecting mode 5 which is RGB666 (18bit mode), NOT mode 7 for RGB888 (24bit mode). With mode 5 you'll be displaying the least s...
by 6by9
Wed Jun 12, 2019 2:13 pm
Forum: Compute Module
Topic: CM3 DPI connection
Replies: 6
Views: 218

Re: CM3 DPI connection

Your choice of file sharing site isn't nice seeing as Google gives all sorts of warnings about it. I've resized and added the image directly as the details isn't required. To my eyes that is simply that you've got the wiring wrong. There is no standard wiring for DPI displays, therefore you have to ...
by 6by9
Wed Jun 12, 2019 1:05 pm
Forum: HATs and other add-ons
Topic: PiTV + Tvheadend = some streams sound only
Replies: 6
Views: 190

Re: PiTV + Tvheadend = some streams sound only

As I'd posted earlier, there is a hardware assisted HEVC decoder built as an extension to FFmpeg. It requires a specific way of driving it for buffer allocation and similar, therefore I don't believe it is in the default Raspbian build, but it is in LibreElec.
by 6by9
Wed Jun 12, 2019 1:04 pm
Forum: Camera board
Topic: Pi 3 B+, v2.1 camera abyssmal fps @1080p
Replies: 12
Views: 375

Re: Pi 3 B+, v2.1 camera abyssmal fps @1080p

If you are analysing the timestamps file, please ensure you have picked up the latest version of userland. A bug was fixed recently in https://github.com/raspberrypi/userland/pull/553 where should an encoded frame be be fragmented into multiple buffers then the timestamp wasn't written to the pts fi...

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