[DJI-log-discuss] Tiny 0x39 records with unknown contents

[Dennis Derichs]

You can download an example from
https://drive.google.com/file/d/17p8APYqMKX4sbjTx_UgG-5hrWJIZAKAO/view?usp=sharing
I also noticed that the details section of the file says that more than 4
hours of video have been recorded durgin the flight, which is obviously
wrong. That details field seems to have an alternate meaning, probably
related to the timelapse recording.

-Dennis

Am Di., 19. Jan. 2021 um 15:46 Uhr schrieb Ross Finlayson <
finlayson at live555.com>:

>
>
> > On Jan 19, 2021, at 8:16 PM, Dennis Derichs <harms.dennis at gmail.com>
> wrote:
> >
> > Using my Mavic Air 2 and the DJI Fly app on Android (file version 12) I
> recently took a timelapse video. Parsing the logs, I noticed a myriad of
> type 0x39 records that did not contain JPG data.
> […]
> > Your current code ignores the record length for type 0x39, skips the
> first two bytes of the payload and then checks for the SOI marker. If not
> found, it skips past the next 0xff. I propose a change to this code. If the
> payload begins with 00 00, an SOI marker and image data should be expected.
> Otherwise the record length should be observed and the payload unscrambled
> like that of any other record.
>
> Dennis,
>
> Thanks for the note.  Your suggestion sounds good.  However, could you
> please post an example of a “.txt” file that contains records like this, so
> I can use it to test the new code?  (If the file is large, then please
> upload it to a (publicly-accessible) web server, and send the URL instead.)
>
>
> Ross Finlayson
> Live Networks, Inc.
> http://www.live555.com/
>
>
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>
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