Action cameras and drones write a second, much smaller copy of everything they record. GoPro names them with an .LRV and .THM extension, and the DJI equivalent is an .LRF file. If you need to recover lrv files because the originals are gone, knowing what the proxies contain is the difference between a usable rescue and a wasted afternoon.
The first thing to do is not to look for the proxies at all, but at the original. Extraction is what you do after full-quality recovery has failed, not instead of it. The recovery workflow for GoPro HERO footage starts from the card and works upward, and the proxies are a separate, easier target you can always come back to.
What .LRV and .THM files actually are
Every chapter of video produces a small family of files that share the same clip number and differ only in their letter prefix. The main file is the full-resolution recording. Alongside it sit a low-resolution proxy and a single-frame thumbnail.
| File | What it contains | Typical dimensions | Notes |
|---|---|---|---|
| Main video | Full-resolution recording | 1920×1080 up to 5.3K | The file you actually wanted |
| .LRV proxy | Low-bitrate MP4 of the same content | 480×270 on earlier bodies, 640×360 on later ones | Complete MP4 with its own index and a reduced audio track |
| .THM thumbnail | A single JPEG frame | Around 160×120 | A JPEG with an unconventional extension |
| .LRF proxy (DJI) | Low-bitrate MP4 | Typically 960×540 | Accompanied by an .SRT telemetry file |
| .insv (360 bodies) | One file per lens | Full resolution | A container difference, not a format change |
Two details make the proxies more useful than their reputation suggests. The .THM file is a JPEG, so renaming it to .jpg opens it in any viewer without conversion. The .LRV file is an MP4, so renaming it to .mp4 opens it in most players that refuse the original extension. Neither rename changes a byte of the content.
Why the proxy frequently outlives the original
The proxy is roughly a tenth the size of the original, so it reaches the card and finishes flushing far sooner. When a battery fails, the camera is usually waiting on the main file, whose index covers several gigabytes of frames and must be written last; that index is what will not fit into the remaining seconds of power. The proxy’s index covers a few hundred megabytes and was committed while the recording was still healthy.
The consequence is counterintuitive in a useful way: the proxy is often structurally healthier than the original. A recovered original that will not play is missing its index and needs repair. A recovered proxy is a complete, correctly indexed MP4 that plays immediately, because it was finished long before the accident. The low-resolution file is not the damaged one.
The second counterintuitive point concerns the thumbnail, and it cuts the other way. A .THM file proves the clip started, not that it finished. The camera writes the thumbnail when the recording opens, as part of creating the file family, so an intact thumbnail is entirely compatible with a video that stops after ten seconds. Where a missing chapter is the problem rather than a missing file, the mechanics of chapter boundaries explain why the last chapter most often breaks and why its proxies may be the only survivors.
Recovering the proxy files from the card
The proxies follow the same recovery rules as anything else on flash media, with one advantage: they are small, so they are more likely to have survived a partial overwrite than the multi-gigabyte original beside them.
If the card was quick-formatted or the folder structure is intact but files have disappeared, a standard scan will find the proxies alongside the originals. If the directory entries are gone entirely, carving is the route, because MP4 files are found reliably by signature. When a scan returns a mixed pile of files, separate the proxies from the originals by resolution rather than by name, since a carved file has no name:
“ for f in *.mp4; do echo -n "$f "; ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=p=0 "$f"; done “
Anything reporting 480×270, 640×360, or 960×540 is a proxy. To make the files openable in the first place:
“ Get-ChildItem *.LRV | Rename-Item -NewName { $_.Name -replace '\.LRV$', '.mp4' } “
Rename copies rather than the only copies you have. The extension is the only thing standing between a proxy and a player, and a careless bulk rename across a mixed folder makes a set of originals harder to identify later.
