EdgeVis provides recording integrity checks that can support an organisation’s evidence handling process. This article covers EdgeVis Mobile Encoder, EVVR hardware encoders and EVVR Container, where the relevant recording and watermark capabilities are enabled.
What does watermark validation check?
Fragile watermarking helps identify changes to recorded data. Frame hashes are stored with the native recording and compared with recalculated values during verification. A mismatch is a reason to investigate possible alteration or corruption.
A successful result applies to the checks performed on the files examined. It does not, by itself, establish that every recording file was supplied, that the timeline is complete, that the camera clock was accurate or that the scene was authentic.
Preserve the native recording
Keep original CSX/CSXS files and their associated recording structure. Retain available database and archive folders rather than only selected video files. An exported MP4 is useful for viewing, but should not replace the native recording when later verification may be required.
Suggested verification and export workflow
Identify the source. Record the product type, device or host reference, camera/channel, recording period and relevant software versions.
Preserve the original. Retain the native files and associated folders under your organisation’s handling procedures.
Check the footage. Review the timeline for availability, camera selection, time-zone interpretation and any gaps.
Validate available watermarks. Record the tool/version, scope and results. Investigate failed checks; distinguish unavailable watermarking from a successful validation.
Export the required range. Media Manager can extract encoded streams without re-encoding. Document the selected range and any further processing.
Retain the supporting record. Keep export metadata, verification results and a record of access, copies, transfers and recipients.
What information accompanies an export?
The command-line exporter produces XML metadata containing UTC recording times, duration, channel/codec information and watermark status/results. Keep the XML with its corresponding MP4 and native source reference.
Encryption and integrity are different controls
CSXS password encryption controls access to recordings. Watermark validation checks recorded data for changes. An encrypted file is not automatically a verified file, and successful playback is not a substitute for reviewing verification results.
Does verification guarantee admissibility?
Integrity checks are one part of an evidence handling process. They do not determine legal admissibility. Follow the procedures applicable to your organisation and jurisdiction, including retention, disclosure and chain-of-custody requirements.