How we verify that a file is really recovered

01 / Signature

Step one: is this even that file type?

Every media format begins with a recognisable structure. JPEG starts with a fixed byte sequence, MP4 and MOV begin with a box structure, WAV with a RIFF header. The first step therefore checks whether the beginning of a candidate actually matches the format its extension claims.

That step alone is never sufficient. A correct beginning says nothing about whether the rest of the file is present and contiguous. This is exactly where many tools stop and report success anyway.

02 / Structure

Step two: is the file consistent with itself?

The second step reads the internal structure. For container formats that means: do the declared sizes of the individual sections match the actual file size? Do index structures point at ranges that really exist? Does the file end where its own layout says it should?

For fragmented recordings that is the decisive question. A video file whose management data sits at the end can look entirely unremarkable at the start and still break off in the middle.

03 / Decoding

Step three: can it actually be read?

For video and audio, structural checking is not always enough. Bundled media tools are therefore used to analyse containers and streams and, where needed, to actually demux and decode them. Only when the tracks can be read across the expected duration is a recording dependably confirmed.

This check costs time. It is why a clean run takes longer than a plain hit list, and it is the difference between a number in a results window and a file that genuinely opens in your editing software.

04 / Export

Step four: the export must not break anything

1. 1

   The export first writes to a file ending in .partial, so an interruption never leaves behind an apparently finished file.

2. 2

   Once written completely, the destination file is checked a final time and only then given its final name.

3. 3

   Destination file names are assigned uniquely. An existing file at the destination is never overwritten.

4. 4

   Exporting to the source device is blocked and cannot be bypassed with a setting.

5. 5

   Results that were not fully confirmed keep the .UNVERIFIED marking in their file name.

05 / Repair

Repair leaves the original untouched

When a damaged recording is repaired, the unmodified reconstruction is preserved. You therefore always keep the state the recovery actually found, plus the repair result. That keeps it traceable which part of the result comes from the source and which from a reconstruction.