Lazaclip

A7 IV RSV file: recovering an interrupted recording

Updated 7 November 2026

The A7 IV is the camera many people use for both photos and video, at weddings, events and on trips. When a battery dies or a card comes out during a video, the camera leaves a file ending in .RSV instead of an .MP4. The clip is missing from playback and your editor won't import it. This guide explains what that file is and how to turn it back into a video you can use.

Why there is an .RSV instead of an MP4

While you record, the camera writes video and sound into a working file with the .RSV extension. At the end of a normal recording it writes the index (where every frame and every piece of audio is in the file) and renames the file to .MP4. If the power is gone before that moment, there is no index and no rename. Your recording is in the file; players just can't read it yet. More background: What is an RSV file?

The A7 IV records XAVC S and XAVC HS (and, depending on settings, XAVC S-I) into .MP4 files, so an interrupted recording in any of these formats becomes an .RSV.

First, keep the card safe

  • Don't format the card. Not in the camera, not on a computer.
  • Don't record the rest of the day on it. Use another card from now on.
  • Don't delete the .RSV, even though it looks broken.
  • Copy the card. In a card reader, copy the whole PRIVATE folder to your computer. The videos are in PRIVATE/M4ROOT/CLIP; your photos are in DCIM and are not affected.

Look at both card slots

The A7 IV has two slots: slot 1 for a CFexpress Type A or SD card, slot 2 for an SD card. Many A7 IV users record video to both cards at once, or use one slot for photos and the other for video. If both cards were recording and only one was pulled, the other one may hold a finished .MP4 of the same clip. After a dead battery, both cards normally hold an .RSV; copy both before anything else.

The free try: put the card back in the camera

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 every time, and we can't say in advance whether your A7 IV will do it for your clip, but it costs nothing. With the card copied, charge the battery, put the card back into the same A7 IV and slot, and switch on. If a message about recovering data appears, let it run to the end and don't switch off. Then check the CLIP folder for a new .MP4.

Rebuild the recording as an MP4 on Windows

If the .RSV is still there, it needs a new index. Lazaclip is our Windows 10/11 program for exactly this (we make it, so this is our own product we are describing). It works offline and doesn't upload your footage:

  1. Open the card or the folder you copied. Each .RSV is listed with a note on whether it can be rebuilt.
  2. Click Preview 10 s. The first ten seconds of your clip open in your video player with a watermark. Scanning and the preview are free.
  3. With a license, save the full clip as an .MP4 on your PC, one file at a time or all of them at once.

The picture and sound are not re-encoded: the program keeps the recorded data exactly as the camera wrote it and only adds the missing index. The original .RSV is left as it is.

Has it been tested with the A7 IV?

No, not yet. Our tests so far are on A7S III recordings (XAVC S, XAVC S-I and XAVC HS, rebuilt without a reference clip, with frames and audio identical to the original up to the last unfinished group of frames) and on the original a7S. The A7 IV uses the same XAVC S / XAVC HS recording format; the free preview shows whether the program can read your file before you pay.

What you get back

  • The clip up to the last second or so before the cut. That last moment was never completely written and can't be rebuilt.
  • The sound as recorded, from the camera microphone or the mic you plugged in.
  • An .MP4 about the size of the .RSV; save it to a drive with enough free space.
  • S-Cinetone and S-Log3 clips look the way they always do from this camera; XAVC HS needs an editor with H.265 support.

Avoiding it next time

  • Hybrid days drain batteries fast. Swap the battery during a break, not in the middle of the speeches or the first dance.
  • Recording video to both slots at once means a second copy of every clip.
  • Wait until the camera has stopped writing before switching off or opening the card door.
  • Carry a spare card, so a card with an .RSV can stay untouched until you are home.

Upgraded to the newer body? See the A7 V guide. Low-light work on an A7S III: the A7S III guide.