Lazaclip

Wedding or event video left an RSV file: what to do now

Updated 8 November 2026

The battery died during the vows, the card was pulled a second too early, or the camera froze in the middle of a speech. Instead of an .MP4, the Sony camera left a file ending in .RSV. At a wedding or a live event there is no second take. The good news: the footage is usually still in that file. This guide covers what to do on the day, what to try for free, and how to get a normal MP4 back.

On the day: stop the damage first

The most common way to lose an interrupted take for good is to keep shooting on the same card. So, as soon as you notice:

  • Swap the card and carry on with a fresh one. Label the old card and put it somewhere safe.
  • Don't record on that card again until the take is back. New recordings can be written over the space the interrupted take occupies.
  • Don't format the card, even if the camera asks you to.
  • Don't delete the .RSV, and don't try to fix it on site on a laptop that is about to run out of battery itself.

If the camera was recording to both card slots and only one card was pulled out, the other card may hold a finished .MP4 of the same take. After a dead battery, both cards usually hold an .RSV: keep both and copy both. And if a separate audio recorder or a second camera was running, note it now: it will help you cover the last moments the rebuild can't bring back.

The free first try

Some Sony cameras try to recover an interrupted clip on their own when you put the card back into the same camera with a charged battery. It doesn't happen with every model or every interruption, but it costs nothing. Do it later, calmly, after you have a copy of the card (next step). If a message about recovering data appears, let it finish without switching off, then look for a new .MP4.

Back at the desk: copy the whole card

Before anything else, copy the whole PRIVATE folder from the card to a drive on your computer. The clips are in PRIVATE/M4ROOT/CLIP: the .RSV sits there next to the healthy .MP4 files from the same day. Work only on that copy, never let a tool save its output onto the card, and keep the card untouched until the project is delivered.

Renaming .RSV to .MP4 won't help, and a video converter can't read the file either. The camera writes picture and sound as it records and adds the index at the end, when you press stop. That index was never written, so the file has to be rebuilt, not converted. Background: What is an RSV file? and why converting doesn't work.

Rebuild the take as an MP4

There are free repair methods that rebuild the index using a healthy clip from the same camera, recorded with the same settings, as a pattern. On a wedding day the clip just before the cut is usually a good match. How to pick one, and why these methods sometimes fail: RSV repair without a reference file.

Lazaclip is our Windows 10/11 program for this (we make it, so take this section as coming from the seller). It works offline, so client footage stays on your computer, and it never changes the original file:

  1. Open the PRIVATE folder you copied. The program lists every .RSV it finds and checks whether each one can be read.
  2. Click Preview 10 s to watch the first ten seconds of the take with a watermark. The scan and the preview are free, so you know whether the program reads your file before you pay.
  3. With a license, save the full .MP4 to a folder on your PC, or repair every .RSV in the folder in one go if more than one take was cut off.

We tested A7S III recordings (XAVC S, XAVC S-I and XAVC HS, rebuilt without a reference clip) and the original a7S with a reference clip. The FX3, FX30, A7 IV, A7 V, A7C II and other cameras listed on our homepage use the same XAVC S / XAVC HS recording format, but we haven't tested files from them yet; the free preview is how you find out for your file. Camera guides: FX3, A7 IV, A7S III.

In the edit

The rebuilt file is a normal .MP4: import it like the other clips from that card. Watch it all the way to the end before you build the sequence on it. The last second or so before the cut can't be recovered, because that final group of frames was never completely written. That is where the second camera angle or the separate audio recording earns its keep.

If you tell the couple or the client anything, tell them what you have checked: which part of the moment is there and which second is missing. Don't promise footage you haven't watched yet.

What a rebuild can't bring back:

  • The final second or so before the interruption.
  • Parts of the file that were overwritten because the card was used again.
  • A file that was deleted, or a card that was formatted. That needs data recovery first; the rebuild comes after.

For the next booking

  • Record to both card slots at once on cameras that have two. It protects you from a pulled or failed card, not from a dead battery.
  • Swap batteries between moments, not in the middle of them, and start the ceremony and the speeches on a fresh battery or on external power.
  • Wait for the camera to finish writing before you open the card door.
  • Run a separate audio recorder for the vows and speeches.