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Messages - foobar

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Chronos User Discussion / Re: Chronos Ring and ethernet support.
« on: August 28, 2019, 10:04:06 AM »
Yes, the cameras that we have been using in the Chronos ring are all running Debian, with a cople changes to the configuration and packages. The difficulty is that running the network control API, we do not have a GUI working just yet and the only way to control the cameras is through their network interface. This presents a fairly significant loss of general usability, which is why we haven't been shipping this our production cameras.

If you want to try out a camera running Debian, there should be some rough instructions in the README of the chronos-updates repository on how to build and install Debian onto your camera. We recommend doing this on a spare microSD card so that you can still revert back to a working camera by swapping the operating system cards.

Software Dev / Re: Camera powers off after update to 0.3.2
« on: July 24, 2019, 01:46:59 PM »
Also worth noting, you can distinguish between the cause of the reboot by watching the status LED on the top of the camera, it will blink red when the watchdog timer triggers a reboot. If the camera is rebooting for some other reason, such as a thermal overload or when the auto power-off feature is configured the red LED will not blink.

Software Dev / Re: Camera powers off after update to 0.3.2
« on: July 24, 2019, 09:46:06 AM »
That is very troubling, I'm sorry to hear that you've run into a problem like this.

Out of curiosity, does the camera ever show battery information in the bottom right hand corner of the screen before it shuts down? And if so, is the cycle time between the splash screen and the undesired reboot consistent?

When the auto power-on/off modes are disabled, or the camera is on AC power, there should only be two cases where the camera will reboot itself:
  • The main CPU has not made any communication to the power manager firmware within 60 seconds of boot.
  • The power manager firmware has detected an over-temperature condition and shut off power to the system for safety.

The most likely cause is that for some reason the software running on the main CPU is not requesting power information from the power manager firmware within that 60 second window.

Chronos User Discussion / Re: frame straddling
« on: July 17, 2019, 11:50:45 AM »
I'm afraid that this particular pattern of exposure and frame timing will not work. When the camera is operating in gated burst mode the rising edge of the trigger signal starts the exposure for a frame and the falling edge ends the exposure and begins the frame readout. During frame readout, the exposure for the next frame can be started but the exposure must continue for long enough that the falling edge happens after the readout of the first frame completes. A falling edge of the trigger signal while frame readout is in progress will be ignored because the pixel storage nodes on the image sensor are in use and are not able to accept another frame.

Because the image sensor does not have a physical shutter, there is no way to stop or pause the exposure of a frame, the exposure control is actually a signal that just continuously resets the state of the photodiodes to an unexposed state. At the end of exposure, the charge is transferred from the photodiodes into storage capacitors that hold the charge during sampling and readout. Therefore, the end of exposure must be concurrent with the start of the frame readout and only one frame can be held in the storage nodes at a time.

Do the vertical bands and the increased noise level issues persist after performing a black calibration? Note that changing the framerate will cause a change in frame timing that may invalidate the black calibration. In particular, framerates above 1053fps at 1280x1024 will need a different black calibration from framerates below 1053fps.

As for the horizontal lines; There is a horizontal artifact that appears in the raw image that corresponds to timing of where the shutter signal changes relative to the frame readout. The line of the image where this occurs is normally corrected by the black calibration. However, if the shutter is changed after black calibration then the calibration data will no longer correct for this artifact. The result is that you will see one or two horizontal lines on the image that will persist until a new black calibration is performed. This issue has existed in all previous software releases of the Chronos.

Another possible cause of horizontal lines that we are aware of when changing the shutter from the main window. If the shutter is changed in the middle of a frame it can result in a change in brightness partway through the image and this appears as bright flashes while changing shutter. However the issue should not persist for longer than a single frame.

Thanks for the testing and feedback everyone. I have updated this thread with an updated build of the beta software. Please see the first post for a link to the installer package. As a brief description of what has changed since the beta-1 backage:

Notable Features:
 - Reverted to two-point (linear) gain correction. After further testing the 3-point correction just seems to cause problems at the more aggressive gain settings.

 - Add a watchdog to reboot the camera in case of power-on boot failure.

Fixed Bugs:
 - Memory leak in the M3 video coprocessor which could lead to a crash after lots of H.264 encoding.
 - Ignore video which was recorded during black calibration.
 - Changes to exposure may be overwritten during black calibration.

NiNeff is correct, the image sensor digitizes an entire row at once and then reads it out 16-pixels at a time to the FPGA. While the first row is being read out to the FPGA, the second row of the image can then be digitized. The time that it takes to digitize a row can be adjusted by playing with the timing parameters of the image sensor but reducing the time allowed for this operation causes a loss of image quality.

The fastest framerate at any resolution is achieved when the row readout time is equal to the row digitization time, so that we minimize the time that the image sensor is idle. And the best quality is achieved when the row readout time is long enough to allow for the maximum digitization timing (approximately 922us per row).

On the 0.3.1 release of the Chronos 1.4, the fastest row digitization time is approximately 255us, which is equal to the time it takes to read out 336 pixels. This is why there is no performance benefit to reducing the horizontal resolution below 336 pixels. On the 0.3.2 release we have managed to reduce this time to 244us, which is why we now list 320x96 as the minimum resolution for that release.

Would you be able to share a screenshot of the Trigger I/O Settings window to show how you have the triggers configured? That might help us in trying to reproduce the problem you're seeing.

When you were using the v0.3.2 software update, did the issue occur at full-frame (1280x1024) and low gain, or did this banding appear only at the higher gains and/or smaller frame sizes? There have been reported problems at high gains using the new black calibration routines on v0.3.2 that I am presently working on.

