Telemetry Overlay for Mavic (and other models) in After Effects

Khurrum · Apr 8, 2020

Hi 0Kajuna0,
I've done detailed analysis of your updated SRT Viewer with Mavic2Zoom. I cannot see my earlier conversations with you, maybe admin has deleted. Just to recall that I had shared DJI_0235.srt file with you and you did corrections in the SRTViewer application, as the speed and altitude gauge were not working correctly.

In this regard, plz check my attached pdf document of detailed analysis, srt file and flight record file csv (AirData) file.

plz consider my request, which I've mentioned in the end of pdf document.

Testing is shown in the following youtube video and its details are in the pdf file

0Kajuna0 · Apr 8, 2020

Hi @Khurrum ,

The main problem with accuracy comes from the fact that the SRT logs the drone produces do not have the necessary position accuracy. I added the smoothing options in order to average out the errors, but it is not a perfect solution as you can see. This has been brought up to DJI but I am not confident they will fix it. in order to read the most accurate values the system would have to read the data from the TXT logs, which is not possible at the moment (and I won't be able to implement that in the short term).

This is also what causes wrong max and min speeds.

Regarding altitude, most drones record it relative to ground level and many users want to use the value relative to sea level, so the program tries to compensate for that. You can disable this compensation with the Sea-level button:

The next update to the After Effects template will include an offset control in case you need to make additional corrections to the altitude. I expect to publish the update in a couple of weeks.

Khurrum · Apr 8, 2020

0Kajuna0 said:
Hi @Khurrum ,

The main problem with accuracy comes from the fact that the SRT logs the drone produces do not have the necessary position accuracy. I added the smoothing options in order to average out the errors, but it is not a perfect solution as you can see. This has been brought up to DJI but I am not confident they will fix it. in order to read the most accurate values the system would have to read the data from the TXT logs, which is not possible at the moment (and I won't be able to implement that in the short term).

This is also what causes wrong max and min speeds.

Regarding altitude, most drones record it relative to ground level and many users want to use the value relative to sea level, so the program tries to compensate for that. You can disable this compensation with the Sea-level button:

View attachment 98244

The next update to the After Effects template will include an offset control in case you need to make additional corrections to the altitude. I expect to publish the update in a couple of weeks.

Ok
Thank you

Khurrum · Apr 8, 2020

Is it possible for you to share remaining gauages, so that I can test them with Mavic 2 srt.?

You can add any time bound condition that they expire after a certain period

Thanks

Khurrum · Apr 10, 2020

Hi,
Can you plz explain, how this "smooth" parameter of SPEED Control works in After Effects. Its default value was 10. I set it as 100.

and what is its permissible min/max values.

0Kajuna0 · Apr 11, 2020

Smoothing averages every sample with the surrounding ones. If you select 10, every sample is the average of itself, 10 samples before it and 10 samples after it. SO 100 will have to analyse 201 samples for every frame

Khurrum · Apr 11, 2020

0Kajuna0 said:
Smoothing averages every sample with the surrounding ones. If you select 10, every sample is the average of itself, 10 samples before it and 10 samples after it. SO 100 will have to analyse 201 samples for every frame

Thanks

0Kajuna0 · May 9, 2020

Could anyone confirm if the Mavic Air 2 records telemetry data to the subtitles?

As it uses the same app as the Mavic Mini, I'm assuming it does, but would be cool to get a sample.

Thanks!

timmattison · May 22, 2020

I turned on video captions for my Mavic Air 2 today. I do get SRT files in the output directory. Someone further back in the thread commented that the coordinates are strange and I'm seeing the same thing. The coordinates appear to be relative to some location instead of normal absolute coordinates. One sample coordinate I'll share is this:

Latitude: 0.717896
Longitude: -1.287538

The actual coordinates should be more like 41.132441,-73.7710512.

Anyone know how to reliably convert these coordinates?

