The MP4 from an action camera is on the card, but the player refuses it or shows only part of the recording. Do not start by formatting the card or doing another test recording. First protect the original content and determine whether you are dealing with a problem with one specific video, a missing recording, or an unreadable card.
For some models, GoPro describes a built-in file repair after an incomplete save. The documented example in this article is the HERO9 Black, not automatically every generation or firmware. An unplayable MP4 alone also does not prove that a power failure was the cause: it may be a different recording or playback error.
The file exists — that does not yet mean a complete recording
The file name, date, and non-zero size are useful facts, not confirmation that the video finished saving correctly. After an interrupted save, the camera may need to repair the file. But a player’s error message alone cannot tell you whether all video and audio parts are available.
So document the exact symptom. Is a single file failing to play, or all of them? Do other videos from the same card play in the same player? Have you confirmed that this player supports the given recording type? These questions belong to assessing the copy, not to overwriting the original.
Do not create a new sample on the same card just to get a comparison video. If you need to test the camera, use another suitable card — and only once the original content is protected and the procedure is approved. The original recording must not be sacrificed to diagnosing the device.
Distinguish three different situations
| Observation | What is being assessed | First boundary |
|---|---|---|
| The MP4 is accessible but won’t play | The file, playback support, and recording completion | Work on a copy |
| The required file is missing | Availability of the original recording and card content | Do not record or format |
| The card disappears or reads end with errors | Medium stability and method of content retrieval | Stop ordinary home attempts |
A missing file will not be fixed by a tool just because you point it at an empty path. An unreadable card, in turn, is not a situation where it makes sense to first try several different players. These branches require different input and a different follow-up procedure.
An ordinary dead battery does not by itself mean the video must have been damaged. For handover, it is useful to state the circumstances — not to present them as a proven cause. Similarly, a long copy time alone does not prove a fault; specific errors and the medium’s behavior are what count.
Device not loading or reporting errors? Stop trying anything else.
What not to try any more:
- do not keep powering the device on or reconnecting it,
- do not run data recovery, repair or formatting tools on the failing media,
- do not open or take apart the device or the card.
How it works with us and what it costs: data recovery.
For standard recovery, the initial analysis may be free. Non-standard work (special data format, database, firmware, atypical problem) may cost 1 210 Kč including VAT (1 000 Kč excluding VAT); we tell you in advance. NONSTOP line 775 556 063.
How to protect the original
Stop further recording on this card. Power the camera off normally and remove the card only once the device is no longer writing to it. Do not put the original back into the camera for another automatic repair attempt before the content is protected.
Keep the card in a case and label which device it came from. Do not format, rename files, or perform file system repair writes. Installing a tool on your computer is not in itself work on the card, but you need to know where it writes and how it behaves; recovered files must not be saved back to the original medium.
The Lock switch on some SD adapters is not a universal guarantee of microSD write protection. Whether it is honored depends on the reader. If you need documented write protection for the original, the reading method must be chosen with appropriate equipment and procedure — not just by sliding a plastic switch.
A healthy, readable card: copy first
If the card remains stably accessible and reading proceeds without errors, copy its available files and directory structure to other healthy storage. Keep related files and original names too. Do not cherry-pick only the items that seem important for a player at first glance.
Verify that the copy actually exists and that you are working at the destination. Separate an untouched copy from a further working copy for tests. A regular file copy is not a bit-for-bit image of the whole card and may not preserve everything needed to assess a missing or deleted recording. If that is what you are dealing with, agree on proper medium acquisition before further experiments.
On the working copy, verify playback in an environment that supports the given recording type. Partial playback only proves that the played portion is available — not that the rest of the video is definitely intact, or that the problem lies solely in the container. Write down the exact error message and where playback stops.
If reading errors, disconnections, or a format prompt appear, end this branch. Repeated passes are not a substitute for proper content retrieval from an unstable card.
What File Repair in the camera means
The HERO9 Black manual describes a repair attempt when a file was not saved completely. It is a feature of one specific documented model. It cannot be promised that the whole clip, audio, or all frames will be recovered.
Because the repair modifies a file on the medium, it is not a read-only check for a single original. If it is to be used, the original content must first be protected and it must be verified that the model and card state match its documentation. With a one-of-a-kind recording or a failed copy, do not push the procedure forward based solely on the word „Repair."
If the repair already ran automatically before you noticed the problem, note that down. Do not repeat it without reason and do not judge the result merely by the error icon disappearing. You need to play back and substantively check the required parts of the recovered recording.
What to hand over to a specialist
Prepare the original card, an available untouched copy, and a description of how it was made. State the camera model, known recording settings, the circumstances of the interruption, the file name, and the player’s error message. Add a list of writes and repairs, including any automatic File Repair, formatting, or further recording.
Mark which parts of the recording matter and what you managed to play. The recording may contain personal data or protected content; do not send it to an unverified public video repair service. Agree on the handover method and work with the content with the authorized owner.
Frequently Asked Questions
Will renaming the MP4 file extension to MOV fix the video?
Renaming alone cannot complete missing content or file structure. Do not rename the original for such an experiment; any tests belong on a separate copy.
Should I format the card first?
No, if you need the original recording on it. Formatting alters the medium; it is not a safe way to retrieve its content. Further recording can also overwrite the data you are looking for.
Does every dead battery destroy the video?
That cannot be concluded. Document the actual circumstances and the available result. The battery state alone does not prove the cause of an unplayable file.
Should I let the in-camera repair run before backing up?
With a single irreplaceable original, this is not a safe starting point. Protect the content first and verify the specific model’s procedure; a repair is not just a read operation.
Is sending just the damaged MP4 enough for a specialist?
Not necessarily. Related files or the content of the original card may be needed for assessment. Agree on the scope of handover and keep the original, even if you already have a copy of the MP4.
If the copy keeps failing or the recording remains unplayable, describe the state of the card and camera to ITHOPE. Protecting the original gives further work a more reliable foundation; it is not, however, a promise that missing video parts can be recovered.
Sources and limits of the procedure
Documentation verified on 7 October 2026. For a different camera model or firmware version, verify the corresponding manufacturer procedure.
Where to find us
ITHOPE is a company based in Brno, Czechia: we do data recovery from disks, RAID and NAS, PC and laptop service and IT for business, all in our own lab at Viniční 3587/216, 615 00 Brno.
Phone +420 775 556 063 (24/7 line). You can bring the device in person, or send it by courier (Zásilkovna, PPL).