Same here ... Silly plastic lens 'hood': chronic fogging - K&F UV filter: problem solved.
Recent Job - Mini 3 Pro POOR pic and video quality
- Thread starter Dan AISCF
- Start date
I believe I have found the issue in this case.
After reformatting my SD Card in the Mini 3 Pro, I have not since had this issue. Last week I did another lake shoot, using our Air 2S, Autel Evo Lite+, and the Mini 3 Pro (as the shoot was 4 or 5 hours long). Upon examining the Mini 3 Pro footage, it was perfect (complete with 60fps and 120fps slo-mo).
I always run NDs on all of the drones, as it is always sunny when we shoot, so I don't think that was the initial issue. I'm thinking a bum card. In any case, on Prime day I loaded up on SD cards and might implement a rotation schedule for their use.
Again, thanks all for digging into this issue with me, your suggestions are appreciated.
After reformatting my SD Card in the Mini 3 Pro, I have not since had this issue. Last week I did another lake shoot, using our Air 2S, Autel Evo Lite+, and the Mini 3 Pro (as the shoot was 4 or 5 hours long). Upon examining the Mini 3 Pro footage, it was perfect (complete with 60fps and 120fps slo-mo).
I always run NDs on all of the drones, as it is always sunny when we shoot, so I don't think that was the initial issue. I'm thinking a bum card. In any case, on Prime day I loaded up on SD cards and might implement a rotation schedule for their use.
Again, thanks all for digging into this issue with me, your suggestions are appreciated.
NightFlightAlright
Well-Known Member
That is strange. On the one hand, 1s and 0s are 1s and 0s, and a digital fault is usually a completely munged/corrupted image.
But… it occurs to me that if the SD card was writing slowly that the firmware might reduce data rate on the fly…
One thing I still abide by is the no-delete/format-only rule.
Technically less required than back in the old days of CF cards, the rule always was to never delete individual files, only format the card completely. This was critical for CF cards with mechanical micro hard drives, and also for the earlier SD technologies…
I still practice this, tho it’s allegedly not such a requirement now… I wonder if the card had individual files removed prior to the problem? If so, that would indicate that in high performance situations the format-only rule is still best practice.
I totally agree with you on this. I would regularly delete files from all of our SD cards, as needed, then monthly or so reformat them. I began thinking there could have been an issue due to partial file deletions or something of that nature. Now, even for all of our plethora of Sony cameras, in addition to our 4 drones, I have implemented complete formats after each job has been backed up to our servers.
Thanks for your input, it's appreciated!
Droning on and on...
Well-Known Member
Describe in detail what you guys think happens on an SD card when you format it. To keep this simple, formatting in the drone.
Similarly, what you believe happens on the SD card when you delete a file.
The phrase, "partial file deletions" is what prompted me to ask.
Similarly, what you believe happens on the SD card when you delete a file.
The phrase, "partial file deletions" is what prompted me to ask.
I'm kind of thinking back to old-school tech days (been in IT and some form of tech since 95, still am) where you delete a file from a disk and there are "fragments" left over. Perhaps with this particular card and its usage, there were fragments or something left over that was causing issues, so a complete reformat totally removed the files/data, putting the SD card back into a completely error-free and usable state. Of course, this is just speculation. However, whatever it was, a complete format SEEMED to fix the immediate issue.
Droning on and on...
Well-Known Member
Okay, so there is some misunderstanding here.
When you delete a file, no data is erased or altered. The video or photo in its entirety is still there, and can be completely recovered until the card is written to again (and maybe even after that for a while).
File systems divide the storage space on an SD card into blocks of a fixed size, like say, 4096 bytes. There is a bitmap stored in part of the card the keeps track of which blocks are used, and which are free.
A file also has an entry in another table that keeps track of which blocks are part of which file. A file may not necessarily be contiguous in storage; it's blocks can be in different chunks of different length contiguous blocks, as few as 1, anywhere on the card. The File Allocation Table gives linear addressible, contiguous logical access to the file.
Finally, there's another table that maps file names to their entry in the FAT, keeps info on access permissions, and some other clerical stuff.
What Happens When You Delete a File: Simple – the entry in the directory is cleared, blocks allocated in the FAT cleared, and the blocks in the usage bitmap are marked free to be used for writing data as part of a different, existing file at some time in the future.
That's it. The data isn't touched.
What Happens When You Format: In this case, we're only considering quick format, as that's what the drone does, your smartphone, tablet, and the vast majority of formatting done on PCs. The directory is emptied, as is the FAT, and the block bitmap is zeroed (all blocks free). IOW, same as deleting all the files.
Unless you're doing a full format with a third party app, which takes a long time, zeroing all the data blocks, the vast majority of a 128GB card, like 94%, is completely untouched, unchanged, not "cleaned up", reset, etc. in any way from formatting.
When you delete a file, no data is erased or altered. The video or photo in its entirety is still there, and can be completely recovered until the card is written to again (and maybe even after that for a while).
