Progressive pipeline
Comparison starts with inexpensive checks and reaches the costliest verification only for plausible candidates. A sampled prefilter precedes full-file SHA-256 for exact copies; five frames perform visual screening, twenty-four build the fingerprint, and forty-eight verify the result. Incomplete verification stays pending or fails closed instead of becoming an actionable match.
- Full-file SHA-256 confirms copies with identical bytes.
- 5 frames for initial visual screening.
- 24 frames for the complete temporal fingerprint.
- 48 frames for final visual verification.
How to interpret results
An exact duplicate has cryptographic evidence over file content. “Same video” and “probable match” instead derive from coherent visual fingerprints across the duration and require checking proof frames, path, size, and quality. Confidence helps prioritize review but does not replace the user’s decision or justify automatic removal.
- Exact duplicate: the complete-file SHA-256 matches.
- Same video: strong visual coherence across the complete video.
- Probable match: enough similarity to review, not to remove automatically.
Current technical limits
The pipeline aligns samples at relative positions across the same duration; it does not search for one sequence inside another video. Segments, offsets, edits, speed changes, reverse playback, crops, reframing, and timeline reuse are therefore unreliable. Audio is excluded, and Similiter does not read NLE project graphs, timelines, or dependencies.
- No segment or subsequence search.
- No audio comparison.
- No NLE timeline or project interpretation.
- No normalization for crops, mirrors, reverse playback, or speed.
Updating Similiter
Starting with 1.1, Similiter checks for updates every 24 hours while the app is open. Change automatic checking and downloads in Settings → General, or use Check for Updates in the Similiter menu. Packages are verified before installation, which takes place on quit once active work has finished.
- To upgrade from 1.0.5 to 1.1, download the new DMG and replace the app in Applications: 1.0.5 does not include Sparkle.
- Keep the app in Applications and finish scans and moves before replacing it manually.
- If a check fails, check your connection and the message in Settings → General.
Checking new videos in the background
Enable monitoring in settings and choose included or excluded folders. The service continues with the interface closed; pausing postpones analysis. Confirmed duplicates can trigger macOS notifications when permitted. Clicking opens saved results for review; monitoring never moves files automatically.
- Previously scanned folders are included automatically unless explicitly excluded.
- Results remain available in Added Files Review even without notifications.
- A drive must be mounted and readable; incomplete checks resume when it becomes available.
- Use Disable Monitoring to stop the service. Quitting the interface does not disable it.
Moving duplicates on a NAS or into a collection
Use Move to Folder to collect selected copies while preserving their original path structure. When macOS Trash is unavailable, an existing writable Synology #recycle folder may also be offered. The report shows completed moves, remaining files and receipts for manual recovery.
- Unselected files and original folders remain in place; at least one verified copy must remain per group.
- To reclaim space, delete the collection or empty the NAS Recycle Bin after review.
- Use the receipt’s original paths to recover a collection; integration with DSM’s Restore action is not guaranteed.
- After a partial failure, review the report and retry only the files that remain selected.
Performance and benchmarks
No reproducible large-library benchmark is published, so this documentation makes no time claim for thousands of files or terabytes. A credible benchmark must state version, hardware, corpus, codecs, file count, hours and TB, first scan, cached scan, errors, false positives, and verification criteria. Until then, “built for large libraries” remains intentionally absent.
- Repeat scans can reuse metadata, hashes, and fingerprints for unchanged files.
- Speed depends on codecs, duration, storage, and decoding.
- Performance figures will be published only with a reproducible corpus and method.