0Kajuna0 · May 22, 2020

timmattison said:
I turned on video captions for my Mavic Air 2 today. I do get SRT files in the output directory. Someone further back in the thread commented that the coordinates are strange and I'm seeing the same thing. The coordinates appear to be relative to some location instead of normal absolute coordinates. One sample coordinate I'll share is this:

Latitude: 0.717896
Longitude: -1.287538

The actual coordinates should be more like 41.132441,-73.7710512.

Anyone know how to reliably convert these coordinates?

Could you send me a full sample? I'll see what I can do. My email: [email protected]

timmattison · May 22, 2020

Sent, please keep us all posted. And thanks!

0Kajuna0 · May 22, 2020

Thanks Tim,

Did you move much while recording that video or did you just go up? Aside from the off values, if you did move, then the latitude and longitude values are either wrong or so low in precision as to not be usable (I was thinking they might need a multiplier to make sense, but the resulting values are too "round"). Other models record the home position to the SRT files, which would allow us to try and associate the lat/long values with the home point, but not this one. Usually the mp4 video files do contain a standalone coordinate (you can get it if you have ffmpeg on your computer, other apps might do that too). Anyway, the distance between the 0,0 point and 0.717896, -1.287538 (the first sample in your file) is more than 150km, so that does not make much sense.

I'm assuming they either encoded the coordinates in a new way, or there's a bug in the firmware (the coordinate system starting in a strange place, or where you last started the drone...?) that they will address at some point (as they have done with other models). They have never been very consistent with these SRT files. See the typo in "longtitude".

I'll keep an eye open for more info.

timmattison · May 22, 2020

0Kajuna0 said:
Thanks Tim,

Did you move much while recording that video or did you just go up? Aside from the off values, if you did move, then the latitude and longitude values are either wrong or so low in precision as to not be usable (I was thinking they might need a multiplier to make sense, but the resulting values are too "round"). Other models record the home position to the SRT files, which would allow us to try and associate the lat/long values with the home point, but not this one. Usually the mp4 video files do contain a standalone coordinate (you can get it if you have ffmpeg on your computer, other apps might do that too). Anyway, the distance between the 0,0 point and 0.717896, -1.287538 (the first sample in your file) is more than 150km, so that does not make much sense.

I'm assuming they either encoded the coordinates in a new way, or there's a bug in the firmware (the coordinate system starting in a strange place, or where you last started the drone...?) that they will address at some point (as they have done with other models). They have never been very consistent with these SRT files. See the typo in "longtitude".

I'll keep an eye open for more info.

I didn’t move much in that video. I just realized that I flew up and only went maybe 100 feet before recording a new video. Should I send you another track and the video to go with it so you can see it is really going somewhere?

0Kajuna0 · May 22, 2020

If you can, yes. That can help. If you just flew vertically, the coordinates might have usable units and just need an offset applied. If you need FTP details to upload the file, let me know.

Also, I know the problems in the SRT files of the Mavic 2 were fixed after people complained on the official forum. Not sure if that had anything to do, but if you're ok with that I would share a couple of lines of your file there to try and catch the attention of the moderators

0Kajuna0 · May 25, 2020

Ok, the Mavic Air 2 SRT files can be parsed now. Things will improve when DJI fix their data, but it's usable: DJI SRT Flight Data Viewer and Converter

volition · Aug 22, 2020

0Kajuna0 said:
Ok, the Mavic Air 2 SRT files can be parsed now. Things will improve when DJI fix their data, but it's usable: DJI SRT Flight Data Viewer and Converter

hi Kajuna,

I use your telemetry for GoPro on my Rc cars in after effects. Love it.

now I have a DJI Mavic air 2 and was wondering if there was an AE overlay and lo and behold it is yours!

so I was just reading your last few messages on the thread in regards to the MA2 so can you confirm your overlay and srt extraction works for MA2. Any special tricks? Or after turning on subtitles it’s pretty straight forward?

exciting to be able to use gauges I’m pretty familiar with.

0Kajuna0 · Aug 22, 2020

Hey @volition , glad to see you here!

Yes. I don't have an Air 2 but as far as I know it works well. Feel free to send me a sample SRT file privately if you want to see the results.