u/Ekmonks

My first attempt at making a panoramic image via image stitching. Four of the photos corrupted but thankfully all that meant is no front or very back of the boat. I asked AI to read the corrupted data and get the images back (Sorry). It gave me back images that were partially visible and partially corrupted.

Being curious I asked ChatGPT if I could use it to diagnose the actual cause of the corruption and it walked me through exporting all of the raw data of the floppy onto an .img file and then went to work reading it. It managed to fully recover all but one of the images I took, all of the previous images I took from before I formatted the floppy, and one partially overwritten from the session before that.

After a few hours and a few dead ends here is a timeline of events, inspired by the aircraft crash investigation shows I used to watch.

• The disk is formatted to shoot the SS United States →
• For some reason unknown to man MVC-001S.411 MVC-002S.411 MVC-003S.411 MVC-004S.411 MVC-005S.411, thumbnail files from the previous session, are not deleted. →
• During the first shot the camera saw these thumbnail files and chose the next nonconflicting number, 6. →

The root structure shows the new images being inserted around the surviving pieces of the previous file system:

MVC-006S.JPG

MVC-001S.411 ← old

MVC-006S.411

MVC-002S.411 ← old

MVC-007S.JPG

MVC-003S.411 ← old

MVC-007S.411

MVC-004S.411 ← old

MVC-008S.JPG

MVC-005S.411 ← old

• Image 006 through 011 are successfully recorded. 012 begins recording as a valid JPEG, but most of it's data will not be recovered. This is either an issue with the floppy reader or because I switched the camera from Record to Play while it was writing data. Switching between Record to Play while the camera was recording became my second leading theory to explain the corrupted images.
• Shooting ends and I put the floppy disk in my cheap Amazon USB floppy reader instead of my USB-B floppy reader that was taken from an old laptop (I've misplaced it)
• Windows creates SYSTEM VOLUME INFORMATION on the floppy disk at cluster 326, corresponding to physical sector 357. Inside it is an IndexerVolumeGuid file at cluster 327, physical sector 358, 76 bytes long.
• I copy the images to my computer. Windows asks the USB floppy drive for MVC-007.JPG, whos correct data starts at sector 99. Instead the drive returns data beginning at sector 171, a 72 sector discrepancy.

A quick aside to explain floppy disk storage. A 1.44MB floppy has 80 cylinders and two recording surfaces. Each cylinder is made of two tracks on the top and bottom side of the disk. These tracks contain sectors, 18 per track, 36 per cylinder, which each can hold 512 bytes of data. (See final photo)

• 72 Sectors is equal to exactly two cylinders, too precise to be random corruption. →
• Ergo, the USB floppy mechanism intermittently positioned itself two cylinders away from the requested location. →
• Photos 006, 009, and 011 are read correctly. 007, 008, and 010 are not. →
• Photo 012 copies 29,286 bytes with no JPEG start or end marker (FF D8 and FF D9). Instead it begins with 71 A0, which seems to be compressed image data. →
• 007 starts two cylinders too far forward in sector 171 instead of sector 99. It reads the latter part of photo 008 writing 20,480 bytes before reaching the beginning of photo 009, writing 10,156 bytes to the file to be known as MVC-007S.JPG. →
• Similar errors happen to 008 and 010 →
• Seeing that files have corrupted I make a pano with the uncorrupted images. →
• I try multiple websites to uncorrupt the broken .JPGs but they refuse the files. →
• I go to ChatGPT and send it the corrupted files in a zip, it manages to "reconstruct" the data based on the valid JPEG steams inside the malformed files. but unbeknownst to all parties the recovered photo data does not correspond to the file name. This will cause confusion. The JPEG inside MVC-010S.JPG is not photograph 10. →
• I notice the .411 files from the previous session that were not deleted and assume they have something to do with the corruption, ChatGPT agrees with this and asks for the extracted raw data of the disk. →
• Win32 Disk Imager could not see the USB floppy reader, but Powershell could open \\. \A: directly. A sector level read is initiated. →
• The sequential raw read stopped after 1,269,760 bytes/2,480 sectors. Subsequent spot checks showed sectors becoming inconsistently readable. At first the .img up to that point was treated as trustworthy. →
• Parsing the filesystem found the current 006–012 entries, the still-live old 001–005 .411s, and dozens of JPEG headers in old/unallocated data. →
• The scan produced 35 complete old JPEGs plus one partial. I recognized the 35 as the previous shooting session and the partial as an image from two sessions ago. →
• Because the .img showed a good 006–010, an apparently truncated 011 and old-looking data where 012 should be, ChatGPT concluded that the camera had failed while writing 011 and essentially failed before writing 012. This contradicted 011 being uncorrupted during the initial windows file explorer transfer. Therefore the raw image could not be an accurate representation of the original 011 write. →
• I uploaded all of the original windows explorer copies to compare byte by byte with the floppy disk data. →
• The +72-sector discovery points to the floppy reader as the culprit of the corruption, not the camera or it having a formatting error. →
• I get a snack because it's been 2 hours now. →
• It is discovered that bad 007 contained 009. Bad 008 contained 010. Bad 010 contained 012. →
• The good 011 and the accidentally shifted 010 both independently contained the same correct 011 tail. The raw image was the erroneous third read. 012 begins as a valid JPEG but is only partially recovered.

Conclusion: 006–011 were successfully recorded. 007/008/010 were corrupted during reading, not recording. 012 definitely began as a valid JPEG but remains only partially recovered. The exact reason the five old .411 files survived FORMAT remains unresolved.

In summary, the cheap no brand name made in China Amazon Floppy reader is indeed materially different than my older laptop floppy drive. I've read warnings about their unreliableness. I'm going to avoid using this Amazon one in the future.

Is ChatGPT better at this than a version of me who did a bunch of research and learned how to read the raw data and that FAT12 stuff? No. It is quicker, but made many mistakes I had to make it correct. Some of that could be sloppy prompting on my part, but also the AI making mistakes, for instance insisting the raw data of 011 was partially corrupted while 011 was not one of the files corrupted when initially transferred through the floppy reader. At the very least I've spent 4 hours learning things I didn't know before. ChatGPT gets really annoying after a while and I don't like the dance between transcribing it's report of what it did with it's insistence on how I should or shouldn't say it. All it's (sometimes contradictory) information came in an unclear order and it was a lot of work to get it all into a condensed and organized presentable form. It's like a deal with the devil to turn a multi-day project into a multi-hour one.

I recently bought an FD200 that came with 20 or so floppies. I'm going to see if I can extract all the deleted images from the raw data. I'm sure to many it was well known that deleting the data or formatting the data doesn't make it "disappear." I vaguely knew that to some extent. I'm interested now in using these findings as an artistic technique. I think it would be interesting to explore partially corrupting image data and combining the data of two photos in-camera.

Picked up for $5 at Goodwill and this thing definitely punches above it's weight. I like it's MPEG video recording. This is my first "quality" digicam that isn't a Sony Mavica floppy disk camera.

body text

low stakes mythology

North Carolina. Also I have a small grey spot that's appeared in all my photos, not sure what it is or what to do about it. Can the sensors get dead pixels like modern cinema cameras do?

It was 10:30 at night, wet, and I felt like something was watching me. I appreciate everyone's support on the last past, I worked hard on making that text on my laptop.

Put on the Silgo River Blues and listen to that while you look for the best experience.

I decided to visit the spot again, it had been heavy rains all day. I'll keep this up until I get bored of it I guess. (FD7)

FD7 ((Yellow Floppy Disk ) It was my Dad's floppy disk when he was my age))

None of my other cameras make stuff that makes me feel this strong of тоска