The realistic quality ceiling
The proxies are not slightly compressed versions of your footage. The difference is measured in single-digit percentages of pixel count, and that number is the honest answer to what a proxy can be used for.
| Proxy | Pixel count | Against 4K UHD | Practical meaning |
|---|---|---|---|
| 480×270 | 129,600 | About 1.6% | Phone-screen review; visibly soft on any monitor |
| 640×360 | 230,400 | About 2.8% | Screenshot-quality evidence; poor for detail |
| 960×540 (DJI .LRF) | 518,400 | About 6.3% | The best of the proxy class; survives modest upscaling |
| 160×120 (.THM) | 19,200 | About 0.23% | Identification only: the frame existed, and little more |
Two ceilings apply on top of resolution. Heavy compression means the proxy smears on motion, and the effect is worst exactly when you want detail most: a fast pan, a rider crossing frame, water spray. And the color information is already reduced and tone-mapped, so grading latitude is close to zero.
Upscaling changes none of this. Enlarging 480×270 to 1920×1080 is a four-times linear interpolation that adds no detail, and an AI upscaler asked to do the same job produces a clean-looking frame by inventing plausible texture. For a social clip that trade can be acceptable. For anything that makes a factual claim, an upscaled proxy is a misrepresentation, and the unaltered low-resolution file is the more defensible artifact to keep.
What a proxy is genuinely good for
- Client confirmation and editing reference. Proving what was shot is often the entire commercial question when the original is lost, and continuity checks and shot lists work fine at proxy resolution.
- Insurance and incident documentation. A continuous, time-stamped record of an event is valuable regardless of resolution, and this is where keeping the file unaltered matters most.
- Recovering the audio. Even at reduced bitrate, a proxy’s audio track often carries usable dialogue or ambience that can be married to replacement picture.
Making a proxy into something you can hand over
The goal is to convert the proxy into a normal, well-behaved file at a standard size without pretending it is more than it is. A moderate upscale plus light sharpening produces something acceptable on a phone:
“ ffmpeg -i clip_lrv.mp4 -vf "scale=1920:1080:flags=lanczos,unsharp=5:5:0.6" -c:v libx264 -preset slow -crf 18 -c:a aac -b:a 160k deliverable.mp4 “
If you recovered proxies for a whole chaptered recording, join them in clip order in a single pass without re-encoding first, so you can judge the result before committing to any processing:
“ ffmpeg -f concat -safe 0 -i list.txt -c copy full_proxy.mp4 “
Then verify before it leaves your hands. Confirm the duration matches what you expect, check that audio is present, and play the file end to end rather than trusting a thumbnail. The verification routine for recovered files covers the checks worth running on any salvaged footage.
The photo side of the same problem has an equivalent technique: a damaged RAW file usually still contains a full-resolution JPEG preview, and the guide to extracting that preview walks through it with the same command-line tools.
If you are on Windows and the card is still detected by a computer, a purpose-built tool such as XRecovery (xappset.com) can scan SD, microSD, and other memory cards for deleted or formatted photos and videos, proxies included. The usual boundary applies: footage that has not been overwritten comes back in full, a recovered clip that will not play can often be made playable by re-encoding it, and footage that has been overwritten cannot be brought back. Stop writing to the card, and save recovered files to a different drive.
For the wider picture of what these cameras store and how their storage fails, the drone and action camera recovery overview puts the proxy files in context with the main recordings. If the footage came off a drone, the DJI-specific recovery path covers the .LRF and .SRT companions and the internal storage variants that behave differently from a removable card.
Frequently Asked Questions
Can I play an .LRV file directly?
Usually yes, after renaming it to .mp4. An .LRV is a complete MP4 container with its own index and reduced video and audio streams. Players that refuse it are reacting to the extension rather than the file, though a few older tools reject the internal brand identifier the camera writes.
Is an .LRV file good enough to deliver to a client?
Only with the client’s knowledge. At roughly 480×270 or 640×360 it is fine for confirmation, review, and reference, and below the minimum for broadcast, cinema, print, or any large display. Say what it is before you send it, and the file is usually received as a rescue.
Should I delete the .LRV files to save card space?
No. They cost a fraction of the main file’s space and they are your cheapest insurance against a failure that leaves the original unplayable. Leaving them in place has rescued many shoots.
Will recovery software find my .LRV files after a format?
Yes. A quick format clears the directory structure rather than the data, and proxies are small enough that they are less likely to have been overwritten than the originals beside them. Scan the card itself rather than a folder, and identify results by resolution rather than filename.