dashware

Dashware Assets

I have used Dashware for overlaying telemetry data on top of a video file. I include the reusable assets here:

• Project Template - place this in the projects directory (\Documents\DashWare Projects) and then rename the folder to whatever you want to call the project. When you open it in Dashware, it will prompt you to find the data.csv and video.MP4 files.
  • This project contains all you need Centauri data profile, Gauges, etc.

You can download the dashware software online or get the installer here.

Steps to Overlaying Telemetry on Onboard Footage

1. Convert the variable frame rate onboard footage to a constant frame rate using FFMPEG (see notes below)
2. Observe different in timing + duration between two "points" in the flight you can clearly see in both the telemetetry and the video.
3. The telemetry timing is correct. Comparing the video timing to it, you will see the video is either a little bit slower or faster. Do the math on what % the video needs to speed up or slow down by to match the telemetry.
4. In Premiere Pro, position the .avi file in a 1920x1080 sequence with the original file magnified 180% in the middle. And then speed up/slow down the duration by the % calculated above. Export that.
5. Dashware: sync up timing of telemetry over the video in Dashware and export.

Important Note About Timing

I noticed while recording on the DVR on my FPV monitor, I just wasn't able to get the telemetry Centauri logs synced with the video. And the desync appeared to be worse further into the video, as time goes on.

I believe this is because the DVR on the FPV monitor is of very poor quality and actually records slower than the passage of time, causing this issue. I went and compared the "armed" duration on the telemetry and the "armed" duration on the monitor-recorded video (just timestamps on the video):

• Duration of Armed in Telemetry: 268.956 seconds
• Duration of Armed in Video: 270.133

So, as we can see above, the video is longer than the actual telemetry! It is 0.44% longer! This can for-sure cause a desync issue!

So, in this scenario, the solution I used was to slow down the video just a tad so the arm begin and arm end times of the video match the telemetry data. We can do the math on this and se that to make this adjustment, I would have to stretch the video to 99.564165844% of its original time.

To do this, I calculated what the correct duration of the total clip should be, in seconds. Then, with that in mind, I calculated what the Minutes:Seconds:Frames timestamp should be in premiere pro (i.e. at 30 FPS). I calculated that, placed my sequence time there, and then used Premiere Pro's Rate Stretch Tool to "stretch" the video to end at that time exactly, with the difference being sped up/slowed down automatically!

Having an issue with syncing up telemetry over a FPV Monitor/Goggle DVR Footage? Here is the fix!

Using FFMPEG, "trim out" a clip of the flight you want to use. This will trim out the video, set it to a constant frame rate and do so in lossless quality:

ffmpeg -i onboard.AVI -ss 00:07:20 -to 00:11:00 -vf "fps=30" -q:v 1 flight6.avi

After this, in Premiere Pro, compare the total flight duration (duration while "armed") between the telemetry (recorded by Microcontroller) and the FPV video. More likely than not, the FPV video will be longer than the telemetry. I believe this is because the video recording is slow.

Calculate the time the video should end by doing some math (seen above). Use the rate tool in Premiere Pro (on the constant frame rate export!) to adjust the time length of the video to the target duration (to match the telemetry) and then position it in a widescreen format.