The strangest files on a drone card are usually the most valuable ones. Drone video file formats are dominated by MP4 in practice, but a modern flight card also carries .LRV proxies, .THM thumbnails, .GPR or .DNG stills, and, on 360 cameras, .insv originals that are not video as most software understands it. Two of those look like disposable clutter and behave like insurance: the low-resolution proxy and the thumbnail are frequently the only complete record of a clip that never finished recording. Do not delete them when you back up a card.
The file types you will actually find on a flight card
| Extension | What it is | Written by | Recovery value |
|---|---|---|---|
.MP4 | The deliverable video, H.264 or H.265 in an MP4 container | All drones and action cameras | Primary target; unplayable copies are usually repairable |
.LRV | Low-bitrate proxy video in a standard MP4 container | GoPro, DJI, Insta360 | High: a playable version of the same clip |
.THM | Small JPEG thumbnail | GoPro and others | Low to medium: proves a file existed, identifies content |
.GPR | GoPro RAW still, based on the DNG specification | GoPro HERO cameras | High: contains a full-size embedded preview |
.DNG | DJI RAW still for photo modes | DJI, some action cameras | High: public specification, tolerant of damage |
.insv | Insta360 dual-fisheye original, two streams in one file | Insta360 X and ONE series | High: the only unstitched source |
.insp | Insta360 stitched export | Insta360 Studio | Medium: a rendered output, not the source |
.SRT, .JSON | Telemetry and subtitle sidecars | DJI and others | Medium: flight data survives even if video does not |
.LUT | Color lookup table for flat profiles | GoPro | Low: affects appearance, not data |
GPR: GoPro’s RAW photo container
A .GPR file is a GoPro RAW photograph built on the DNG specification. It stores the sensor’s unprocessed data plus a large embedded JPEG preview, which is what the camera shows on its rear screen and what most file browsers display when you double-click the file.
That preview is the reason GPR files are worth recovering even when damaged. If a GPR is truncated during a transfer, the header and the preview usually survive, and tools such as ExifTool or a DNG-aware converter can extract a full-resolution JPEG from the wreckage. You lose the ability to redevelop the file — highlight recovery, white balance shifts, and the extra dynamic range all live in the RAW data — but you keep the photograph. GPR also needs a current editor: older versions of Lightroom and Photoshop treat the extension as unknown, and the RAW photo recovery notes cover what each editor can and cannot open.
The counterintuitive part is that GPR is more resilient than a JPEG in one specific way. Because the preview is a self-contained, complete JPEG near the start of the file, damage to the end of a GPR destroys the RAW data but leaves you a perfect, normally exposed image. The same damage at the end of a JPEG leaves you with the top half of a picture.
DNG: DJI stills and the sidecars that travel with them
DJI aircraft write .DNG for photo modes, sometimes alongside a matching JPEG when RAW+JPEG is enabled. DNG is a published, well-documented format, and that matters more than it sounds: because the structure is open, repair tools and metadata readers handle damaged DNG files far better than they handle proprietary RAW formats.
Three practical notes on DJI stills. First, a damaged DNG almost always retains its embedded preview and its thumbnail, so extracting those gives you something usable even when the RAW data is incomplete. Second, DJI writes sidecar files with the same base name, including .SRT subtitles that carry telemetry such as GPS position, altitude, and gimbal attitude. Losing the .SRT costs you data, not footage, so back it up alongside the video. Third, on dual-storage aircraft the same frame may exist on internal storage and on the card, and comparing the two is the fastest way to recover a file the card lost; the DJI recovery guide explains how internal and removable copies interact.
.insv: Insta360’s dual-fisheye originals
An .insv file is not a spherical video in the way most people assume. It is a container holding two fisheye streams, one per lens, plus the calibration and gyro metadata used to stitch them into a sphere later. Open an .insv in a normal player and you will see two distorted circular images side by side. That is not corruption; it is the unstitched source.
This matters for two reasons. First, .insv files must be processed in Insta360 Studio or an equivalent stitcher, and a file that “will not play” is often simply being opened in the wrong application. Second, when a file is recovered without its metadata intact, the two fisheye streams can still be separated and exported individually. You lose the stitched sphere and the keyframe direction data, but you keep two usable wide-angle views of the scene, which is usually the difference between a recovered shot and a lost one. The Insta360 recovery notes cover how the metadata blocks fail and what survives, and the dedicated guide to recovering .insv files walks through the file structure.
.insp files are the opposite case. They are already-stitched exports created by the desktop app, so they are ordinary equirectangular video and behave like any other MP4. If you have both, the .insv is the source and the .insp is a render.
.LRV and .THM: the low-resolution insurance policy
.LRV files are low-bitrate proxies that cameras write alongside the main recording so that phones and editing apps can scrub through footage quickly. They are standard MP4 files at reduced resolution, typically well under a megabyte per second, which is why a full card of proxies takes minutes rather than hours to copy.
