This case arrived in the client’s own words, and they’re worth quoting directly:
“My SD cards somehow just completely wiped to nothing after shooting all day, but I recovered successfully all of the video files I needed except for 1 file, it is a 19.16 GB mp4 that I can’t seem to repair like the others did.”
A full day of shooting, two cards wiped for reasons unknown, and a client who had done everything right: he’d recovered nearly everything himself, and every recovered file repaired cleanly — except one. A 19.16 GB MP4 that resisted repair the way its siblings hadn’t. When one file in a batch behaves differently from all the others, that difference is the diagnosis — and this one pointed somewhere specific.
The problem — why one file refuses what worked for the rest
When “the others repaired fine but this one won’t”, the usual explanation is that this file’s fragments are laid out differently — bigger file, more fragments, and crucially: a fragment pattern the repair tool’s assumptions don’t fit. A 19 GB recording is fragmented on a scale small clips never reach.
And in this case there was a second factor, one we confirmed during analysis: the Sony camera had proxy recording enabled. Proxy mode writes two versions of the footage simultaneously — the full-resolution master and a lightweight low-resolution proxy for quick editing — interleaving high- and low-resolution fragments across the card. For the small files, the client’s tools coped. For the biggest one, the dual-stream fragment pattern overwhelmed them: fragments of two different video streams, mixed together, with the largest file holding the most of both.
Repairing the recovered file was therefore a dead end before it started — the file’s assembly was wrong at the storage level. The real data was still on the card. The answer was to go back to the source.
What we did — card imaging, then dual-stream fragment reassembly
Our reply set the client a clear path, and he followed it precisely:
- Step 1 — Image the card. Following our instructions, the client created a complete image of the SD card on his own computer, preserving every byte exactly as it was, and shared it with us. No shipping, no card leaving his hands.
- Step 2 — Low-level reassembly on the image. We analyzed the dual-resolution fragment pattern: separating master fragments from proxy fragments, mapping each stream’s true order, and reconstructing the 19 GB master recording fragment by fragment in its correct sequence.
- Step 3 — Verify and deliver. The reassembled MP4 was played through completely and checked against the day’s other footage before delivery.
✓ Result
The 19.16 GB MP4 was recovered completely — delivered within 2 days of receiving the image. With it, the client’s day was whole again: every file he’d recovered himself, plus the one that had refused to come back, playing clean at full quality.
Proxy recording: a hidden multiplier of recovery difficulty
Worth knowing if you shoot Sony (or any brand) with proxy mode on: that convenient second stream is written to the same card, interleaved with your master footage. Day to day you never notice — the camera manages both streams invisibly. But after a wipe or format, recovery has to untangle two interleaved fragment streams per recording, and generic tools simply aren’t built for that. If you’ve had one file resist recovery while its siblings came back, check whether proxy recording was enabled — it’s often the reason.
This doesn’t mean you should stop using proxies — they’re genuinely useful. It means that if the worst happens, expect the recovery to need dual-stream fragment handling, and say so when you contact a service. It changes the approach from the first minute.
Takeaways
- Cards “wiped to nothing” after a full day are usually recoverable — stop using them immediately.
- One stubborn file among many recovered = that file’s fragment layout is different; don’t keep re-repairing it, go back to the card.
- Proxy recording interleaves two resolutions of fragments — a hidden difficulty multiplier for the largest files.
- Card imaging + cloud sharing keeps recovery fully remote: your card never leaves home.
- Tell your recovery service up front if proxy mode was on — it shapes the entire approach. We provide professional Fragment Data Recovery Service.