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Hi,
There are several possible cause for mis-synchronization.
What Kinovea version are you using ? (While we are at it, what Windows version ?)

Re: real time playback, do you mean that the speed slider decreases by itself or do you mean that at 100% speed the action is played in too slow/fast motion ?
When in dual playback, both speed slider should be locked (unless specified in the preferences).
Would you happen to be comparing a video taken with a high speed camera with a video taken with a normal camera ? If so, what is the capture framerate of the highspeed video ?

1. Add a perspective grid
2. Place its corners on the corners of a rectangular object visible in the scene and on the same plane as the plane that you want to make measurements on.
3. Right click the grid and use "Calibrate", enter the physical dimensions of the rectangle.

You can display the coordinate system with Image > Coordinate system.

Are you working with AVCHD / H.264 videos perhaps ? There are several issues with them that haven't been addressed yet.

Depending on the flavor of the encoder and the parameters used, they are more or less critical. Sometimes the working zone in/out points can't be set properly.

Upcoming in Kinovea
The configuration dialog now shows the various available stream formats (RGB24, MJPG, H264, etc.). On the C920, this allows the use of the streams that are compressed on-board by the camera, decreasing the bandwidth requirements.

For some specific stream formats (currently RGB24 and MJPG), the DirectShow's Intelligent Connect is not used and the plumbing is done manually. This has proven to be more reliable.

The vendor-specific exposure property from Logitech is now supported, allowing the configuration by 100µs increments instead of the default DirectShow property which is imprecise and badly supported by Logitech cameras. On the C920 the minimum value is 300µs.

A new capture pipeline has been implemented and integrated to streamline capture and recording.

For the MJPEG stream of the C920 and other cameras, the frames received are only decompressed for the preview. When recording they are directly pushed to the final file. The recording is given higher priority than the preview where a frame drop is not catastrophic. This greatly increases the throughput. I am able to record the full 1920x1080 @ 30 fps on my machine. We are still doing tests with Milan for the dual record scenario.

MJPEG is probably going to become the application perferred codec for output. It is simpler to implement and debug, mature JPEG libraries can be used, and its intraframe-only compression scheme makes it more suitable for frame-by-frame playback.

Thanks for the report.
Many cards from AVerMedia are advertised as "DirectShow compatible" which seems to be in contrast to other brands. Do you have any experience with these ?

Hi,

You can export the calibration parameters from within the calibration dialog using menu File > Save. The default directory is under "CameraCalibration" in the application data directory. Then from the second PC open a video, open the calibration dialog again and do File > Open and point it to the xml file.

To be clear, when you "Open" or "Save" it uses Kinovea format. When you "Import" it imports Agisoft Lens format. You can also directly reuse the Agisoft file and import it from the second PC.
You need to open/import it for each video.

The same file can be used for the same camera as long as the camera configuration doesn't change focal length, aspect ratio, etc.

For example on the PS3Eye there are two zoom positions by turning the ring.
On the GoPro depending on the configuration you can end up in Wide or Medium, 170° and 127° respectively I think. A different file is needed.

Technically each camera unit will have slightly different values. For example one of the computed parameters is the center of the lens relatively to the center of the sensor. It will not be exactly the same from one camera to the next.

That being said, the error introduced by these microscopic differences is probably less than the error of the calibration process itself, and less than the error introduced during coordinates digitization. So it may be fine to reuse a file created for a different camera unit unless you are already in an extremely controlled setting.

I'll gladly publish contributed calibration files on a dedicated page on the site so we can share them and experiment. Send them to joan at kinovea dot org and add details on the configuration with which they were created. If you validate that they also work at other configurations please mention it as well.

With regards to flipping, it's a known difficulty with DirectShow. Some formats needs to be flipped, others not.

Currently the code assumes the image is flipped (as it should for RGB24) and during the creation of the bitmap it inverts it. As it works on other machines I believe that assumption is correct but maybe there is another filter upstream that makes a faulty conversion…