Synchronization of video frames with sensor data in dataLogger

[Dima Bobby]

Hello, everyone,

I was given a task to achieve synchronization between video frames and other sensors' data such as accelerometer, gyro etc for a data logger application on Android. While the inertial sensors are synchronized between each other, they are not synchronized with the video frames. This issue was noticed in particular when working with dataLogger application from cellbots. Does anyone know what one can do for this? I have also gone the native level to go around inefficiencies of Java and implemented sensor polling in C and still no success. My tablet is Asus transformer TF700T.

Best regards,
Dima

[Alexandre Cabrit]

Is there any solution for your request ? Is it possible to synchronize video frame to sensor's datas ? I'd look at the source of datalogger and find that the battery timestamp is a date but others sensor's timestamp are a relative timer in nanoseconds... Is that correct ? 

[James Head-Mears]

I too would be very interested in finding if this is possible.

[Dima Bobby]

In the end, it was not possible to achieve a good enough synchronization better than 400 ms due to the fact that Android OS is not a real-time OS. I ended up doing some sort of a control movement involving shake of the device which I can detect in camera and in inertial sensors to remove this offset. It turned out however, that it changes over time. It was still somehow better than without doing any synchronization. 

We also found out that it depends on the particular device, Samsung S3 had much better synchronization in general.

[Jason Newton]

400ms sounds worse than expected, maybe as an outlier.  I am also working on a data acquisition task where I am stuck with android and am wondering if I can get a copy of your application to fool around with, Dima.  I'm used to doing this kind of thing in Linux but I am detesting it on Android - too much stuff in the way and java is not meant to do this.

It will definitely have a dependency on device - the implementation of the sensor backends all change very greatly by vendor/model in addition to memory and cpu performance altering outcomes... which can mean alot when you're in a rocky sucky environment for daq tasks like android.

-Jason

[spirit...@gmail.com]

RobotsAnywhere does this, here's a copy of the code - feel free to crib from it.

[w13738]

I am starting up a company doing Robot. Am interested to acquire cellbot related talent and existing technology in south bay area. If you are interested, please contact me.

On Oct 30, 2015 4:12 PM, "spirit...@gmail.com" <spirit...@gmail.com> wrote:

RobotsAnywhere does this, here's a copy of the code - feel free to crib from it.

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[spirit...@gmail.com]

We can definitely talk. You may have seen my recent work on Battlebots (I did the electronics and firware for Bronco). spirit...@gmail.com