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Repair a corrupted Sony FX3 video

When an FX3 clip stops opening, it's almost never lost footage — it's an XAVC recording the camera never got to finalize. The frames are still in the file; what's missing is the index that points to them, and it never has to leave your machine to get back.

Your file never leaves your device — repair runs in your browser. 0 bytes uploaded.

Your data is the big block — usually intact. What breaks is the small index. Repair rebuilds it.

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The Sony FX3 (ILME-FX3) is a Cinema Line full-frame body built on the A7S III sensor, recording into standard MP4 files using one of three XAVC flavours: XAVC S (H.264 Long GOP), XAVC HS (H.265/HEVC), and XAVC S-I (All-Intra H.264), at up to 4K 120p with 10-bit 4:2:2. Every one of those is an MP4 that only becomes playable once the camera writes its moov index at the end of the take. If that final write never happens, you get a file full of real XAVC data and no map to it. Drop the clip above and the tool checks for exactly that, in your browser, and rebuilds the container when the footage is recoverable.

How the FX3 writes XAVC — and where it breaks

Whatever menu option you pick, the FX3 wraps its video in an MP4 container; the three formats differ only in the codec inside. XAVC S is H.264 (AVC) Long-GOP, the most broadly compatible option. XAVC HS is H.265/HEVC, which packs more detail into a smaller file but needs an HEVC-capable player. XAVC S-I is All-Intra H.264, where every frame is a full keyframe, at very high bitrates. In every case the picture data is streamed to the card as you shoot, but the moov atom — the table that tells a player where each frame lives and how to decode it — is written only when the clip is finalized, at the moment you press stop or the take ends cleanly.

Here's the FX3's own twist: unlike a compact mirrorless body, the FX3 has an active cooling fan and is rated for effectively unlimited recording, so it almost never thermally shuts down. That takes overheating off the table and leaves power and storage as the real culprits:

  • The battery died mid-take. High-bitrate 4K drains an NP-FZ100 fast; if the pack cuts out during a long clip, the finalization write never runs.
  • The card was pulled, or a door opened, while the access lamp was still writing — the tail of the file, including the index, is simply never committed.
  • A card write error (often shown as C:13:01). Sony's C:13:01 is a memory-card fault that appears during heavy writes; it can truncate the current clip rather than erase it.

CFexpress Type A, SD, and the reference clip

The FX3 takes CFexpress Type A cards and SD UHS-II in its dual slots, and the format you shot dictates what the card must sustain: XAVC S-I and the highest-bitrate 4K/120p modes really want CFexpress Type A, while lighter XAVC S can live on a fast V60/V90 SD. Feed a demanding mode a card that can't keep up and the write can stall or truncate — which is often the story behind an unfinalized last clip.

Rebuilding a missing moov means scanning the surviving stream and reconstructing the sample tables the camera would have written. That job is far more faithful when it has a healthy clip from the same FX3 shot in the same format and settings — same XAVC flavour (S, HS or S-I), same resolution, frame rate and bit depth. That reference carries the exact codec configuration (SPS/PPS for H.264, or VPS/SPS/PPS for HEVC) the broken file is missing. Grab a normal clip from the same card, keep it handy, and if you switched between XAVC S and XAVC HS, make sure the reference matches the codec of the broken clip, not the other one. You'll only be asked for it if the file needs it.

What this can and can't fix

Can fix

  • The last clip when the battery died or you cut power mid-record (unfinalized MP4, missing moov)
  • Clips truncated by a card write error or a C:13:01 fault during recording, where the video data survived
  • XAVC S (H.264), XAVC HS (H.265/HEVC) and XAVC S-I files that copied off the card but won't play
  • Container damage: broken or missing index, wrong sample offsets, bad timestamps

Can't fix

  • Footage physically lost to a failing or worn CFexpress Type A / SD card (recover the card first, then repair)
  • A clip whose reference you can't match — e.g. no healthy XAVC HS sample for a broken HEVC file
  • Files that read as 0 bytes or as mostly zeros after a card failure
  • Sony's encrypted/DRM-protected or otherwise locked exports

If a repair fails, we tell you why (missing data versus broken structure), and you are never charged for a failed repair.

FAQ

The FX3 has a fan and doesn't overheat — so why did my clip break?

Because heat isn't the cause on the FX3, the culprit is almost always power or storage: a dead NP-FZ100 mid-take, a card pulled while writing, or a card write error such as C:13:01. Any of those cuts the recording before the moov index is written, leaving a valid clip with no map.

My FX3 clip was XAVC HS (H.265) — does that change anything?

Only the reference. The rebuild works the same way for HEVC as for H.264, but if a reference clip is needed it must also be XAVC HS from the same camera, because HEVC carries a different codec configuration (VPS/SPS/PPS) than the H.264 used by XAVC S and XAVC S-I.

I saw error C:13:01 while filming. Is my footage lost?

Not necessarily. C:13:01 is a card-write fault that often shows up during heavy recording and can truncate the current clip rather than erase it. If the video data was written before the error, the container can usually be rebuilt. If the card itself is failing, recover its contents first, then repair the clips that come off it.

Do I need Sony Catalyst Browse to fix it?

No. Catalyst Browse is for playback, proxy and gyro/metadata work — it can't rebuild a broken container. This repair runs in any modern browser on Mac, Windows or Linux, with nothing to install, and the file never leaves your device.

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