File degradation - is it normal?

Question

Hard disks

There are two data carriers. One is an external hard drive (normal, not ssd) and there is a memory card in the phone. Not so long ago, I discovered that some video files on the hard drive have become much worse in quality (pixelation, noise, etc.). The files were there for three years. On a new memory card (less than a year old) today I found that some photos have turned into some kind of "stumps" (for example, only a third of the photo is there).
1. Is this normal? Or what am I doing wrong?
2. Files can somehow be restored to full?
3. How to protect yourself from this?
4. The standard Windows check does not find any errors on the media. Lying? Or are the media normal, and something wrong with the data?
Thank you!

Answer 1

With a hard drive , the description of the situation looks strange - usually, after all, when damaged, video files either begin to "crumble" (large pixels of random color, moving into stripes or a freezing picture), or break off during playback.
For starters, you can check the disk with R.tester . It can do both automatic diagnostics using built-in scripts and show you graphs of read speed / access time, which will show problem areas.
You can also make a full disk image for further work with it, the "correct" programs for creating images create a read error log.
With a memory card is more difficult. There the controller can be weird and you will not see what is happening behind it.
From simple verification options, you can do the following: insert a memory card into a computer and copy all available files from it (well, if some special program that also knows how to either verify data or monitor errors).
Then, well, if on another computer (for the purity of the experiment), do the same. If no other computer is available, then at least safely remove and re-insert the card before the second round. If there is another card reader, use it.
After that, take the file comparison program and compare the results file-by-file. If there are differences, this is a signal of a problem. Of course, you can also compare map images.
Rescuing these files yourself is likely to be difficult. The controller can easily give you different data without reporting any errors, i.e. software of the level available to you will not even try to reread broken files.
If the files on the memory card are important, consider contacting a specialized data recovery company and stop using the card until then. With direct soldering to the card and creating raw dumps of NAND memory, rereading is possible, because. the controller is no longer involved. about data recovery centers . PS
But the work will not be cheap, because. the card is clearly microSD, and this is a monolith. Just in case, here's a quick reminder
Stop using the standard disk check aka CHKDSK immediately. Check disk can easily shred your files so that no one can restore them later.

Answer 2

Files cannot be degraded. Disks can degrade, but the files simply stop being read. If the file is read (almost all image, video, music formats have a control code for verification), then 99.9999% that it is exactly the same as before.
Or you have something with the software with which you open these files.
Or, alternatively, some virus may have corrupted the files, but I do not know of a modern virus that would partially corrupt them. Crypters just crypt in their entirety.

Answer 3

These are two separate situations.
Degradation of files, as it is rightly said, does not happen.
If the memory card has begun to degrade, damage can lead to reading and writing defects. Checking for errors in this case may not show anything. At the same time, photos can be read partially, "to the middle", and so on. If they are in progressive format, the resolution may "degrade", because it is not possible to correctly read the end of the file with the smallest details.
On a magnetic disk with a video, something similar is possible. But video files often have features that allow you to partially restore the image when whole frames drop out.

Answer 4

But my problem is that the files are partially read. And I can't understand why this is happening. Moreover, the disk check finds no problems.

REMAP :

Reassigned sectors are bad blocks formed during the operation of the drive, which the drive marks as unused (usually they are placed in the G-List), and substitutes sectors from the unaddressed "reserve" field in their place. Thus, the capacity of the drive is not reduced, the drive continues to work.

When transferring data, it is possible to distort them.
Regarding recovery: now it's easier to download a file than to repair it. Most of the editors that match the file type can repair. The old VirtualDubMod did it.

Answer 5

Not so long ago, I discovered that some video files on the hard drive have become much worse in quality (pixelation, noise, etc.).

Maybe the computer does not have enough resources to fully play the video? I sometimes record video from the screen, so it seems to me that recently the videos have become worse in quality, perhaps even after the update against Meltdown / Specter, well, or I just haven't reinstalled Windows for a long time)

Answer 6

Look at the smart disk

Answer 7

Files are either readable or not, in graphic files, with reading errors, they can be partially displayed, especially often on memory cards - there are generally strange situations with them, so do not forget about backup. Noise and pixelation in images cannot appear over time.