To completely revert from v0.3.2 back to v0.3.1, you will also need to restore your factory calibration (in particular, the /opt/camera/cal/lux1310Offsets*.bin files will have been overwritten by the v0.3.2-beta software).

Regarding the issue with the power button and 'no batt' indication, I will have to try out reverting a camera from v0.3.2 to v0.3.1 and investigate the issue further. It is likely there are some files that may need to be deleted from the SD card to revert from v0.3.2 to v0.3.1 after the changes to the power controller for the automated power-on and power-off features.

Chronos User Discussion / Re: Maze artifact with 1.4
« on: June 22, 2019, 07:48:16 PM »
This is a known issue in versions v0.3.0 and earlier, and it is caused by the FPGA sometimes loosing the first pixel of a frame when shooting in 12-bit raw mode. The result is that the whole image gets offset relative to its bayer battern resulting in demosaic artifacts and color corruption. There was a discussion about the changes to 12-bit raw mode in the v0.3.1 beta software thread, which you can read here.

As part of the resolution of this issue, the bit packing order also changed between v0.3.0 and v0.3.1, so if you are using custom software to convert the 12-bit raw files you will also need to account for that change after updating the software. However, I do recommend using CinemaDNG for raw shooting as it requires fewer tools to process in Adobe Premier or Davinci Resolve.

Software Dev / Re: Chronos V0.3.2 Beta
« on: June 10, 2019, 12:10:00 PM »
Thank you so much, that does clearly demonstrate an issue with the new calibration routines when operating at high gains. I've been able to reproduce the problem and I'll be looking into it.

Software Dev / Re: Chronos V0.3.2 Beta
« on: June 08, 2019, 11:07:16 AM »
Can you attach some images to show us what the banding looks like at higher gains and framerates? Does the banding appear to change either for better or for worse after attempting a black cal at those settings?

Software Dev / Re: Chronos V0.3.2 Beta
« on: June 07, 2019, 03:19:30 PM »
Because this update includes some major changes to the calibration routines of the camera, for the best results we recommend re-generating your factory calibration after applying the update. You can do this by navigating to the factory screen and tapping the "Black Calibrate All Resolutions" button.

This procedure should be performed only once the camera has warmed up to its normal operating temperature, and the lens or body cap is in place.

In this release we are making changes to improve the camera's image quality by addressing the vertical banding issue that some users have reported and adding some new features to the power controller to make unattended operation of the camera a little easier.

Note that this update will affect your camera's factory calibration, you should back up your factory calibration before applying this update if case you have to revert back to v0.3.1 at a later time.

   ++                                  ++
   |     Chronos V0.3.2 Changelog       |
   ++                                  ++

Notable Changes:
  • Automatic ADC calibration during black calibration, which should reduce column banding across a wider temperature range.
  • Add a storage tab to the util menu to view, eject and format the attached storage devices.
  • Speed boost at most resolutions, with a top speed of 1069fps at 1280x1024, and 40420fps at 320x96.
  • Configurable automated power-on and off depending on the AC adaptor status.

  • Factory black calibration is now user accessible from the Factory tab of the util window.
  • The software update button has been moved to the storage tab of the util window.
  • Shipping mode to disable power-on by battery until an AC adaptor is attached.
  • Add a watchdog to reboot the camera in case of power-on boot failure.

Fixed Bugs:
  • Memory leak in the M3 video coprocessor which could lead to a crash after lots of H.264 encoding.
  • Ignore video which was recorded during black calibration.
  • Changes to exposure may be overwritten during black calibration.

Known Issues:
  • After applying this update, software versions v0.3.1 and earlier may no longer be able to receive battery data or utilize the power button.

Updating Your Camera:
  • Extract the .zip file into the root directory of a FAT32 formatted USB drive.
  • Turn on your camera and insert the USB drive.
  • From the main window, tap the Util button to open the utility window.
  • As a precaution, tap the Backup Calibration Data button on the utility window before starting the update.
  • When the backup is completed, a pop-up window will be displayed.
  • Tap the Done button to close the pop-up window.
  • From the utility window, tap the Apply Software Update button to begin the software update.
  • A warning message will be displayed, tap the Yes button to confirm and begin the update.
  • During the update, the screen will go blank and an Applying Update message will be displayed.
  • After approximately 60 seconds, the update will be complete and the camera will restart.

Chronos User Discussion / Re: Segmented recording problem
« on: June 07, 2019, 02:37:17 PM »
I've often found that the last segment when in segmented recording mode is effectively not usable and this is just due to the way that the camera operates.

When you start recording in segmented mode the video memory is divided into segments and the camera starts saving frames into the first segment. At each application of the trigger signal, the camera starts saving frames into the next segment. When the camera is saving frames to the final segment and it receives a trigger event it loops around and begins overwriting the first segment again. This process continues until you exit recording mode using the red button on the top of the camera, or the "Stop" button.

To summarize, the sequence of events is something like this:
  • Press the recording button to begin recording, the camera is now saving frames into segment 1.
  • Generate a trigger on the BNC port, the camera terminates segment 1 and is now saving to segment 2.
  • Generate a trigger on the BNC port, the camera terminates segment 2 and is now saving to segment 3.
  • Generate a trigger on the BNC port, the camera terminates segment 3 and is now saving to segment 4.
  • Generate a trigger on the BNC port, the camera terminates segment 4 and is now saving to segment 1, which overwrites the first thing we recorded.
  • Press the recording button to exit recording mode, the camera terminates segment 1.

As a workaround, you should be able to use the BNC trigger three times for the first three segments and then use the red trigger button to terminate the fourth segment.

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