On Sunday, I flew my Mavic Air, taking a video (4K) for the first half of the flight, followed by a couple of panoramas. All seemed normal-as the recording was running, I could see the elapsed time counting on the GO4 display, so I assumed it was recording. I had some videos on that SD card that were shot earlier in June, in addition to the 06/21/2020 videos. I then did my usual routine of copying all the changed files on the SD card to a folder on my PC for storage, and all seemed OK. To my surprise, there were no MP4 files from the Sunday flight!
However, I've found THM files on the SD card for DJI_0506, DJI_0507, and DJI_0508, but no corresponding MP4 files. This suggests that the MP4 files must have been created?? Aren't THM the "telemetry" files associated with videos? Their date/time stamps correspond with the time of the flights.
Based on some inputs from people on another forum, I put the microSD card back into the Mavic Air, and powered up. Took the RC and started recording a video, ran a few seconds, and stopped. All this time, I had the MA connected via USB to my Windows laptop. I saw that DJI_511 was recorded, and did play normally. Don't know what happened to the numbers between 505 (the last file that I have), and 511. There was also a 511 THM file. This process did NOT bring back any MP4 files.
So what’s the bottom line? I can’t figure out what happened here. I’m not happy about losing these video files (4K), but I at least want to understand how to prevent this from happening again.
THINK ABOUT THIS: DJI software is controlling all aspects of taking the video. The txt data file shows the video record start and stop, and the THM files' existence proves that MP4 files were created. Yet, neither those files, nor any intermediate files are to be found. These facts suggest that either:
* the DJI MA software had an error, or
* the SanDisk SD card had a failure
But, if the card had bad sectors, what are the chances that there were 3 write failures in a row?
Also, if the SD card had write failures, wouldn't you expect the DJI software to capture the write failures?
Doesn’t the fact that I was able to successfully record and play a video with that same SD card just yesterday, suggest that the card did not fail?
ADDITIONAL INFO
I looked at the flight record txt file with CSView, the camera data groups, and confirmed that recording was going on for the first half of the flight, followed by the panorama series. It would seem that the video file was correctly closed, since the recording was terminated normally, as opposed to letting the recording stop on its own when the drone shuts down.
THE SD CARD
The card is a 64G SanDisk Extreme PRO microSDXC Memory Card up to 100 MB/s, Class 10, U3, V30, A1 purchased in March 2018 from Amazon.com. It has never used anywhere other than this MA, and has served me with no problems. The filesystem is exFAT.
I don't know how many write cycles have been used, but for an estimate, I've copied everything that was ever recorded to this SD card, into a NAS and the total amount of data there is currently at 281GB across 1435 files - including plenty of multi GB video files. That would lead me to say that there have been an average of 5 writes (I know that's not exactly true), is a very low number of writes, relative to the card size. Also, the card is not reporting any errors.
I don't remember ever ejecting the SD card when the MA was ON. Certainly, I never removed it while video was being recorded. In this case, the video was shot on the first half of the flight, there were several minutes before the drone landed and the drone turned OFF. The card wasn't removed until I got home, which was well over an hour.
QUESTIONS
Is there any record in any file (log?), that could give a hint if, in fact, there ever were DJI_0506, 507 or 508 MP4 files created? Isn't it odd that THM files were written, but corresponding MP4 was not????
When I connected the PC and Mavic Air via USB, I got the following message:
===
Error checking (DJI-MAVIAIR(F
Repair this drive
We found errors on this drive. To prevent data loss, repair this drive now.
---> Repair drive
You won't be able to use the drive while Windows finds and repairs any errors. This might take a while, and you might need to restart your computer
====
I cancelled because I wasn't sure what it was going to do. The drive letter represents internal storage in the MA, and somehow I'm not sure my PC should be doing any writing to storage controlled by the Mavic Air. Any opinions? I've seen this before on occasion, and have ignored it.
I most certainly intend to run an SD card test software after this is all over. The only reason I haven't done so yet, is that we still don't know what happened here, and that card is the only thing that might hold the key.
However, I've found THM files on the SD card for DJI_0506, DJI_0507, and DJI_0508, but no corresponding MP4 files. This suggests that the MP4 files must have been created?? Aren't THM the "telemetry" files associated with videos? Their date/time stamps correspond with the time of the flights.
Based on some inputs from people on another forum, I put the microSD card back into the Mavic Air, and powered up. Took the RC and started recording a video, ran a few seconds, and stopped. All this time, I had the MA connected via USB to my Windows laptop. I saw that DJI_511 was recorded, and did play normally. Don't know what happened to the numbers between 505 (the last file that I have), and 511. There was also a 511 THM file. This process did NOT bring back any MP4 files.
So what’s the bottom line? I can’t figure out what happened here. I’m not happy about losing these video files (4K), but I at least want to understand how to prevent this from happening again.
THINK ABOUT THIS: DJI software is controlling all aspects of taking the video. The txt data file shows the video record start and stop, and the THM files' existence proves that MP4 files were created. Yet, neither those files, nor any intermediate files are to be found. These facts suggest that either:
* the DJI MA software had an error, or
* the SanDisk SD card had a failure
But, if the card had bad sectors, what are the chances that there were 3 write failures in a row?
Also, if the SD card had write failures, wouldn't you expect the DJI software to capture the write failures?
Doesn’t the fact that I was able to successfully record and play a video with that same SD card just yesterday, suggest that the card did not fail?
ADDITIONAL INFO
I looked at the flight record txt file with CSView, the camera data groups, and confirmed that recording was going on for the first half of the flight, followed by the panorama series. It would seem that the video file was correctly closed, since the recording was terminated normally, as opposed to letting the recording stop on its own when the drone shuts down.
THE SD CARD
The card is a 64G SanDisk Extreme PRO microSDXC Memory Card up to 100 MB/s, Class 10, U3, V30, A1 purchased in March 2018 from Amazon.com. It has never used anywhere other than this MA, and has served me with no problems. The filesystem is exFAT.
I don't know how many write cycles have been used, but for an estimate, I've copied everything that was ever recorded to this SD card, into a NAS and the total amount of data there is currently at 281GB across 1435 files - including plenty of multi GB video files. That would lead me to say that there have been an average of 5 writes (I know that's not exactly true), is a very low number of writes, relative to the card size. Also, the card is not reporting any errors.
I don't remember ever ejecting the SD card when the MA was ON. Certainly, I never removed it while video was being recorded. In this case, the video was shot on the first half of the flight, there were several minutes before the drone landed and the drone turned OFF. The card wasn't removed until I got home, which was well over an hour.
QUESTIONS
Is there any record in any file (log?), that could give a hint if, in fact, there ever were DJI_0506, 507 or 508 MP4 files created? Isn't it odd that THM files were written, but corresponding MP4 was not????
When I connected the PC and Mavic Air via USB, I got the following message:
===
Error checking (DJI-MAVIAIR(F
Repair this drive
We found errors on this drive. To prevent data loss, repair this drive now.
---> Repair drive
You won't be able to use the drive while Windows finds and repairs any errors. This might take a while, and you might need to restart your computer
====
I cancelled because I wasn't sure what it was going to do. The drive letter represents internal storage in the MA, and somehow I'm not sure my PC should be doing any writing to storage controlled by the Mavic Air. Any opinions? I've seen this before on occasion, and have ignored it.
I most certainly intend to run an SD card test software after this is all over. The only reason I haven't done so yet, is that we still don't know what happened here, and that card is the only thing that might hold the key.
