Owners of the action camera Xiaomi Yi 4K often face a mysterious situation: after active shooting on the memory card, files with the extension.sec instead of the usual.mp4. Instead of the expected video, the user sees an object that is not available for playback, which does not open in any standard video player, this causes panic, especially if the shooting was important and unique.
In fact, the appearance of such files does not always mean hardware failure or data loss..sec files in the context of Yi Technology devices are often encrypted or unfinished video streams that the security system or a recording failure did not manage to properly process. Understanding the nature of this data is the first step to its successful recovery.
There are several reasons why the camera decides to save the material in this format, which may be due to settings of the encoder H.265, interruption of recording due to battery discharge, or use of memory card that does not meet the requirements for writing speed.
The Nature of the SEC Format in the Yi Ecosystem
The SEC acronym for Yi camera files often stands for Secure or indicates a specific segmented container. The camera uses this format as temporary storage or as a result of a failure protection mechanism. If the recording process is interrupted suddenly, the system does not have time to close the file, adding the necessary headers and indexes characteristic of the MP4 container.
It’s important to understand that there are often whole video data inside the file, which simply lacks the right “packaging” that media players require to start playing. Xiaomi Yi 4K, with a powerful processor, records huge amounts of information, and the slightest delay in writing to the card can lead to the formation of a.sec archive.
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Use only U3 and higher memory cards to record video in 4K resolution to minimize the risk of.sec files due to low write speeds.
Sometimes these files are created specifically if the encryption function is enabled or if the camera is operating in a mode that requires authorization through the viewing application. However, in 90% of cases it is a “unwritten” video.
- 🎥.sec files can contain full video, but without the correct container header.
- ⚙️ The format often occurs when switching shooting modes or a sharp power outage.
- 🔒 In rare cases, the extension indicates enabled encryption in the application settings.
- 💾 The size of the.sec file usually coincides with the duration of the shooting, which indicates the availability of data.
The main reasons for the appearance of files with the extension.sec
The first and most common reason is to use an inappropriate memory card: Yi 4K camera records high bitrate video, especially in 4K 30fps or 1080p 120fps modes. If the card write speed falls below the required threshold, the buffer overflows and the system urgently completes the stream, keeping it raw.
The second reason is because of the codec settings: By default, the camera can use the efficient but resource-intensive H.265 codec (HEVC). Some firmware versions or third-party recovery programs mishandle H.265 streams when crashes, leaving them in.sec format. Switching to H.264 often solves the compatibility problem.
The third reason is software errors in the camera itself, or incorrect retrieval of the memory card, so if you pulled the card right after the recording stopped without waiting for the activity indicator to go out, the file system might not have time to update the file placement tables, and as a result, the computer operating system sees only the initial data segment.
⚠️ Warning: Never format a memory card inside a camera immediately after.sec files appear if you plan to restore them.
Also worth mentioning is the overheating of the device, which can heat up Yi 4K during long-term high-resolution shooting, leading to trotting and resetting of the recording buffer, and at such times, the formation of incorrect files becomes most likely.
Methods of renaming and converting files
The easiest way to do this, but it doesn't always work, is to try to manually rename it. Because the internal structure of the data often remains the same, sometimes it's enough to just change the file extension.
Select the file, press F2 (or select Rename in the context menu) and replace.sec with.mp4. The system will warn you of possible data corruption — agree. After that, try opening the file in a universal player, for example, VLC Media Player, which is less demanding of file headers than standard Windows players.
☑️ File compatibility check
If a simple renaming didn't work, it would require a deeper conversion, and there are specialized tools like Unsec or Yi4kparser that are built by enthusiasts specifically to work with Yi Technology cameras, and they can read raw data and repackage it into the correct container.
The process of using these utilities is usually as follows: you point the path to the.sec folder, select the target folder to save and start the process. The program analyzes the bit stream, finds the beginning and end of the video frame, and creates a new file with the correct structure.
| Method | Difficulty | Efficiency | Risk of data loss |
|---|---|---|---|
| Rename | Low. | Medium | Minimum |
| Specialty Utilities (Unsec) | Medium | Tall. | Low. |
| FFmpeg (console) | Tall. | Maximum | Medium. |
| Video editors | Medium | Low. | High-pitched |
For advanced users, the FFmpeg tool is available, and you can try to pull the right container onto the video stream by commanding you to copy the streams without transcoding. This keeps the quality and often saves files that other methods ignore.
Using specialized software for recovery
When standard methods fail, professional software comes to the rescue, programs like Digitus Yi 4K Fixer or universal video reenactors analyze the structure of the file bitwise, they look for signatures of the beginning of the video stream (often these are byte sequences characteristic of H.264 or H.265) and cut off the excess data.
One of the most popular free utilities is Yi4kparser, which works via the command line, which can scare off newcomers, but it gives you a great result: you need to download the executable file, put it in the folder with corrupted videos and run the corresponding command through the terminal.
yi4kparser.exe input_file.sec output_file.mp4This instructs program command takes the input file.sec and try to assemble it from a working.mp4. If the file was corrupted due to the lack of a final index, the program will try to recalculate it by scanning the entire video stream.
Where can I find recovery utilities?
There are also paid video recovery solutions that have a graphical interface, and they often have a preview function, which shows if it can recover a file before the payment process begins, which is convenient because it allows you to avoid spending money on hopeless cases.
Setup the camera to prevent the problem
To avoid.sec files in the future, you need to set the camera up correctly. First of all, check the settings of the video codec. Go to the camera menu (via the screen or app), select Settings → Video → Video Codec. Make sure you choose H.264. This codec is less efficient in size, but much more stable and compatible.
The second important step is to check the memory card. H2testw or F3 Low quality flash drives are often labeled as fast, but in practice do not withstand the flow of data. 4K-video, which leads to recording failures.
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Using the H.264 codec and V30/U3 memory cards is the best way to prevent.sec files from appearing in the Xiaomi Yi 4K camera.
It is also recommended to update the camera firmware regularly, and Yi Technology engineers periodically release patches to fix file system errors, and check the version from the Settings → About → Version menu.
Remember to end the session correctly. After the recording stops, wait 2-3 seconds until the indicator stops flashing before turning off the camera or removing the card.
Prevention and work with the file system
The memory card file system also plays a role. Yi 4K cameras work best with FAT32 file system for cards up to 32 GB and exFAT for larger cards. If the card is formatted in NTFS, the camera can behave unstablely.
It's recommended that you format the map inside the camera, not on the computer, and the camera creates the folder structure it needs and aligns the clusters in the way that is optimal for your controller, and do this periodically, especially after long shootings.
⚠️ Note: If.sec files are constantly appearing even on a new card, there may be a problem in the memory card slot or camera plume, in which case a diagnosis is required at the service center.
Watch the temperature of the device. If you shoot in hot weather or in direct sunlight, try to let the camera cool. Overheating is a hidden enemy of recording stability, which often leads to logical errors in files.
Backups are made regularly, even if the file is corrupted, having the original on the map increases the chances of recovery by specialists, and don't overwrite the map with new data until you make sure that the old files are saved and working.
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Buy a high-TBW (Total Bytes Written) memory card if you plan to shoot intensely in 4K. Conventional cards wear out quickly when you constantly overwrite large amounts of data.