.THM files are single JPEG thumbnails, usually 160 by 120 pixels or similar, and they exist so the camera can display a filmstrip without reading the whole file.
Both look like clutter, and both are worth more than they appear to be:
- An
.LRVis a playable video of the same content. When the main clip loses its index and will not open, the proxy still plays, and it covers the same duration at lower resolution. - On an interrupted recording, the proxy frequently contains the final seconds that the main file never finalized, because it is a separate file with its own, simpler write pattern.
- A
.THMproves that a file existed and what it contained, which is useful when a folder has been partly overwritten and you are trying to determine what was lost. - Both files are small enough to copy first from a card that is starting to fail.
The reason to preserve them is that they are written as independent files. Deleting proxies to save space on a shoot removes the cheapest fallback you have. Our guide to salvaging .LRV and .THM files covers what can be extracted from them and how far upscaling can take a proxy.
Chaptered files and how naming encodes their order
Drone and action cameras that record long sessions split the output into fixed-size chapters, and the file names carry the sequence. GoPro uses names such as GX010042.MP4, where the digits encode the file number and the chapter number; DJI uses sequential numbering with its own convention. The extension is ordinary MP4, but the recording is not one clip.
Two consequences follow. If you recover a folder of numbered fragments rather than a single file, you have chapters, not damage, and the job is concatenation in the right order — the mechanics of which are covered in the explanation of how GoPro chaptering works. And if one chapter of a set is missing, the recording has a hole in the middle even though every file you have plays correctly on its own.
Which files to copy first from a failing card
When a card is unstable, the order in which you copy determines how much you keep. Small files first is the rule, because a card that dies during a long read may never give you another chance.
- Sidecars and LUTs:
.SRT,.JSON,.LUT. Tiny, and they carry context you cannot recreate. - Stills:
.GPR,.DNG, and their companion JPEGs. - Proxies and thumbnails:
.LRV,.THM. - Main video:
.MP4chapter files, largest and slowest. - Anything on internal storage, which is usually untouched by whatever damaged the card.
For a card that is physically failing rather than logically damaged, image the whole card once and copy from the image instead of the original. That single pass preserves the smaller files as well as the large ones and limits how many times the failing controller is read. The drone and action camera recovery overview sets out the full sequence, and the storage media guide explains how microSD, eMMC internal storage, and SSD-based recording modules differ in how they fail.
What each format cannot do for you
It helps to be clear about the limits of these fallbacks.
| If the main file is… | The best fallback is | What you will not get back |
|---|---|---|
| Interrupted with no index | The .LRV proxy of the same clip | Full resolution and full bitrate |
| Truncated mid-file | The intact portion plus the .THM for identification | The missing duration |
| Overwritten by new recordings | Nothing; the clusters are gone | Everything in that region |
| Recovered but unplayable | Re-encoding the recovered stream | Nothing, if the data is complete |
An .insv missing its metadata | The separated fisheye streams | The stitched sphere and reframing data |
The last row of that table is the one people misread most often. A restored file that the camera or a phone cannot play is usually complete data wrapped around a missing index, and the fix is to rebuild the container rather than to recover again. Re-encoding a recovered clip produces a file that plays, which is a different outcome from recovering data that was never captured.
If you are on Windows and the card is still detected by a computer, a purpose-built recovery tool such as XRecovery (xappset.com) can scan SD, microSD, and other memory cards for deleted or formatted photos and videos. As with any recovery tool, stop writing to the card first and always save recovered files to a different drive. Data that has not been overwritten comes back in full; data that has been overwritten is beyond any tool’s reach.
Frequently Asked Questions
What is an .LRV file on a drone or action camera card?
It is a low-bitrate proxy video written alongside the main recording so phones and apps can preview footage quickly. It is a normal MP4 at reduced resolution, which means it plays, imports, and edits, and it often contains the last seconds of a recording that was interrupted before it finalized.
Can I delete .THM and .LRV files to free up space?
You can, but it removes your cheapest fallback. If the main file is later corrupted or interrupted, the proxy is a playable version of the same content and the thumbnail identifies what was lost. Copy them first from a card that is failing, then discard them if space demands it.
Why does my .insv file show two circular images instead of one sphere?
That is the unstitched source, not a broken file. An .insv holds two fisheye streams, one from each lens, and the stitching happens in Insta360 Studio using metadata stored in the file. Open it in the right application, and it becomes a normal 360 video.
Are .GPR and .DNG the same thing?
No. .GPR is GoPro’s RAW format and .DNG is Adobe’s published RAW specification, which DJI and other manufacturers also use. Both contain embedded previews, but DNG’s open structure makes damaged files easier for third-party tools to read and repair.