File systems divide the storage space on an SD card into blocks of a fixed size, like say, 4096 bytes. There is a bitmap stored in part of the card the keeps track of which blocks are used, and which are free.
A file also has an entry in another table that keeps track of which blocks are part of which file. A file may not necessarily be contiguous in storage; it's blocks can be in different chunks of different length contiguous blocks, as few as 1, anywhere on the card. The File Allocation Table gives linear addressible, contiguous logical access to the file.
Finally, there's another table that maps file names to their entry in the FAT, keeps info on access permissions, and some other clerical stuff.
What Happens When You Delete a File: Simple – the entry in the directory is cleared, blocks allocated in the FAT cleared, and the blocks in the usage bitmap are marked free to be used for writing data as part of a different, existing file at some time in the future.
That's it. The data isn't touched.
What Happens When You Format: In this case, we're only considering quick format, as that's what the drone does, your smartphone, tablet, and the vast majority of formatting done on PCs. The directory is emptied, as is the FAT, and the block bitmap is zeroed (all blocks free). IOW, same as deleting all the files.
Unless you're doing a full format with a third party app, which takes a long time, zeroing all the data blocks, the vast majority of a 128GB card, like 94%, is completely untouched, unchanged, not "cleaned up", reset, etc. in any way from formatting.
Never use the 48mb mode ! its technically stiching images together! Always use the native 12mp shots! I don't know if DJI made these look better with updates but when I tried the 48mp images last year they looked terrible. all my shots are at 12mp on Instagram and my socials and they look great
THIS. Lol. I actually thought about this for some time after the shoot, as I NEVER shoot in 48mb mode. But, for this particular job, trying to get the photos to look almost as good as the ones out of the Air2S and Evo Lite+ I did. Never again.
It could be a combination of the SD Card and 48mb mode just made a random mess of the stills. Regarding the video that I think looks horrid only in a few clips, I'm thinking the SD reformat took care of it. I appreciate your thoughts on the matter as well!
NightFlightAlright
Well-Known Member
It’s simple. Formatting just replaces the directory & allocation table with an empty/fresh one, assuming the formatting is “quick” and for fat32, exfat, or f2fs.
The issue isn’t with “partial file deletion” and the issue is also not about the contiguosity of actual block of data, as the SD’s storage controller handles that, and this is where R/W speed is optimized for a particular speed.
An SD card optimized for high speed with large media files is going to have poorer performance for small files. But all of that is “behind the scenes” and out of our control.
The issue is with what is in our control, which is the file allocation table (FAT) and the file system itself, I.e. directory structure.
When we format an SD, all we are doing in most cases is replacing the FAT and file system directory (FAT/fs) with fresh empty ones.
If instead of formatting, we delete some files, we end up with free space in the FAT/fs of various sizes. Subsequent writes and or deletes of files causes the directory to become non-contiguous, and as the directory is itself a file, small bits of it must be added in small increments to map the files in the directory to the FAT etc.
Earlier I pointed out that SD cards that are optimized for large media files suffer with very small file performance. A directory, being a file, will incur speed penalties when it is chopped up and scattered into little chunks (the manner being determined by the OS/file system).
Best performance is a directory that is contiguous and being written to by appending the end. Performance suffers however when the directory itself is no longer contiguous, and write times are increased.
An intelligently designed streaming media recording system will increase compression to reduce data rates when the recording media is not keeping up. Increased compression results in lower quality.
For this reason, best practice is to format instead of delete, and get a fresh clean FAT/fs every time.
Droning on and on...
Well-Known Member
Well, it's actually stitching images together, really
Use what meets your needs and satisfies your standards. I harbor no criticism for pixel peepers. Wish they could understand others aren't as critical.
Droning on and on...
Well-Known Member
This is true, and good advice, if you leave files on the card. However if they're all deleted, the indexes, directory, and block allocation are all in the same state as after a format.
As you describe above, using a card over and over and "filling it up" with multiple files can result in worse and worse fragmentation, and the potential for performance degradation. This doesn't happen if you delete files as you remove them, which can be done with a single file move operation rather than a copy then delete.
The point is to empty the card before using it again. Formatting is a fine way to do it, no problem. My point here was simply to dispel the notion, that so many seem to have, that there's something magic about formatting... there isn't.
My process is to format when I have a dirty card with multiple files on it because it's a convenient way to delete everything. My Avata card gets formatted a lot, as it auto records on takeoff.
OTOH, I have camera drone cards I haven't formatted since the first time. They only get anything recorded when I want it, and I move everything off the card onto portable storage after flight, emptying it.
Never had a problem with any of these cards that haven't been formatted over and over.
NightFlightAlright
Well-Known Member
This is not universally true, and it depends on the file system and the operating system.
Some systems sprinkle drives with various invisible files. These files could end up anywhere, like speed bumps you don’t know about.
Some are added when you mount to some OSes, like the MacOS
.DS_Store not to mention others like .fseventsd, .spotlight-v100, .TemporaryItems, .TrashesMany of these are added when you mount the storage on a given OS.
Only formatting in-camera gets the card to the virgin state.
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